Institute of Water Journal Issue 3

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Issue 3 Spring 2019


We are pleased to present our third issue of The Institute of Water Journal The Institute of Water Journal is a peer-reviewed, technical journal with the sole aim of providing relevant and valuable learning and knowledge on the themes of science, engineering and the environment being applied in a water context, together with thought leadership, innovation and technical developments in other areas such as regulation, customer service and skills development. The Journal contains papers and case studies from authors working across these fields, including regulators, academics and their students, water company personnel and supply chain organisations, including consultants.

Authors are encouraged to consider carefully how readers may be able to readily apply what they have learned from each paper to their role in the water industry, as provision of excellent continuing professional development (CPD) opportunities is absolutely central to the ethos of the Institute of Water. Every paper has been peer-reviewed by a panel of experts from the Institute of Water, industry regulators and key academic partners. You can read more about the panel on page 60. •

Provides relevant and valuable learning for water industry professionals.

Presents new and innovative thinking or research outputs or a different slant on an existing approach.

Contains information and knowledge that many readers will be able to readily apply to their role as part of their Continuing Professional Development.


The HydroSight - A Low Cost Alternative for Real Time Measurement of Flocs Formed During Water Treatment SEVERN TRENT WATER & MALVERN PANALYTICAL


Coagulation Control using On-line Zeta Potential Measurements: Can it Save Money and Improve Performance? CRANFIELD UNIVERSITY & SEVERN TRENT WATER

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of Filta-Max Digital Transformation 14 Application 33 Xpress for Cryptosporidium of Abstraction Licensing Parvum Detection SCOTTISH WATER

Use and Carbon 17 Energy Emissions Across an English Wastewater Network NEWCASTLE UNIVERSITY


The Compliance and Event Risk Index Explained DRINKING WATER INSPECTORATE (DWI)



off the Tap: 42 Turn Behavioural Messages Increase Water Efficiency During Toothbrushing UNIVERSITY OF EAST ANGLIA, ANGLIAN WATER & GLAXOSMITHKLINE

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The HydroSight (Malvern Panalytical) - A Low Cost Alternative for Real Time Measurement of Flocs Formed During Water Treatment G.M.Brown





Severn Trent Water

Severn Trent Water

Malvern Panalytical

Malvern Panalytical

Malvern Panalytical

Abstract The structural characteristics of flocs can play a significant role in their removal during the clarification process. Extreme weather events, such as intense periods of heavy rainfall, can lead to operational difficulties for water utilities, such as the formation of fragile flocs and increased particulate carryover onto downstream processes. Therefore, the ability to assess and optimise floc characteristics during full-scale water treatment is key to effective treatment. At many water treatment works, the only monitoring of floc characteristics upfront of the clarification process is the extremely subjective floc test. The new innovation, the HydroSight (Malvern Panalytical) has shown potential for floc size monitoring

using an online imaging technique. Trials have been carried out to validate the instrument against the Mastersizer (Malvern Panalytical), a larger and more expensive instrument that uses a laser diffraction technique. Initial onsite trials of the HydroSight have been carried out on a water treatment works within Severn Trent, with the instrument being easily accessible to water utilities due to its small size. Subsequent on-site trials have demonstrated that the instrument could provide the means to monitor and trend floc size real time as part of the works SCADA system – which would be a first for the water industry! Keywords: Coagulation; Flocs; Laser Diffraction; Zeta Potential; DV50; Clarification

Introduction Raw water quality is affected by extreme weather events and can vary greatly throughout the year (Parsons et al., 2005). This creates challenges for water treatment works as varying water quality can make the water more challenging to treat. Monitoring floc characteristics is a particularly important means of ensuring the clarification process is optimised, sometimes this is the only means of testing before assessing the clarified water quality. There are currently a number of methods for optimising coagulation, these include laser diffraction, particle counters, zeta potential, and visual analysis. This paper details the current methods for optimising

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based on assessment of floc size, as well as introducing a new piece of technology, the HydroSight (Malvern Panalytical), for the water industry and the trials that have been taking place to validate its results. The first trials of this new innovation were carried out on water from Draycote Water Treatment Works (WTW), a lowland

water source located in the Severn Trent catchment. Previous investigations of ferric floc size measurements have been used for comparison, the research has shown that is that DV50 floc size ranges from 670 950µm (Table 1.) with the flocs achieving optimum size between 7 and 15 minutes of the slow mixing phase.

Table 1. Floc Size Results Obtained During Previous Studies Method

Water Type

DV50, µm


laser diffraction


670 - 790

Jarvis et al., 2012

laser diffraction


785 - 823

Cairns et al., 2008

laser diffraction


906 - 934

Sharp et al., 2006

laser diffraction


850 - 950

Jarvis et al., 2004

Current Methods for Coagulation Monitoring

F igure 1. Floc Comparator

Floc Tests: On most WTW, floc tests are undertaken daily and involve taking a sample after coagulant is added. This is then mixed to imitate the flocculation process. Once this has occurred there will be a visual inspection of the flocs that have been formed to determine a floc size from A-G (Figure.1) to base process decisions. The method relies on familiarity to notice changes from previous results. Therefore, this is an extremely subjective method, which does not generate consistently accurate results and it does not allow continuous monitoring or trending of data. Zeta Potential – The Zetasizer (Malvern Panalytical): The optimisation of coagulation conditions at a number of Severn Trent sites is based on zeta potential measurements. This is monitored both online and in the laboratory using the Zetasizer (Malvern Panalytical ISO13099-2). The process works by monitoring the electrical potential difference between the negatively charged particles and the water. Addition of coagulant, under certain conditions, can neutralise these charges. Post coagulant dose, the zeta potential is measured to indicate under or overdosing, with the optimal range between -10 and +3 mV (Sharp et al., 2005). However, this type of monitoring is only suitable for sites where charge neutralisation is the dominant coagulation mechanism. As Draycote WTW is a lowland water source, it is buffered and will not easily alter pH. The dominant coagulation mechanism is sweep flocculation, therefore heavily relies on ensuring optimal floc characteristics. Floc size – The Mastersizer (Malvern Panalytical): The Mastersizer has previously been proven to give an accurate measurement of the size of flocs formed during water treatment (Sharp et al., 2006),. The Mastersizer operates by using laser diffraction of a particle under red and blue light. The

particle will scatter the light by a certain amount depending on its size and refractive index. Using Mie theory (Martin et al., 1993) the Mastersizer has an algorithm to calculate a spherical particle size from the scattered light (ISO13320). It is a volume based technique. The instrument generates smooth data as it samples a large number of particles at a time through a deep cell. Using the algorithm the DV10, 50 and 90 are shown on a graph at time intervals that can be set by the user (the DV10, 50 and 90 are the values at which 10%, 50% and 90% of the sample has a size of less than the value respectively). For the laser diffraction measurements using the Mastersizer, a sample is passed through a cell inside the instrument with lasers incident on the cell (Figure 2.). The size class readings are then trended on a graph and can allow

comparison of results (Figure 4.). However, the instrument has a high initial cost and is not easily transportable due to its large size. Figure 2. Mastersizer Cell

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The new Innovation – The HydroSight (Malvern Panalytical) The HydroSight is an image-based technique (Juntunen et al., 2014), which takes continuous images of the sample as it passes through the device (Figure 4.). Using an algorithm, it is able to pick out individual particles from the 2D images, and determine their size. As with the Mastersizer, the DV50 can be calculated, which can then continuously calculate the particle size distribution. Captures of the instrument readings can be taken at certain intervals to view the DV50 at a particular point in time, and to save the images of the flocs. The HydroSight also calculates the distribution between the particles within flocs, the greater the size the more distributed they become due to their formation. Data can be collated from a number of captures in the form of a graph to allow comparisons (Figure 5.). The HydroSight is a more portable instrument than the Mastersizer and it is more cost effective.


Floc Diagnostics: The following set up was used for the experiments to compare the floc size calculated on the HydroSight and the Mastersizer (Figure 6 & 7.).

Figure 3. Mastersizer Data View

Figure 7. Equipment Setup

The sample of the flocculated water was pumped using a peristaltic pump set at 30 rpm into the HydroSight and then into the Mastersizer and back into the jar in a continuous loop. Initial testing was carried out to determine the appropriate stir speed and pump speed required for the experiment, it was proven that flocs are very fragile and will break with a slight increase in stirrer or pump speed, as floc size increases they become increasingly unstable (Jarvis et al,. 2005). 30 rpm pump speed was determined to be the optimum for floc stability and sample flow. After flash mixing in the jar test, samples were taken at one minute intervals from 0 to 15 minutes throughout the slow mixing process. Floc size diagnostics were carried out as the flocs were growing and the DV50 recorded from each instruments.

Figure 5. HydroSight Data View

Figure 4. Inside View of the HydroSight

Testing of the HydroSight Methods: Raw water from Draycote Water Treatment Works was used for experiments both in the laboratory at Malvern Panalytical and onsite (Table 2).

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Figure 6. Equipment Schematic

Table 2. Draycote Raw Water Parameters Parameter


Total Hardness as CaCO3 293 mg/l Turbidity

1.0 - 5.0 NTU


7.5 (Summer) 8.3 (Winter)

UV absorbance

11 - 14 ABS/ Metre

Dosed pH (Ferric Sulphate)

7.2 – 7.3

Laboratory Testing: Coagulation Jar Test: At room temperature, 20oC, a 1 litre sample of the raw water from Draycote WTW was dosed with 35µl, 7mg/l, of Ferric Sulphate. This dosed water was then flash mixed using a benchtop magnetic stirrer at 200 revolutions per minute, rpm, for one minute and slow mixed at 30 rpm for 15 minutes.

On Site Testing: Floc size measurements were taken at three sample points onsite at Draycote WTW (Figure 8.). The raw water at Draycote WTW is abstracted from a non-impounding reservoir, the water passes through screens and strainers before it is pumped to the works and dosed with 5.0 mg/l of Ferric Sulphate in a static mixer. Dosed water then enters nine sets of flocculators. There are two stages of flocculators at Draycote WTW with the first turning at 1 ¼ rpm and the second at 1 rpm. Once the flocs are formed the water then enters the floc outlet/DAF inlet channel.

Figure 8. Schematic for Onsite Testing at Draycote WTW

The sample of the flocculated water was taken from the floc outlet/DAF inlet channel and it was pumped using a peristaltic pump set at 30 rpm into the HydroSight with the tested water going on to waste. The HydroSight was run for 1 hour in each location and the DV50 measurement recorded after the hour period. The testing was carried out twice on two of the DAF streams. The points included: • Floc outlet/ DAF inlet on two of the streams (sample point 3) • In the first flocculator on two of the streams (sample point 1) In the second flocculator on two of the streams (sample point 2)

Results and Discussions: The camera system used by the HydroSight is able to continuously capture images of the sample and equate these to a size (Figures 9-12). The images below show that there is a visible increase in size throughout the flocculation period, something that is not so visible to the naked eye. The HydroSight will provide a greater insight into the formation of flocs as it has shown that some flocs are smaller than others, and they are not perfectly uniform shapes (Jarvis et al,. 2005), which could allow better optimisation of the coagulation process. The sizes tend to vary over the 15 minutes with some flocs still being small

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after the time period. Figures 9-12. Images Captured Using the HydroSight of Increasing Floc Size During Jar Testing 1 min

5 mins

10 mins

15 mins

When using the HydroSight to analyse the floc size at the three different sample points detailed in figure 8, there was both a visible increase and an increase in DV50 from sample points 1 – 3. This observation was expected due to the flocs forming and increasing in size throughout the flocculation

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stages. The images also correspond to those observed during the jar testing over a similar time period (Figures 13-15.). Figures 13 – 15. Images of Flocs at the Three Sample Points in Stream 4 Point 1

Point 2

Point 3

DV50 results were collected during the laboratory jar testing and onsite during the flocculation process at Draycote WTW, this has allowed comparison between the two instruments during the jar testing and to assess the reliability of the HydroSight readings onsite (Figure 16.). From the results below it is proven that the HydroSight is able to calculate very similar readings to that of the Mastersizer – a previously validated instrument. Not only do the results throughout the laboratory jar test show a similar trend on both instruments, the onsite test results plotted at approximately the same time period since coagulant addition are also in line with the results from the jar


testing. There is however some variation in DV50 due to the non-uniform nature of flocs. DV50 values appear to drift after 12 minutes, this could be due to the varying sizes in the sample, some are very large, however some remain small. The results validate the HydroSight against the Mastersizer and show that the instrument has the potential to provide reliable onsite data. To further validate the HydroSight readings observed at Draycote WTW, a comparison between Figure 16. and the results in Table 1. show that similar ferric floc size results have been obtained in the testing discussed throughout this paper and from previous testing of the Mastersizer. With a range of Fe floc sizes of 670 – 950µm from Table 1. the results in Figure 16. are in line with this range. There is also the same trend of flocs reaching their optimum size between 7 and 15 minutes of slow mixing. Following the laboratory trials it was shown that the HydroSight has the potential to give valuable data to the water treatment works on the characteristics of flocs formed during the flocculation process. Draycote WTW was chosen to be the trial site due to currently having little coagulation monitoring. After two days of initial trials it has been determined that a longer trial under different weather conditions and seasons would allow further analysis of floc characteristics, with an optimum range for floc size being obtained. There is a large distribution of flocs of varying size observed during the flocculation period (Figure 17.), by carrying out a longer trial a more detailed picture of the average floc size for the works would be obtained. From comparison of the images captured on the HydroSight, it has shown that there are still some smaller flocs after the flocculation period and that there will always be a range in sizes observed (Figure 18.). In conclusion, the results from the onsite testing have shown that the HydroSight could provide valuable data to the site team. The HydroSight is also able to monitor and record changes that would be expected throughout the process, and

Figure 16. DV50 Size Results During the Flocculation Period

Figure 17. Size Distribution from Floc Outlet Channel

therefore could be used as a diagnostics tool for process efficiency and comparisons between the different flocculation streams. Greater sensitivity to the changes in floc size during the process could also be achieved if future versions of the HydroSight software enabled automated measurement capture over specified time windows. This way, each size distribution would only describe the size of the flocs passing through the instrument during that narrow time frame (rather than accumulated size distributions over the course of the entire measurement).

Further trials are planned at Draycote WTW to monitor flow characteristics over both a longer period of time and across different seasons, the data can then be trended with water quality data pre and post clarification to compare the effects of floc size on clarified water quality. This will allow determination of the optimum floc size range for Draycote WTW. Acknowledgements The author would like to acknowledge the support of Malvern Panalytical and Severn Trent Water.

Figure 18. HydroSight Image of a Floc

References S.A.Parsons, B.Jefferson, P.Jarvis, E.Sharp, D.Dixon, B.Bolto, P.Scales, Treatment of elevated organic content waters, AWWARF, Denver, CO, 2005. P.Jarvis, E.Sharp, M.Pidou, R Molinder, S.A.Parsons, B.Jefferson, Comparison of coagulation performance and floc properties using a novel zirconium coagulant against traditional ferric and alum coagulants, 2012. R.Cairns, K.Maher, B.Jefferson and E.Sharp, The impact of water sources on the characteristics of natural organic matter flocs formed during drinking water treatment, 2008. E.Sharp, Mastersizer trial, 2006. P.Jarvis, B.Jefferson, S.Parsons, The duplicity of floc strength, 2004. E.L.Sharp, S.A.Parsons, B.Jefferson, Coagulation of NOM: linking character to treatment in: Proceedings of the IWA Particle Separation Conference, Seoul, Korea, 1-3 June, 2005. E.L.Sharp, P.Jarvis, S.A.Parsons, B.Jefferson, Impact of fractional character on the coagulation of NOM, Environmental science and Technology, 2006. R.J.Martin, Mie Scattering Formulae for Non-spherical Particles, 1993 P.Juntunen, M.Liukkonen, M.Lehtola, Y.Hiltunen, Characterization of alum floc in water treatment by image analysis and modelling, 2014. P. Jarvis, B. Jefferson, J. Gregory, S.A. Parsons, A review of floc strength and breakage, 2005. P.Jarvis, B.Jefferson, S.A.Jefferson, Measuring Floc Structural Characteristics, 2005.

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Coagulation control using on-line zeta potential measurements: Can it save money and improve performance? Ryan Smith

Francis Hassard

Emma Sharp

Peter Jarvis

Severn Trent Water

Cranfield University

Severn Trent Water

Cranfield University

Lorena Montalban

Thomas Worley

Peiying Liu

Bruce Jefferson

Severn Trent Water

Severn Trent Water

Cranfield University

Cranfield University

Abstract The application of zeta potential monitoring for coagulation control during drinking water treatment is a relatively new concept that has been shown to deliver increased treatment resilience and reduced coagulant demand compared to traditional approaches such as jar testing and turbidity or UV monitoring of raw water. This has been previously demonstrated through the use of daily spot samples or on-line data used to inform operator decision making. The current study extends this to its ultimate conclusion of automatic

coagulation control through the use of on-line zeta potential monitoring. Analysis of the trial demonstrates the successful use of the automatic control system with a corresponding reduction in coagulation demand beyond that seen previously with just online monitoring. The overall impact of switching to zeta potential based coagulation control is a 20-30% saving in coagulant whilst maintaining clarified water quality. Keywords: zeta potential, coagulation control

Introduction Coagulation is a core unit operation in drinking water treatment for effective removal of natural organic matter (NOM) and particles from surface water sources. Efficient and resilient operation requires an appropriate coagulant dose to be applied at all times to match variation in the incoming water properties. Commonly, the dose requirements are established through empirical bench scale jar tests or linked to on-line measurement of some surrogate parameters such as turbidity or light absorbance at a range of wavelengths with the most common being 254 nm. These surrogate measures provide feedforward estimates of dose requirements. However, none of the commonly measured parameters

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properly reflect the mechanisms of NOM removal which are known to be based on charge interactions (Jefferson et al, 2004). The actual required dose is based on adding sufficient charged coagulant molecules to balance, or more correctly nearly balance, the charge exerted by the water. The latter is defined by the combination of the dissolved organic carbon concentration and the charge density of the molecules. The former relates to the dose and the pH of application as the charge neutralising power of the coagulant decreases as the pH goes up. This is manifested in optimised coagulation conditions being under acidic conditions such as pH 4.5 for Ferric, referred to in some parts of the world as enhanced

coagulation. In waters containing a high level of alkalinity it becomes prohibitive to reduce the pH during coagulation due to costs and as such the system is run under higher pH conditions where the charge delivered by a unit mass of coagulant is very low. Consequently, the dose required to balance the charge exceeds the precipitation threshold for the metal salt and the coagulant precipitates, switching mechanism to what is commonly referred to as Sweep flocculation. Accordingly, it is posited that monitoring and control of coagulation through charge measurement will enhance performance and resilience when treating waters containing a low to medium alkalinity level.

The authors have been exploring the use of zeta potential to control coagulation performance since the early 2000s demonstrating that coagulation is optimised when the post coagulation zeta potential lies within a window of -10 mV to +3 mV (Jefferson et al, 2004). Operation below the negative limit means that insufficient coagulant is being added (or the pH is too high) such that easy to coagulate organics will pass through the process and the subsequent disinfection by-product (DBP) levels are expected to increase or that disinfection efficacy may be inhibited. Operation towards the more positive end simply means that the coagulant dose is higher than required and that savings can be made. Extending the value beyond the upper limit again reduces performance and increases DBP formation. As such, the best situation for effective use of chemicals is to operate as close to the edge of the negative end of the window as possible. However, it is unclear whether operation towards the edge of the window negatively impacts on the consistency of the clarified water quality. This concept was applied industrially in 2007 by initially conducting an 18 months survey of all Severn Trent surface water sites (Sharp et al, 2007). In 2008 a bench top unit was installed on one site and the regular monitoring (daily) of zeta potential used to inform operations (Sharp et al, 2008). The outcome was to lower coagulant dose, operating nearer the negative edge of the zeta potential window. Assessment of the saving saw a 22% reduction in coagulant and a 10% reduction in sludge production. In addition, the performance of the site improved with a more robust performance in terms of residual turbidity and an easy guide for rapid assessment of coagulation performance. The following year a similar set up was commissioned at another site where further development work was undertaken. Ultimately this led to the use of an on-line version of the system which was installed in 2014 (Sharp et al, 2016) with additional online systems at three other sites going in shortly after. In all cases the instrument was used to monitor rather than control

Figure 1: Profile of flowrate, raw water UV absorbance, coagulant dose and the zeta potential during the automatic coagulation trial period.

whilst confidence in its use was established. The initial trials showed good correlation with the bench top unit such that in the summer of 2018 one of the units was used directly for automatic coagulation control for an initial period of three weeks. It was believed that this would enable resilient operation of the coagulation process closer to the negative edge of the zeta potential window without impacting performance and hence delivering further saving in coagulant demand. To the authors knowledge this is the first reported use of using on-line zeta potential for automatic coagulation control. The current paper reports on the trials and lessons learnt from the other sites to discuss a way forward when using the instrument.

top unit. The control algorithm assessed the rolling zeta potential average for the preceding hour and compared to the set point. A maximum change in coagulant dose was set limiting the maximum change in any 24 hour period to + 1.0 mg/L and – 0.5 mg/L. The loop cycle varied between 3 and 4 hours and the set point was altered between -8 mV and -10 mV during the trial period. In addition, samples of the raw water were taken during the trial for charge density measurement. The measurement involved determining the amount of a fixed charge polymer (polyDADMAC) required to neutralise the charge of a sample of the water in a stirred beaker (pH fixed to 7), measured as a zero zeta potential on a bench top unit.

Materials and methods

Results and Discussion

All the sites with on line zeta potential monitoring (Zeta sizer WT, Malvern Panalytical) were typical surface water treatment works based on a flowsheet containing coagulation, dissolved air flotation and depth filtration. Samples were pumped from the flocculators to the zeta sizer through a loop with relative fast flow from which a sub sample was drawn off to the measuring unit. Samples were analysed based on the standard electrophoretic mobility measurement used in the bench

The function of the on-line zeta potential monitor was switched from monitoring to automatic coagulation control between 2nd and 20th July 2018. During the trial, the flow decreased from a starting rate of around 32 ML/d down to around 16 ML/d at the end. Concurrently, a reduction in flowrate was also observed during the night period each day and this was attributed to algae in the intake. Characterisation of the raw water revealed a gradually declining UV absorbance across the trial from 14.4

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Comparison to the earlier 18 months sampling campaign indicates that the raw water has a reduced organic level and increased turbidity levels relative to the previous samples. To illustrate, average levels across the sampling campaign were 25.1±2.2 abs/m for UV absorbance and 3.4±0.8 NTU for turbidity. Additional measurement during that period reported a dissolved organic carbon (DOC) concentration of 6.7±0.7 mg/L with 20-31% of the measured organics being characterised as uncharged hydrophilic organics. The importance of this fraction is that it is known to be recalcitrant to removal by coagulation and hence indicates a probable minimum residual organics level, equating to between 1.5 and 2 mg/L of DOC (Sharp et al, 2007). Laboratory analysis of sampling during the trial confirmed this with optimised DOC residual of 1.5 mg/L during standard jar test trials. In addition, daily laboratory monitoring of the raw water indicated a DOC level slightly lower than previously reported at 5.8±0.1 mg/L. This corresponds to a specific ultraviolet absorbance (SUVA) range between 1.9 and 3.4 during the current trial compared to an average of 3.7 during the previous sampling campaign. The levels are in the medium range indicating a water that is not dominated by hydrophobic material and most likely reflects the influence of algal organic matter (AOM) of the total source water character. The charge density of the raw water varied between 4.6 and 7.7 meq/g with an average of 6.1±0.8 meq/g equating to a total charge load of 35.7±4.4 meq/L. The profiles observed during the trial offered more variability then commonly observed as indicated by comparison to the subsequent 10 days of operation when the plant switched back to operator control utilising zeta potential monitoring. During this period the flowrate (16.1±0.5 ML/d), raw water UV (19.1±0.39) were more stable and the raw water turbidity rose slightly to 5.8±0.8 NTU.

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Figure 2: Example of control system in operation. Set point is -9mV and the loop time is 4 hours.

Analysis of the automatic control system in operation revealed stable performance and effective management of the residual zeta potential around the chosen set point level. Illustration of the control is shown across a two-day period, for a set point of -9 mV, where the coagulant dose varied between 9.2 and 9.9 mg/L (Figure 2). The response of the system is highlighted at two points: Point A, equating to a time of 15:13 on the 7th July, the rolling average of the zeta potential over the last hour was -8.56 mV and as a consequence the coagulant dose was decreased from 9.55 mg/L to 9.47 mg/L. Then at point B, equating to a time of 7:23 on the 8th July where the coagulant dose was increased from 9.44 to 9.64 mg/L as the rolling average zeta potential was too negative at -9.42 mV. Analysis of the performance data demonstrates that the auto coagulation control is an effective way to manage coagulant dose. Operation to a set point of – 10 mV enabled a coagulant saving of 6% without negatively impacting on the overall performance (Table 1). The importance of this is that the automatic coagulation control system provided the confidence to operate at a lower set point and further drive down coagulant costs. Interestingly, the raw water UV signal increased by 73 % towards the end of the trial period indicating that with alternative feedforward systems, an increase in coagulant dose would have been expected. This reflects that UV is a poor surrogate of coagulant

dose demand and much greater control can be achieved through measurement of zeta potential as it has a direct link to the mechanistic action of the coagulant. To place the current findings within a broader context it is worth reflecting the finding when either bench or on-line zeta potential monitoring was used to support operator decisions (Sharp et al, 2016). During those trials, the average coagulant dose was 12 mg/L and varied between 9.5 and 15.2 mg/L indicating more demanding water qualities were being treated. In this case, a 20% saving in coagulant was observed by switching to the use of zeta potential monitoring in general. The 4% saving reported here when switching from manual use of zeta potential readings to an automatic control system and as such can be considered additive leading to a potential overall saving of upto 30% for sites adopting zeta potential coagulation control (Table 1). This will deliver additional savings in sludge production and increased resilience of operation indicating the breadth of benefits delivered by use of zeta potential. Experience from the different sites utilising on-line zeta potential measurement has identified the best sampling location is from the flocculation tank. This provides the most robust measurements and sufficiently short lag times to enable maximum effectiveness of the control loop. Validation of the setup was accomplished

through comparison to a co-located bench top unit with an internal threshold of 2 mV between measurement devices. Throughout the trials a consistent bias has been observed with the on-line analyser reading a lower magnitude value than the bench unit of between 0.5 and 2.0 mV and hence within the identified threshold limits (Sharp et al, 2007). Comparison across the trials has also identified effective maintenance requirements related to monthly cleaning of the header tank along with replacement of the pipes and the zeta cell. This is more frequent than the bi monthly change in the zeta cell typically used with the bench top unit and reflects the greater use it is involved in. Assessment of the operator’s experience identifies two re-occurring issues that need to be considered when thinking about the maintenance schedule: the contamination of the zeta cell and bubbles in the line. In terms of the former, a new cell was compared to a series of used cells in a bench top unit measuring a calibration solution (-42±4.2 mV). The resultant values were -42.1±0.9 mV for the new cell and between -34.8±0.6 mV and -39.8±0.68 mV when testing a series of used cells after they had each had 1 month of use involving 600 reading per day. Consequently, the increased use with the on-line system does not appear to cause additional contamination issues compared with (or to) standard laboratory use. The other issue manifests through a decrease in the magnitude of the zeta potential over short time periods without changes in dose. Inspection of the system revealed the accumulation of bubbles within the pipe line resulting in up to a 3 mV reduction in the magnitude of the reported zeta potential. However, removal of the bubbles, through massaging the pipe, resulted in the on-line data restoring to expected levels within 15 minutes. The ultimate impact of maintenance is observed through comparing standard (monthly) with intensive (daily) maintenance frequencies (Figure 3). The impact is a reduction in the range of the zeta potential value observed from -10.3 to -7.7 mV on the standard schedule to -9.7 to -8 mV on the intensive schedule. Whilst

Table 1: Comparison of average values with and without automatic control with zeta potential


Auto coagulation control

Zeta potential (mV)

Manual coagulation control (post trial)

Set point -9 mV

Set point -10 mV

Set point -9 mV




Dose (mg/L)




Clarified turbidity (NTU)




Filtered turbidity (NTU)




Figure 3: Comparison of the variation in the zeta signal with daily maintenance (open circles) and less frequent maintenance (filled circles) 100% 90% 80% 70% Percentile (%)

to 11.1 abs/m for the first 16 days which then rose to between 19.3 and 19.9 abs/m thereafter (Figure 1). The corresponding turbidity varied between 2.2 and 8.3 NTU and the pH between 6.1 and 7.1.


60% 50% 40% 30% 20% 10% 0% -12



-9 Zeta potential (mV)

this provides evidence of the narrowing of the ranges it remains unclear whether this would impact the efficacy of the control system.

Conclusions The use of on-line zeta potential measurement as a means of automatic feedback control for coagulation dosing has been demonstrated. This extends the successful use of off-line and on-line zeta potential monitoring for use by operators to control coagulant dose. The system enables confidence in operating at more negative set points, truly optimising coagulant dose whilst not impacting water quality. The current trial indicates a saving of around 30% in coagulant use can be expected if switching to automatic zeta potential control compared to approaches that do not measure zeta potential. Looking forward the




use on on-line zeta potential monitoring connects the physical operation with the mechanistic pathways by which it works and this opens up greater potential benefits in terms of quick diagnostic or emerging problems and adaptation to preventative maintenance approaches in the future. Acknowledgements The authors would like to acknowledge the support of Malvern Panalytical and Severn Trent Water during this work. References Jefferson, B., Sharp, E.L., Goslan, E.L., Henderson, R.K., Parsons, S.A. (2004) Application of charge measurement to water treatment processes. Water Science and Technology: Water Supply, 4(5-6), 49-56. Sharp, E., Borrill, B., Goslan, E.H., Jefferson, B. (2007) A mechanistic approach to predict disinfection by-product precursor removal during conventional coagulation. IN: Hahn, H.H., Hoffmann, E., Odegaard, H. (eds), Chemical Water and Wastewater Treatment IX, IWA publishing, London. Sharp, E.L., Crymble, S., Maher, K., Rowan, D. (2008) Zeta potential measurements render the floc test obsolete: Operation experience on a full scale works. In IWA conference – Natural organic matter: from source to tap. 2-4th September 2008, Bath, UK. Sharp, E.L., Rigby, R., Hughes, R., Claranino, J., Maher, K., Patel, K., Norris, R., Hall, A., Moore, K., Vaisman, A., Jefferson, B. (2016) Using online Zeta Potential measurements for full-scale coagulation control in drinking water treatment. IN: Particle Separation -2016, Advances in particle science and separation: meeting tomorrow’s challenges. 22-24th June 2016, Oslo, Norway.

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Application of Filta-Max Xpress for Cryptosporidium parvum detection in final drinking water, raw water and swimming pool waters Jennifer Greenhorn* Scottish Water, Juniper House, Heriot Watt Research Park, Riccarton, Edinburgh, EH14 4AP *corresponding author

Nathan Francis Scottish Water John Wood Scottish Water Jordan Howells Scottish Water Elise Cartmell Scottish Water

Abstract To help ensure public health protection there is a need to develop effective faster methods that will reduce positive detection reporting times for Cryptosporidium analysis. A Filta-Max Xpress machine and Filta-Max filters were tested using three water matrices including final drinking water, raw untreated water and swimming pool water. An elution procedure has been developed to rapidly and simply elute target organisms through the Filta-Max Xpress which uses air pressure to force an elution buffer though the filter. To assess Cryptosporidium recoveries each water matrix was tested using eleven 12L sample volumes which were spiked with 100c and 5c of C.Parvum respectively. The percentage recoveries were 45-46% for the 100c spiked samples and 40-60% for the 5c spiked samples. In the trial, it was demonstrated, that analysis times for different

water matrices with a turbidity range between 0.2- 0.5NTU could be reduced by 4-5 hours whilst still maintaining oocyst recovery. This supports the water sector to improve incident support and our customer experience. Keywords: Cryptosporidium, Filta-Max Xpress, swimming pool, raw water, drinking water, analysis time

Highlights •

4 -5 hour reduction in analysis time achieved.

Samples with turbidity within the ranges of 0.2-0.5NTU including swimming pool samples could be analysed.

Introduction It was in the 1980s that Cryptosporidium was first recognized as a cause of gastroenteritis outbreaks and its full impact became known. The recognition and subsequent spread of Acquired Immunodeficiency Syndrome (AIDS) left many people immunocompromised who were susceptible to cryptosporidiosis. This protozoan parasite was later found to occur in healthy subjects in particular children (Casemore et al 1985). Drinking water incidents and outbreaks elsewhere led to

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the development of regulatory requirements for drinking water treatment and analysis across the world (Chalmers 2014, DWI 1999, DWQR 2003). Swimming pool water also poses a Cryptosporidium risk. When monitoring began, between 1992 and 2011, 56 swimming pool outbreaks were reported in comparison to 32 outbreaks linked to public water supplies (Chalmers 2012). The publication Swimming Pool Water.

Treatment and Quality Standards for Pools and Spas (PWTAG 2006) and the WHO Guidelines for safe recreational water (WHO 2006) provide best practice guidance for swimming pool management and analysis. However, swimming pool water poses a problematic and often variable matrix to analyse which increases the current analysis time (7-8 hours) by up to 7 hours delaying sample results. Since the 1980’s Cryptosporidium

analysis methods have remained fairly stable and constant. To date analysis for Cryptosporidium involved using an IDEXX automatic wash station to wash filtered samples through Filta-Max filters prior the immunomagnetic stage followed by immunofluorescence microscopy. The washing stage alone can exceed an hour and therefore it is not uncommon to take up to 10 hours to wash 9 samples (Ferguson 2004). This time-consuming analysis is the limiting factor in detecting a fast result and improving incident response. An IDEXXFilta-Max Xpress machine and Filta-Max filters have therefore been trialled to reduce analysis time and report sample results faster for a range of waters. This paper outlines the methods followed to establish and validate Cryptosporidium analysis for drinking and swimming pool waters and reports on how analysis times could be reduced.

Materials and Method Sample locations and Procedure Samples were taken from a 40ML/day UK water treatment works (WTW) that carries out ozonation, rapid gravity filtration, chloraminated disinfection and pH correction. Samples were obtained from the inlet to the treatment works (raw water) and from the final outlet (final water). Swimming pool samples were obtained from a 25m UK public leisure pool. These samples had differing turbidity and colour: raw water 0.5NTU and 21mg/IPt+/co; final water 0.2NTU and <2 mg/IPt+/co; and swimming pool water 0.23 NTU and 0.55 mg/L Pt/Co. Samples were collected in clean 12L containers and refrigerated between 2.8 °C - 8.9°C until analysed within 72 hours. Eleven replicates were analysed for each matrix for low oocyst spikes of 5c and for a high oocyst spikes of 100c Cryptosporidium parvum (Master Stock sourced from University of Arizona, Sterling Parasitology Laboratory) with 22 results recorded for each matrix. Each 12L sample was pumped

through a Filta-Max foam filter (IDEXX Laboratories Inc. Westbrook, Maine) that uses multiple layers of compressed opencell foam discs to trap organisms, allowing field concentration of samples prior to the elution stage. A Filta-Max- Xpress machine was used for the elution stage taking 2 minutes regardless of water matrix. The filters were washed in 450ml of elution buffer Tween 20 in phosphate-buffered saline (PBST) (Vickers, UK). Samples were centrifuged down to create a pellet as the elution volume was 400ml after the final wash. A Thermo Fisher Scientific Multifuge X3F centrifuge was used at 1500g (Thermo Fisher Scientific, UK) for 40 minutes. The samples were then transferred into a 50 ml centrifuge tube (Corning Life Sciences, Polypropylene Rnase-/DNase-free nonpyrogenic) prior to a second centrifugation stage which took a further 40 minutes. The supernatant was then aspirated to c. 5ml (SCA 2010). The single sample processing time was c. 1 hour 15 minutes. Following the utilisation of the Filta-Max filters the existing method was then applied for the completion of the immunomagnetic stage (IMS) and immunofluorescent antibody staining using Anti Crypto Conjugated F.I.T.C and 4, 6 - DIAMIDINO - 2 - Phenyl Indole DAPI staining stock solution prior to immunofluorescence microscopy (MP18 - Isolation and Identification of Cryptosporidium oocyst in raw and portable water using compressed foam filters) (SCA 2010).

Results and Discussion In Figures 1 and 2 the mean recoveries of Cryptosporidium oocysts from the various water matrices are shown. For the 100c spiked samples recoveries were consistent across all three matrices ranging from 45-46 oocysts with an average standard deviation (SD) of 9 (Figure 1). The mean recoveries across the 3 matrices for the 5c spike samples were 2 oocysts for final samples, 2 oocysts for swimming pool samples and 3 oocysts for raw samples (Figure

2). The average mean ranges from 2 – 3 oocysts with the raw water recovery being the highest with a SD of 1. There was no significant difference in recoveries between matrices for low and high spikes P ≤0.113 and P ≤8.672. The raw water recovery for the lower spiked counts recovered the highest mean recovery however not a significant difference overall. The current methodology (MP 18) has an overall maximum loss of 60% (40% recovery) throughout the whole process dependent on water matrix, and loss through the IMS stage and DAPI/FITC staining stage. Recoveries have however been reported as being significantly higher between 76.9%-97.2% for raw water (Sartory et al 1998) with turbidity 6-19 NTU and up to 54.5% (McCuin and Clancy 2003). The results obtained in this study (45-46% for the 100c spike and 40-60% for the 5c spike) are within the expected % recoveries and were not reduced by the decreased elution time. Comparing the application of Filta-Max filters and Filta-Max Xpress machine with the current method which takes 7 to 8 hours to complete, the Filta-Max Xpress machines reduced the analysis time considerably by over 4 hours whilst maintaining the current consistent expected recoveries (≥40%). The combination of using Filta-Max filters with the FiltaMax Xpress machine results, therefore demonstrate a sufficiently effective and faster method for Cryptosporidium detection. Overall, further improvements to increase recoveries for example would be beneficial which could include the development of new materials that could be incorporated into the concentration and release stages controlling Cryptosporidium oocysts adhesion (Pavli et al 2016).

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Figure 1 - Mean average oocyst recovery of three water matrices initially spiked with 100c


Conclusion In Summary Cryptosporidium analysis is time consuming currently taking 7- 8 hours which requires a lot of hands on analysis time c. 6 hours. The use of FiltaMax filters and Filta-Max Xpress machines enabled a more rapid method to detect Cryptosporidium which reduced current hands on analysis time by c. 4 hours. This decrease in analysis time enables a higher throughput of samples providing faster results for customers and increases laboratory capacity ensuring incidents, and outbreaks, can be detected much earlier. Incorporating swimming pool samples into this trial also created broader capabilities in analysis to support the monitoring of swimming pools and the leisure industry as a whole. However, future developments to further improve analysis times and recoveries are still required.

Figure 2 - Mean average oocyst recovery of three water matrices initially spiked with 5c

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References Casemore, D.P., Armstrong, M., Sands, R.L. (1985) Laboratory Diagnosis of Cryptosporidium. J Clin Pathol, (38) P1337-134. Chalmers, R.M. (2012) Waterborne outbreaks of cryptosporidiosis. Ann Ist Super Santia, (48,4) P429-446. Chalmers, R.M. (2014) Natural History and Development of Drinking Water Regulations. Microbiology of Waterborne Diseases (Second Edition). P287-326. Drinking Water Inspectorate DWI (1999) Standard operating protocol for the monitoring of Cryptosporidium oocyst in treated water supplies to satisfy water supply (water quality) amendments regulations SI No.1524. (Available from: Drinking Water Quality Regulator DWQR (2003) Cryptosporidium (Scottish Office) 2003 Direction. Scottish Executive Information letters: 2/2000, 4/2001, 10/2001, 2/2003, 3/2003. Ferguson, C. Kaucner, C. Krogh, M. Deere, D., Warnecke, M. (2004) Comparison of methods for the concentration of Cryptosporidium oocyst and Gardia cyss from raw water. Can J Microbiol, (50) P675-682. IDEXX (2018) Filta-Max Xpress – Cryptosporidium and Gardia collection and recovery. IDEXX. Westbrook. Maine, US. McCuin R.M and Clancy.J.L. (2003) Modifications to United States Environmental Protection Agency Methods 166 and 1623 for detection of Cryptosporidium oocyst and Gardia cysts in water. Appl Environ Mirobiol, (69) P267-274. Pavli, P., Venkateswaran, S., Bradley, M., Bridle, H. (2016) Enhancing Cryptosporidium parvum recovery rates for improved water monitoring. Chemosphere (143) P57–63. Pool Water Treatment Advisory Group PWTAG (2009) Swimming pool water. Treatment and quality standards for pools and spas. Sartory, D.P., Parton. A., Parton. A.C., Roberts, J., Bergmann K. (1998) Recovery of Cryptosporidium oocyst from small and large volume water samples using a compressed foam filter system. Lett Appl Microbiol, (27) P318-322. Standing Committee of Analysts SCA (2010) The Microbiology of Drinking Water - Part 14 - Methods for the isolation, identification and enumeration of Cryptosporidium oocysts and Giardia cysts. Methods for the Examination of Waters and Associated Materials. Environment Agency. World Health Organisation WHO (2006) Guidelines for safe recreational waters. Volume 2. Swimming pools and similar water environments. Geneva.


Energy use and carbon emissions across an English wastewater network S.B. Velasquez-Orta*

Oliver Heidrich

David Graham*

School of Engineering, Newcastle University, Newcastle upon Tyne, NE1 7RU England, UK. *corresponding author

School of Engineering, Newcastle University, Newcastle upon Tyne, NE1 7RU England, UK. Tyndall Centre for Climate Change Research, UK

School of Engineering, Newcastle University, Newcastle upon Tyne, NE1 7RU England, UK. *corresponding author

Abstract Drinking and wastewater infrastructures are intrinsically connected, but they differ in terms of how energy is used and where CO2 is produced. In this research, energy consumption and CO2 emissions from the wastewater infrastructure located in the North East of England were analysed. The methodology used a life cycle analysis inventory approach, followed by an assessment of different retrofit options (e.g., BF vs AS ) and alternate technologies to guide decision-making. Results showed that the wastewater infrastructure used more energy than the water infrastructure due to energy required for treatment. Wastewater treatment accounted for 81%, 79%, 78% and 68% of overall energy used, for the wastewater system, in Northumberland, Tyne & Wear, Durham and Tees Valley, respectively. Counties with a preponderance of AS versus BF plants, such as Tees Valley, required significantly greater amounts of energy per wastewater treated than Durham County, which is dominated

by BF plants. Using AD to treat sewage sludge improved the overall energy balance, reducing energy use by about half, although AD only reduced net CO2 emissions by 2%. Shifting treatment technologies towards BF plants, could reduce energy use relative to current AS plants. When large changes are impractical for current networks due to investments, on-site biological and non-biological alternative routes, discussed here, could be available for retrofitting existing AS plants. Keywords: wastewater, infrastructure, carbon dioxide, energy use, retrofit, resources Acronyms: AD Anaerobic digestion, AS Activated Sludge, BF Biofiltration, COD Chemical Oxygen Demand, GHG Greenhouse gas, NE North East, NWL Northumbrian Water Ltd., WWTP Wastewater treatment plant

Introduction National actions to reduce carbon emission across Europe are evident (Reckien et al., 2018). In England, a commitment is made to reduce CO2 emissions by 80% by 2050 (1990 baseline) through the Climate Change Act (United Kingdom, 2008). However, achieving such ambitious targets will require substantial changes in delivering public services, including provision of drinking water and domestic wastewater treatment (Villarroel Walker et

al., 2017). Alternate treatment technologies are not fully developed, and actual CO2 emissions and energy use data from fullscale operations have been unavailable. In fact, inadequate and dependable data on the water and wastewater infrastructure is recognised as a major knowledge gap (Rothausen and Conway, 2011, Venkatesh et al., 2017); making it very hard to baseline emissions and energy use in current networks, which in turn, makes informed

strategic decisions difficult. This knowledge gap is closing (Byrns et al., 2012, Mcnamara et al., 2016), but the scale of mandated CO2 and energy reductions within the urban water infrastructure is massive and more is needed. Indeed a recent review showed that most benchmarking methods are of diagnostic nature and do not provide improvement strategies to increase wastewater treatment

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plant (WWTP) efficiencies (Longo et al., 2016).


Figure 1: Energy use for water and wastewater treatment in the North East of England. Data collected in the period of 2010-2011.

Drinking and wastewater infrastructures are intrinsically connected, but they differ in terms of how energy is used and where CO2 is produced (Villarroel Walker et al., 2017, Venkatesh et al., 2017). An initial assessment between water and wastewater energy use indicated that wastewater infrastructure consumed more energy per year (Figure 1).

The question is how to satisfy future CO2 emission and energy mandates in a world where existing infrastructure was not developed to minimise energy use or CO2 emissions. WWTPs have a typical life span of ~50 years for concrete structures and sewer lines are often designed for 80-100 years use (ASCE, 2011). Therefore, building

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Figure 2: System boundary and flow model used to compile the wastewater and sludge inventory.

System boundaries and emissions This study aimed to quantify energy use and CO2 emitted across a regional wastewater network (i.e., NWL) to examine the value of retrofitting existing WWTPs. However, it was first necessary to determine baseline energy and carbon flows in the network (in 2010) and energy inputs/outputs due to transportation, pumping and waste treatment activities were tallied from NWL data, and outputs were estimated for CO2 emissions to air, residual biosolids placed onto land, and liquid effluents discharged to receiving waters (Figure 2).

The wastewater infrastructure is more varied, ranging small decentralised collection and treatment options, which discharge to large collection networks spanning whole cities or regions, to the local discharge to sensitive receiving waters. Further, wastewater treatment technologies range from activated sludge (AS) to biofilters (BF) to tertiary technologies (e.g., for nitrogen (N) and-or phosphorus (P) removal) to algal-based systems, which can potentially reduce CO2 emissions (Nordlander et al., 2017, Cano et al., 2015). The chosen technology is usually an industrial and commercial decision, and not a political or regional planning one, as the decision depends on effluent load, plant age, installation and running costs, and other factors. Given such diversity, it is not surprising energy use and CO2 emissions vary widely among different wastewater treatment options (Corominas et al., 2013, Longo et al., 2016, Sturm and Lamer, 2011). Historically, chosen treatment technologies have primarily focused on achieving effluent quality targets, which has biased decision processes, for example, AS, which readily achieves high COD removal rates, but also uses much more energy.

Baseline, data collection and assumptions

low-energy WWTPs and-or sewers is not a practical option in many cases, and it may be more feasible to retrofit existing WWTPs to lower energy use and CO2 emissions, modifying existing assets. For example, most large WWTPs in the UK use AS for their secondary treatment step, which is energy-consuming due to active aeration in carbon degradation. However, if one could reduce carbon inputs to the existing AS plants, using lower pre-treatment options (e.g., BF), similar effluent quality could be retained for less energy (Cano et al., 2015); an approach used in industrial waste treatment (Ahammad et al., 2013). Retrofitting requires capital investment, but if such investment is strategic and considers economies of scale (i.e., retrofitting is most valuable in large WWTPs), considerable rewards could be reaped by reducing operational energy costs in a future where energy will be more expensive and penalties for not meeting emission targets are more costly (Manning et al., 2016).

For such change to occur, water companies and related stakeholders must have data on which to make investment decisions. Previous studies have been based on hypothetical design parameters and/or data from one or two selected WWTPs (Corominas et al., 2013, Cakir and Stenstrom, 2005, Shiu et al., 2017, Mcnamara et al., 2016). This research has worked with a major wastewater infrastructure provider Northumbrian Water Ltd (NWL) who provided actual operating data to optimise future wastewater treatment strategies. We analysed 87 WWTPs and 196 pumping stations across four counties in NE England to quantify energy use and CO2 emitted from actual operations across the network. Specifically, NWL data approximated baseline energy and CO2 conditions, and we then estimate d the impact of different retrofit options (e.g., BF vs AS) and alternate technologies to guide decisionmaking.

Indirect GHG emissions, such as nitrous oxide and methane, were not considered in this study. Further, previous work has shown about 80% of total energy and carbon impacts in WWTPs occurs in the biological treatment step (Emmerson et al., 1995). Therefore, we centred the inventory around bio-treatment processes most common within the NWL network (i.e., AS or BF). Data from 87 WWTPs (16 AS and 71 BF plants) and 196 pump stations was compiled for the analysis (Figure 3). The normalising unit for comparisons between energy and carbon flows was “per megalitre of treated wastewater�, which is consistent with standards set by European Council Directive 91/271/ EEC concerning wastewater treatment. Therefore, all transport, pumping and treatment contributions in our analysis were estimated relative to this baseline unit. Specifically, energy and CO2 used or emitted, respectively, were tallied or calculated from NWL data or literature values (where necessary) and are reported per wastewater volume treated. More background information and calculation details of this study are described in detail by Velasquez-Orta et al. (2018).

Figure 3: Regional map showing the location of the waste treatment plants, the pump stations and the two AD facilities. Numbers of treatment plants show the energy use by treatment process in KWh/year (Velasquez-Orta et al., 2018).

The WWTPs used in this assessment are managed by NWL and shown on Figure 3. In most cases, the WWTPs primarily receive domestic wastewater, but some WWTPs also

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receive industrial wastewaters, transported via combined sewage collection networks. Typically, each WWTP treats and discharges liquid effluents locally, whereas resulting sludge from local treatment is dewatered and transported to two central anaerobic digestion (AD) facilities within the region. Therefore, energy use/outputs and carbon emissions include those from the WWTP itself, wastewater pumping within the network, sludge transport to central facilities, and outputs at the AD sites. Details of these elements are summarised below.

Wastewater treatment plants and pumping stations Energy use data for WWTPs and pumping stations were provided by NWL for 2010. These data were directly reported, in this study, as energy used. However, CO2 emissions are not typically recorded; therefore, CO2 emissions were estimated based on measured energy use data, organic loading rates, and known stoichiometric relationships between organic matter degradation, CO2 and biomass production. Energy consumed was translated to CO2 emissions according to the emissions produced from the fuel mix used by Northumbrian Water’s energy supplier, this was estimated as 541 g CO2/kWh. This was directly used to obtain CO2 emissions for pumping stations. However, the wastewater treatment itself and sludge/biosolids digestion also included CO2 production levels from their biological processes. These were calculated by obtaining the CO2 production from known biological oxygen demands (as BOD; extrapolated from COD) due to organic matter in wastewater entering each plant (from NWL) using the method reported by Monteith et al. (2005). This method employs process stoichiometry and extraneous CO2 production from endogenous respiration. CO2 outputs included those from the core biological process (e.g., AS or BF) and from sludge processing, which assumed 30/70% CO2/ CH4 mixed biogas.

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Wastewater treatment plants using conventional treatment: activated sludge (AS) Typical NWL AS treatment plants consist of pre-screening, primary settling, biological treatment, secondary clarification and sludge dewatering. Wastewater flows first through preliminary processes includ ing bar and conveyor rag screens to remove larger solid debris. Based on NWL data, these processes produce sludge for transport that require eight vehicle loads per year per WWTP. After screening, the wastewater passes through grit chambers where small inert solids are removed, which across network, produces two transport-loads per year per WWTP. The wastewater then enters primary settling tanks, which are designed to remove the majority of settleable solids. The remaining (primarily) soluble organic matter is biodegraded in the AS treatment units. These units are often placed in parallel to permit operational flexibility, but also to sustain and control appropriate retention times for effective waste treatment. Sludge generated during secondary treatment is removed in secondary clarifiers, and the liquid supernatant is discharged to the environment in most cases.

Wastewater treatment plants using trickling filters: biofilters (BF) BF treatment plants include the same basic unit operations as AS plants, except fixedfilm bioreactors are substituted for the AS units. It should be noted that a variety of BFs are used across the NWL network, but we have homogenised the definition for the sake of simplicity, which is a reasonable assumption, given the diversity of BF plants across the network.


commercial plastic, both of which serve as a physical support for attached bacterial growth. In this type of process, effluent after primary settling enters a column or chamber where transverse contact occurs with biofilms on the solid media. Flow is sometimes gravity-based, but more often is under pressure (requiring pumping), frequently driving sprinkling arms that disperse the wastewater across the top surface of the BF. Treatment occurs as the waste trickles through the BF and effluents are typically passed to clarifiers like AS. However, the amount of sludge produced by BF units tends to be lower than AS (see below).

Sludge treatment and transport Two basic types of biological wastewater treated are common across the NWL network, but how much sludge was produced differ s according to controlling parameters. As noted, BF units tend produce less sludge because solids retention times tend to be longer as the organisms are attached in the reactors. Further, net biomass yields tend to be higher in AS units because of higher rates of active and lower endogenous decay. Most NWL WWTPs do not process their solids locally and local centrifugation units are used to concentrate sludge on-site, which is then transported to the central AD units. Specifically, concentrated sludge is stored open -top silos and carried as a wet slurry by six- and eight-wheeler diesel tank trucks to AD facilities in Howdon (within Newcastle upon Tyne) and at Bran Sands (near Middlesbrough, Tees Valley) (see Figure 3). We used Arc-GIS software to map transport paths related to the spatial arrangement of WWTPs and locations of the two AD units as central nodes. Vehicle data was available (i.e., 8-wheel (9.3 t/load) and 6-wheel vehicles (13 t/load) for sludge transport) and Arc GIS was used to estimate the mean vehicle travel-miles per region.

Energy and CO2 model Modelling equations, to estimate sludge and CO2 production, were input to Microsoft ExcelÂŽ 2010, along with energy data provided. The model ran by sequentially solving a series of equations (VelasquezOrta et al., 2018) placed according to the order of unit operations in wastewater treatment plants: 1) TSS and BOD removed in the first clarifier, 2) Total sludge produced and BOD removed in the aeration reactor, 3) Carbon dioxide produced in the aeration reactor from organic matter conversion and endogenous respiration, 4) Carbon dioxide produced from energy used. An additional excel sheet was used to obtain the energy used and CO2 emissions from sludge and biosolids transportation, according to data retrieved from ArcGIS.

Results and Discussion Energy use, sludge produced and CO2 emissions for all treatment plants across the network are summarised in Figure 4. For all three metrics, AS plants are located at the higher end and BF plants in the lower end of the charts. Only two AS plants, one in Tees Valley and the other in Tyne & Wear, were below the mean in terms of energy consumption; no AS plant was below the mean in terms of sludge production; and only one AS plant (located in Tyne & Wear) was below the mean relative to CO2 emitted. Calculations from the model showed that the NE region produced ~30,670 tonnes of dry biosolids (treated sludge), reused as soil conditioner in the agricultural sector, equivalent to ~76, 700 tonnes of sludge at 60% moisture.

Figure 4: Energy used and carbon dioxide produced for wastewater treatment per county in the North East (Velasquez-Orta et al., 2018).

Energy consumption and CO2 emissions in the wastewater network Current energy use and estimated CO2 emissions produced by different components of the wastewater network across the region are summarised in Figure 5. It can be seen that wastewater treatment plants require the highest amount of energy and produce the highest CO2 emissions,

followed by the pumping stations and finally sludge transportation. However, using AD to treat sewage sludge improves the overall energy balance, reducing energy use by about half, although AD only reduced net CO2 emissions by 2%. This is not surprising because AD produces biogas (mostly CO2 and methane) as products of anaerobic degradation with CO2 largely going to atmosphere and the combustible fraction being converted to electricity.

Figure 5: Total energy used and CO2 emissions produced per process in the North East wastewater network.

This is similar to the value of 75,900 tonnes per year reported by Byrns et al. (2012) for the NE Region in the same year and amounts to 2.1% of the overall sewage sludge produced in the UK, which was 1,400,000 tonnes of sewage sludge in 2010 (Defra, 2012).

As background, BFs in the NWL network usually comprise of packed solid media made from blast furnace materials or

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A comparison of the emissions produced and energy used by different plants across the wastewater network is presented in Figure 6. This analysis took into account the fact that there was a difference in the types of wastewater treatment employed in each county, which could influence energy use and CO2 emissions (Velasquez-Orta et al., 2018). For example, a higher fraction of wastewater produced in Durham is treated by BF plants than by AS plants. Conversely, Tyne & Wear treats more wastewater using AS than BF.

Figure 6: Energy and CO2 emissions in the North East Region wastewater network (VelasquezOrta et al., 2018). A) Energy used for WWT per region and process in the North East. Total and process values were obtained by dividing the overall energy use per county by the overall wastewater flow treated. Energy offsets by anaerobic digestion of sludge were considered in the values obtained.

Wastewater treatment plants were responsible for the highest fractions of energy consumed and CO2 emissions in all counties. Wastewater treatment accounted for 81%, 79%, 78% and 68% of overall energy used in Northumberland, Tyne & Wear, Durham and Tees Valley, respectively.

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The fraction of CO2 emissions attributed to wastewater treatment were similar among the counties, the highest being for Tyne & Wear (89%) followed by Northumberland (88%), Durham (87%) and Tees Valley (86%). AD helped reduce the net amount of energy use, but less so for CO2 emissions. Using AD to treat sludge decreased the net energy used by 56% in Durham, followed by Tyne & Wear (51%), Tess Valley (48%) and Northumberland (47%). The greatest energy savings were in Durham due to lower overall energy used for treatment and pumping. A lower proportion of energy savings for Tyne & Wear and Tees Valley were obtained by anaerobically digesting the sludge that was produced in AS treatment plants (Figure 6A).

Surprisingly, transportation contributed the lowest fraction of energy used in each county, even in Durham, which had a high number of smaller, decentralised BF plants; i.e., only 8% of total energy consumed for transportation. Other counties (Northumberland, Tees Valley and Tyne & Wear) used less than 3% of the total energy for transportation. The energy used in transportation was linked to CO2 emissions; therefore Durham produced the highest CO2 fraction (4% of overall, Figure 6-B). Energy used for pumping was, at least, one order of magnitude greater than for transportation. Pumping stations in Tees Valley and Tyne & Wear represented 31% and 20% of the total energy used, respectively, while pumping in Northumberland and Durham used 17% and 14% of the overall energy, respectively. This pattern correlated with the proportion of wastewater treated by activated sludge (Table 1); indicating that counties with centralised networks used more energy for pumping wastewater than counties using decentralised networks. CO2 emissions produced by pumping stations represented between 19% (for Tees Valley) to 8% (for Durham) the overall emissions for each county.


Discussions and conclusions

B) CO2 produced for WWT per region and process in the North East. Total and process values were obtained by dividing the overall CO2 emissions per county by the overall wastewater flow treated. Energy and carbon dioxide offsets by anaerobic digestion of sludge were considered in the values obtained.

This study compared energy and emission data among different operations and components in the NE region wastewater network, including 87 WWTPs and 196 pump stations. Overall, wastewater treatment itself was found to have greatest impact on CO2 emissions and energy costs. In particular, AS plants demanded considerably greater energy than BF plants, which is clearly reflected by differences in energy and carbon per wastewater treated across the region. Counties with a preponderance of AS versus BF plants, such as Tees Valley, required significantly greater amounts of energy per wastewater treated than Durham County, which is dominated by BF plants. Therefore, shifting treatment technologies towards BF plants and-or alternate options, such as anaerobic or photosynthetic waste technologies, could reduce energy use relative to current AS plants. In reality, such grand changes are impractical for most current networks as this would require substantial investments in providing the new infrastructure systems. However on-site biological and nonbiological routes could be available for

retrofitting existing AS plants and could be financially more viable (Velasquez-Orta, 2013). Manning et al. (2016) recently showed there could be a significant economic advantage to retrofitting existing AS plants with a BF pre-treatment step, which would reduce the carbon load on the AS plant, reducing aeration energy use. They suggest this would be particularly cost-effective in retrofitting larger WWTPs. Velasquez-Orta (2013) demonstrated that simultaneous cultivation of microalgae/ bacteria in aerobic tanks helped reduce CO2 emissions, increased nutrient removal and sludge energy content without compromising treatment. Wastewater treatment networks are engineered to remove pollutants from wastewater streams to a level that conforms to discharge quality standards and protects community health. However, as reducing CO2 emissions and energy consumption becomes more important, wastewater network design must now take into account additional sustainability factors. This work showed that counties with centralised wastewater networks not only use more energy for pumping wastewater, but also for treatment, especially AS technologies, whilst counties with greater BF plants for less energy and emit less CO2. These differences are critical and identify specific network inefficiencies that can be targeted for change. Reducing energy use during biological treatment, either through retrofitting or alternate technologies, will have the greatest positive impact on reducing CO2 emissions and energy use. Therefore, future development of wastewater infrastructures should help on these inefficiencies; i.e., reducing reliance on AS plants, increasing BF and alternate plants, and minimising new sewer construction, possibly via greater WWTP decentralisation. Acknowledgements We appreciate the technical assistance and industrial insight of different managers and specialists in Northumbrian Water Ltd including Mrs. Bernie Glanville, Mrs. Holly Hutchinson, Mr. David Harker and Mr Alec Llewellyn. An extended manuscript describing more details around this study has been published in Applied Energy (Velasquez-Orta et al., 2018). This work was partially supported by the EPSRC through the project titled: SECURE: SElf Conserving URban Environments (reference number: EP/I002154/1). EPSRC had no involvement in the study design;

collection, analysis and interpretation of data; writing of the report; or in the decision to submit this manuscript for publication with the Journal. References AHAMMAD, S. Z., BERESLAWSKI, J. L., DOLFING, J., MOTA, C. & GRAHAM, D. W. 2013. Anaerobic-aerobic sequencing bioreactors improve energy efficiency for treatment of personal care product industry wastes. Bioresource Technology, 139, 73-79. ASCE 2011. Failure to Act: The Economic Impact of Current Investment Trends in Water and Wastewater Treatment Infrastructure. Washington, USA.: American Society of Civil Engineers. BYRNS, G., WEATLEY, A. & SMEDLEY, V. 2012. Carbon dioxide releases from wastewater treamtnet: potential use in the UK. Engineering Sustainability - ICE publishing, 166. CAKIR, F. Y. & STENSTROM, M. K. 2005. Greenhouse gas production: A comparison between aerobic and anaerobic wastewater treatment technology. Water Research, 39, 4197-4203. CANO, R., PÉREZ-ELVIRA, S. I. & FDZ-POLANCO, F. 2015. Energy feasibility study of sludge pretreatments: A review. Applied Energy, 149, 176-185. COROMINAS, L., FOLEY, J., GUEST, J. S., HOSPIDO, A., LARSEN, H. F., MORERA, S. & SHAW, A. 2013. Life cycle assessment applied to wastewater treatment: State of the art. Water Research, 47, 5480-5492. EMMERSON, R. H. C., MORSE, G. K., LESTER, J. N. & EDGE, D. R. 1995. The life-cycle analysis of small-scale sewage-treatment processes. Water and Environment Journal, 9, 317-325. LONGO, S., D'ANTONI, B. M., BONGARDS, M., CHAPARRO, A., CRONRATH, A., FATONE, F., LEMA, J. M., MAURICIO-IGLESIAS, M., SOARES, A. & HOSPIDO, A. 2016. Monitoring and diagnosis of energy consumption in wastewater treatment plants. A state of the art and proposals for improvement. Applied Energy, 179, 1251-1268. MANNING, L. J., GRAHAM, D. W. & HALL, J. W. 2016. Wastewater systems assessment. In: HALL, J. W., TRAN, M, HICKFORD, A.J., NICHOLLS, R.J. (ed.) The Future of National Infrastructure: A System-of-Systems Approach. . Cambridge: University Printing House. MCNAMARA, G., FITZSIMONS, L., HORRIGAN, M., PHELAN, T., DELAURE, Y., CORCORAN, B., DOHERTY, E. & CLIFFORD, E. 2016. Life cycle assessment of waste water treatment plants in ireland. Journal of sustainable development of energy , water and environment systems, 4, 216-233. MONTEITH, H. D., SAHELY, H. R., MACLEAN, H. L. & BAGLEY, D. M. 2005. A rational procedure for estimation of greenhouse-gas emissions from municipal wastewater treatment plants. Water Environment Research, 77, 390-403. NORDLANDER, E., OLSSON, J., THORIN, E. & NEHRENHEIM, E. 2017. Simulation of energy balance and carbon dioxide emission for microalgae introduction in wastewater treatment plants. Algal Research, 24, 251-260. RECKIEN, D., SALVIA, M., HEIDRICH, O., CHURCH, J. M., PIETRAPERTOSA, F., DE GREGORIO-HURTADO, S., D'ALONZO, V., FOLEY, A., SIMOES, S. G., KRKOŠKA LORENCOVÁ, E., ORRU, H., ORRU, K., WEJS, A., FLACKE, J., OLAZABAL, M., GENELETTI, D., FELIU, E., VASILIE, S., NADOR, C., KROOK-RIEKKOLA, A., MATOSOVIĆ, M., FOKAIDES, P. A., IOANNOU, B. I., FLAMOS, A., SPYRIDAKI, N. A., BALZAN, M. V., FÜLÖP, O., PASPALDZHIEV, I., GRAFAKOS, S. & DAWSON, R. 2018. How are cities planning to respond to climate change? Assessment of local climate plans from 885 cities in the EU-28. Journal of Cleaner Production, 191, 207-219. ROTHAUSEN, S. G. S. A. & CONWAY, D. 2011. Greenhouse-gas emissions from energy use in the water sector. Nature Climate Change, 1, 210-219. SHIU, H. Y., LEE, M. & CHIUEH, P. T. 2017. Water reclamation and sludge recycling scenarios for sustainable resource management in a wastewater treatment plant in Kinmen islands, Taiwan. Journal of Cleaner Production, 152, 369-378. STURM, B. S. M. & LAMER, S. L. 2011. An energy evaluation of coupling nutrient removal from wastewater with algal biomass production. Applied Energy, 88, 3499-3506. UNITED KINGDOM 2008. The Climate Change Act. In: II, E. (ed.). UK: The Stationary Office Limited. VELASQUEZ-ORTA, S. B. 2013. Alternatives for energy produciton in aerobic wastewater treatment facilities. Water Science & Technology, 67, 2856-2862. VELASQUEZ-ORTA, S. B., HEIDRICH, O., BLACK, K. & GRAHAM, D. 2018. Retrofitting options for wastewater networks to achieve climate change reduction targets. Applied Energy, 218, 430-441. VENKATESH, G., BRATTEBØ, H., SÆGROV, S., BEHZADIAN, K. & KAPELAN, Z. 2017. Metabolism-modelling approaches to long-term sustainability assessment of urban water services. Urban Water Journal, 14, 11-22. VILLARROEL WALKER, R., BECK, M. B., HALL, J. W., DAWSON, R. J. & HEIDRICH, O. 2017. Identifying key technology and policy strategies for sustainable cities: A case study of London. . Environmental Development, 21, 1-18.

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The Compliance and Event Risk Index explained: The principles and practice of delivering innovative regulation in drinking water quality Marcus Rink

James Medland

Annabelle May

Chief Inspector of Drinking Water

Water Quality Data Officer

Principal Inspector

Jacqueline Atkinson

Caroline Knight

Principal Inspector


Abstract The Water Industry Act and The Regulations set out the duties and statutory requirements of water companies who supply drinking water to the public. The Drinking Water Inspectorate regulates and oversees these duties by demonstrating compliance through a measure called Mean Zonal Compliance (MZC). MZC in England and Wales has remained at 99.96% for the last twelve years, representing a high level of water quality. This paper describes the introduction of two new and innovative measures, CRI and the ERI, employing a proportionate methodology which prioritises on risk not used previously in regulation. These measures are described to show how they account for all failures and events and are not influenced by increasing the sample set of compliant data. The unique application of the hazard and likelihood assessment to identify those parameters or events which pose greatest risk to consumers is demonstrated by data analysis and graphical representation together with outcomes.

In the short, medium as well as the long term, companies will need to respond to the new measures to improve the score. To do this they will need to be innovative and resilient, will have to proactively manage and strategically plan. The outcomes are clear, consumers will benefit. In the short time these measure have been in place, there have been measurable improvements in both the numbers of those consumers affected and the duration of failures and events. Actions by companies have progressively reduced the score of both measures whilst no discernible change was apparent in MZC or event numbers. The alignment in using these measures between the water quality regulator, (DWI), the financial regulator, (OFWAT), and the companies themselves will continue to drive improvement to ensure that companies’ deliver safe clean and wholesome water now and into the future. Keywords: Compliance Risk Assessment, Event Risk Assessment, Mean Zonal Compliance, Water Quality, Compliance, Water Companies, Water Supply, Innovation, Resilience

Introduction The Water Industry Act 19911 and The Water Supply (Water Quality) Regulations 2016 (as amended) in England2 and 2018 in Wales3 (the Regulations), set out the duties and statutory requirements of water companies who supply drinking water to the public. The Drinking Water Inspectorate

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regulates the quality of water supplied by water companies in England and Wales, ensuring that drinking water supplies meet the requirements of the Act and the Regulations. This is delivered through the assessment of monitoring programmes and results, the technical audit of a range of

water company activities and assets that could affect quality and the investigation of any water quality events. The Regulations list parameters, which maybe chemical or microbiological, with their respective limit concentrations or

values forming the basis of compliance through water sampling and testing. This is a common measure used in regulatory compliance and in its’ simplest form it is a percentage of those tests which fail the standards set against the total number of tests carried out. Performance in England and Wales is described as Mean Zonal Compliance (MZC). This measure was first published in the Chief Inspector’s Report – Drinking Water 2004 and comprises the average of 39 different parameters for each water supply zone of up to 100,000 consumers that are tested at customers’ taps4 and from which the average of these zones is calculated across England and Wales to produce a country average. Since 2005, companies’ performance against this measure has remained largely unchanged at around 99.96%. Whilst this indicates a very high level of performance by companies, it does not provide an appropriate basis for strategic investment decisions required to address those parameters or assets which may present a higher risk to consumers. Furthermore, use of MZC ignores events where unwholesome water may have been supplied to consumers, as events do not form part of the routine compliance monitoring programme of randomised sampling set out in the Regulations. Events must be notified separately as these are unplanned incidents which require separate investigation. High profile events can severely inconvenience consumers, pose health risks, create potential to undermine trust in public water supply and the reputation of individual companies and are potentially damaging to the credibility of the sector. With no interrogative measures for this area other than the total number of events, strategic understanding of performance is lacking. In August 2015, a strategic programme was initiated by the Drinking Water Inspectorate (DWI) to introduce two new drinking water quality measures: the first, the Compliance Risk Index (CRI), allows companies to move away from the current monitoring programme (based on set sample numbers)

to a risk based monitoring methodology to assess compliance. The second, the Event Risk Index (ERI), allows companies to move away from the current event response categorisation to a risk based methodology which assesses the impact of events on consumers, and promotes proactive risk mitigation. This paper describes the new measures and the outcomes after three years of development and implementation by the Drinking Water Inspectorate (DWI).

Principles The basis of the measures builds upon the concept that all not compliance failures or events are the same. For instance, the detection of a faecal contamination, such as Escherichia coli, in drinking water would be considered more serious than perhaps an iron or manganese failure. Equally, the detection of an E. coli in a water treatment works is likely to be more serious than at a single tap, because whilst the failure at a tap remains serious and unacceptable for the consumers who use the tap, the failure at a works potentially affects a much larger population and presents a greater relative risk. Furthermore, when assessing failures or events it is necessary to consider the actions of the company since a satisfactory investigation with evidence of remedial action demonstrates a lower risk of recurrence compared to where there has been necessary intervention by the regulator such as in the form of recommendations or enforcement action. This incentivises the objective of reducing repeat occurrences and builds on the concept of the Act where the assessment of unlikely to recur is a duty on the technical assessor. Multiplying all these values together and adjusting for the company size provides an equitable understanding of company performance and exposes the areas of greatest risk focussing strategic direction. In creating this focus, short, medium and

long term actions which reduce the impacts of failures and events progressively reduce the measure and consequentially benefit consumers.

Prioritising outcomes Unlike MZC which attributes an equal value to each and every failure, CRI and ERI prioritises those failures and events which i. are serious in nature, ii. have required a greater level of regulatory intervention and iii. have affected a larger population for a longer duration. To ensure that risks associated with parameters and events are minimised, companies must direct corrective action by assigning a proportionately greater resource to those which are more serious, and, in the case of events, by reducing their impact by limiting both the time and population affected. This means that the motivation to employ “easy wins” to reduce numbers of failures by prioritising those that are easy to solve because they have an equal weighting to those that are not, is removed, and replaced by importance of that failure. For example, a failure of iron at the tap in MZC has the same weighting as lead at the same point. An iron failure is often associated with a failure of manganese and sometimes aluminium if deposits are re-suspended. Companies will employ distribution strategies to reduce these failures such a calm networks or flushing programmes and by doing such maintenance will improve significantly the MZC value by dealing with multiple failures in the same action. Whilst this is appropriate and should continue as ongoing maintenance, health parameters such as lead are not as simple as replacement of lead is expensive, can be difficult and failures are often property related. Companies minimise these failures by ongoing phosphate dosing programmes at works which minimises any effect on the MZC value and no further strategic objective is necessary. Likewise, two events are not the same and counting total events does not differentiate between a transient aeration due to for instance, a pump

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risk arising from water quality events where an unplanned occurrence or incident has happened. The strategic objective for their development aligns with the current risk based approach to regulation of water supplies used by the DWI. All compliance failures and events are assessed by DWI using the provisions of the Water Industry Act 1991 and with regard to DWI’s published Enforcement Policy7.

failure, with widespread contamination of the network with Cryptosporidium which may require a prolonged boil water notice and which at best will be of significant inconvenience and hardship to consumers and businesses or at worst illness in the community as a result. As a regulatory tool, CRI and ERI permits DWI to map individual failures, key events, company and country performance and exposes those zones, reservoirs, treatment works and companies which are underperforming and require further regulatory and company strategic planning.

These new measures were developed in consultation with water companies, following the principles of “better regulation” as set out in the Regulators’ Code8 and are intended to scrutinise company performance on the basis of their risk of failing to meet the requirements of the Regulations.

Risk Indices The Compliance Risk Index (CRI)5 is a measure designed to illustrate the risk arising from treated water failures arising from the scheduled programme of regulatory compliance samples and the Event Risk Index (ERI)6 is designed to illustrate the

The calculation assigns a value to: i. the significance of the parameter failing the standards or the seriousness of each drinking water quality event,


(the Parameter score or the Event Category score); ii. the cause of the failure, the company performance in the investigation of the failure or managing the event; and any mitigation put in place by the company and the resultant regulatory outcome (the Assessment score); and iii. the location of the failure within the supply system taking into account the proportion of the company’s consumers affected or the impact of each event – based on a simple measure of the population affected and duration in hours, (the Impact score). Both the Parameter or Event score and Assessment score are scored 1 to 5 which are multiplied together in a 5x5 grid as seen in fig 1. The Impact score is the population who potentially may receive water or the volume of water which has failed to comply with the standard and the duration affected by an event.

Fig 1: CRI assessment grid Parameter or Event Seriousness Score

Non Health Risk Indicator

Regulatory Impact


Health Risk Indicator

Health Risk

Score Value






Incorrect data Outside operational limits







Satisfactory investigation did not identify a cause - Trivial - Unlikely to Recur







Suggestions made







Recommendations made







Covered by a legal Instrument - Enforcement considered - Enforcement (ERI only)







Prosecution or Caution (ERI) - Enforcement (CRI only)







Assessment Score

Grid notes: The ERI assessment grid scores 5 for a prosecution or Caution as the maximum sanction available replacing the maximum sanction of Enforcement available in in the CRI grid. Enforcement for the ERI grid is grouped in 4 along with the existing assessment categories of Enforcement considered and covered by a legal instrument.

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The parameter score or the Event category score equates the significance or seriousness of the failure scoring 1 for a non-health risk indicator such as conductivity, where in the Regulations water should not be aggressive, or in an event where consumers have received water which is unlikely to have a health impact but are dissatisfied such as if they were to receive aerated water. The index progressively increases to aesthetic where for instance iron or manganese is detected or discolouration has occurred in an event up to a score of 5 for parameters such as E. coli, mercury or arsenic where the presence of these may pose a significant health risk or where consumers may have suffered harm following an event.

Fig 2: CRI and ERI equations

When assessing an event or a compliance failure, the actions of the company result in an assessment score. Where a company has carried out an investigation fully and all actions which could be reasonably expected to prevent a recurrence were taken then a score of 1 is assigned. This score increases if there has been a failure to meet the requirements of the regulations and recommendations are made attracting a score of 3 rising to a maximum of 5 if it was necessary to prosecute a company following an event because the assessment cannot show the circumstance is unlikely to recur due to the company action or inaction.

Equation notes: Impact for ERI is the sum of the population affected and the duration (in hours) consumers are expose

Water supply zones: CRI = (Parameter Score x Assessment Score x Population affected) (Total company population served) Treatment works, (and Supply Points, where samples can be taken at taps downstream instead of taking them at works): CRI = (Parameter Score x Assessment Score x volume supplied (m3/day) ) (Total daily volume supplied by the company (m3/day)) Service reservoirs: CRI = (Parameter Score x Assessment Score x reservoir capacity (m3/day) ) (Total service reservoir capacity of the company (m3)) Events: ERI = (Seriousness x Assessment Outcome x Impact) (Total population served by the Company)

to the risk.

Fig 3: CRI & MZC performance for England and Wales 2014 - 2017

The compliance CRI or the event ERI score is then calculated for each compliance failure or notified event using the formula in Figure 2. The CRI or the ERI for a company, for any given calendar year, is the sum of the individual CRI or ERI scores for every failure or event notified to the Inspectorate during the year. So, for example, a high performing company would ideally have a CRI score of zero as this would equate to no compliance failures but may consider an initial target to be in the best 25% of companies and set a value of less than 2 and a poor performing company may score in excess of 3.8 as this is above the national value. These values are relative to the performance of other companies and

may change from year to year. Similarly for ERI, companies should look to achieve a score of zero as this would equate to no impact upon consumers but may initially set a score of under 20 or 30 for a good performer, to over 250 for a poor performer since again this is above the national value. All compliance failures and events are assessed to ensure that the wellbeing and interests of consumers were protected by

best practice in management of compliance failures or an event. A well-managed response to a compliance failure or an event with appropriate and speedy mitigation action poses a lower risk to consumers. The DWI also considers the root cause of the failure or event and whether the company’s actions led to or increased the likelihood of the failure or event, and whether further remedial action is necessary.

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The Compliance Risk Index9

Fig 4: CRI parameter contribution for England and Wales 2017

CRI is a powerful tool which permits visualisation of country and company performance. A reducing value indicates improving actions by companies to reduce or manage failures so even whilst there has been a failure and consequently there is no change to MZC the impact of the failure to consumers is minimised by reducing the impact of the failure such as a reduction in the number of consumers affected. Since consultation with the water industry in 2015, water companies in England and Wales have responded by making improvements which has benefited consumers by reducing the overall risk they are exposed to as can be seen in Fig 3. When the contribution to CRI by individual parameters is mapped (Fig 4), it is evident that there are clear priorities for companies’ strategic planning. The biggest influence by far are failures at treatment works and service reservoirs, which contribute more than half the CRI value through the detection of coliforms and turbidity at these assets. Therefore companies must plan to improve these assets to reduce the impact of compliance failures.

Fig 5: CRI performance for individual companies – 2017

Taking company 21, it is possible to determine that the majority of their strategy must be focussed on remediating aging iron mains, whilst company 26 also having metals as a failing parameter - is struggling with coliform failures at treatment works and removal of manganese.

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Company 22 must continue to prioritise catchment work for pesticides and also consumer domestic systems where odour and lead are prominent in their individual profile. The regulatory strategy for DWI is to communicate these water quality priorities to companies for future planning as focussing the company on their specific priorities will ultimately benefit consumers. For instance, if company 22 targets iron failures, consumers are likely to have fewer instances of discoloured water. For company 26 investing their resources in works and reservoirs will result in a more secure supply reducing the likelihood of microbial contamination and for company 22 a reduced likelihood of water being supplied with a pesticide, all increasing consumer confidence and trust. Additionally companies will benefit from being more efficient as investment is targeted at areas of highest priority.

The Event Risk Index

Note: The National CRI is derived from the total sum of all failures in England and Wales divided by the country population

ERI like CRI is a powerful tool which permits visualisation of country and company performance, a reducing value indicating improving actions by companies to reduce or manage events even whilst there is no change to event numbers.

When examining individual company data (Fig 5) it is possible to determine the strategic priority for each company. For instance company 28 will need to plan improvement to their treatment works as a priority, whilst company 21 will need to plan network improvements. Finally, on CRI, parameter-specific contribution for a company can be derived to determine where a company is performing best or needs improvement (Fig 6).


Fig 6: CRI parameter breakdown for companies 21, 26 and 22 respectively - 2017

Since consultation with the water industry in 2016, water companies in England and Wales have responded by making improvements which have benefitted consumers. Also like CRI, ERI can be plotted to show improving industry performance by a decreasing value, (Fig 7). Whilst the overall numbers of events remains in the range 500 - 550, companies can reduce the seriousness of an event by proactive risk assessment and mitigation, or the impact may be reduced through expeditious action to reduce the number of consumers affected or by reducing the duration of the event. For instance, an event in a reservoir can be quickly mitigated by removing it from supply, or a network event through rezoning. The strategic planning for the resilience of operational assets should include measures such as removing single points of failure and providing alternative source arrangements.

Fig 7: ERI performance & total number of Events for England and Wales 2015 – 2017

Considering all 504 events of 2017, the proportion of events divided by seriousness and assessment score can be seen in Fig 8. The combined ERI value of those events where the seriousness was scored as 5, (72 or 14% of events), sums to about 50% of the total value. Similarly, when enforcement was taken, only 27 events (5%), (which included 12 events scored as 5 for seriousness), summed as two-thirds of the national ERI. The top 10 events accounted for 73% of the total ERI. Three of these events did not score a seriousness of 5. The single highest scoring event, responsible for 30% of the score on its own did not score a 5 for seriousness, was as a result of sub optimal pesticide removal processes which was unable to remove an

increased and known raw water challenge. This continued for nearly a month supplying nearly 400,000 consumers. Whilst the pesticide was not considered a health risk, the size, duration and inaction by the company contributed significantly to the overall score and emphasises why such events are likely to result in a higher score and most likely be associated with the consideration of enforcement. These high scores are intended to motivate companies to proactively act and self-regulate, completing actions prior to intervention by DWI. By doing this the scores will reduced and the impact on consumers will also consequently reduce by limiting the duration and number affected.

Fig 8a: ERI contribution by enforcement measures - 2017

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The analysis of the industry performance for ERI can take a similar form as CRI by plotting each company against the industry ERI, (Fig 9). However, since there are only around 500 events, the effect of a single large event which contributes to 30% of the score can influence the company ERI, as described in the example above and seen in fig 9 with a very high score for Company (A). When comparing companies’ performance, whilst it may be assumed that all those above the national ERI are performing worse than the industry as a whole, the single high scoring result, which has increased the national score benefits all other companies who may otherwise have been above the score otherwise. Similarly, a number of smaller companies who rarely have events will reduce the national score. To smooth for this variability, it is possible to take a three year average of the national ERI, (2015-2017), and use this for predictive calculations. If all things are equal and since there is a relationship between population and ERI, a division of the proportion of the population a single company supplies when compared to the national population results in an expected ERI for each company on historical data. For example; if a company supplies 10 million consumers in a country of 50 million then it would be expected to have contributed one-fifth of the national ERI, therefore, if the three-year average was 350, then the expected value for this company should be 70. Each company can then be plotted on a graph with their expected ERI, (X-axis), against their observed ERI, (Y-axis) and a line of best fit drawn, (fig 10 red line). Regression analysis is possible to draw a 95% limit of confidence from the data, (green line), providing clarity of performance. Companies A, B and C are above the 95% limit of confidence, are performing worse than the industry overall, and this is unlikely to be by chance. When considering Company (A), a breakdown of the individual contributing events can be charted and shown in

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Fig 8b: ERI contribution by seriousness - 2017

by company (A) continue to be exposed to more serious events linked to declining asset condition and maintenance. As an outcome, company (C) now requires less regulatory focus whilst company (A) is in direct line for enforcement activity to bring the company back on track.

Fig 10: ERI analysis for individual companies – 2017


Fig 9: ERI performance for individual companies - 2017 Note: The National ERI is derived from the total sum of all events in England and Wales divided by the country population

Fig. 11. This company experienced a detection of pesticides, a known risk, in water supplied to consumers from a single strategic treatment works, for a period of about a month. This was compounded by the failure of the granular activated carbon, (GAC), contactors, the only mitigation available, and the company had no alternative sources to enable the works to be removed from supply. Even though this failure was ongoing, the company exported non-compliant water to a neighbouring company. The importing company, and consequently their consumers, were paying for a product

which did not meet minimum specifications or expectations. The importance of ERI is to focus the forward strategy of both the company to remediating the root causes of events to prevent a recurrence, and consequently the regulatory duties to avoid the need for enforcement. Similarly, it can be used to track which company is improving or declining over previous years. Company (C) suffered a major incident in 2015 but through changes in strategy, focus and planning has taken steps to significantly reduce the number of serious events, whilst in comparison, consumers supplied

MZC in England and Wales has stayed firmly at 99.96% for the last twelve years. This clearly shows the water quality in England and Wales is of a very high quality. However, to continue improving it is absolutely necessary to drive innovation in the industry, so a new measure was required. The introduction of CRI and the ERI using seriousness and impact of each failure or event in a proportionate way, that accounts for outcomes and prioritises on risk, utilises innovative methodologies not used previously in regulation. In moving away from a measure such as MZC, which uses equal weighting for a limited scope of parameters, it not only accounts for all failures and events but is not influenced by increasing the sample set of compliant data. It is a unique application of the hazard and likelihood assessment to identify those parameters or events which pose greatest risk to consumers. Companies responding to the new measures to improve the score, must innovate, invest, maintain, proactively manage, strategically plan and most importantly must become more resilient. The outcomes are clear, consumers will benefit. The methodology is transparent and accountable, drives the right behaviour in those who are regulated and supports better regulation by being proportionate and targeted by the regulatory response. Equally, it drives the right behaviour by companies since action by companies must be directed to those failures which score highest in preference to those failures which may be easiest to resolve but benefit consumers the least. Most importantly, the introduction of a measure for events, for the first time, focusses on where things go wrong. In addressing the root causes of events this will seek to reduce

Fig 11: ERI for company (A) highlighting the events with greatest impact – 2017

Fig 12: ERI performance for most improving and declining performance 2015-2017

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direct and visible effects to consumers and ensure confidence in their water supply. In the short time these measure have been in place, there have been measurable improvements in both the numbers of those consumers affected and the duration of failures and events. Actions by companies have progressively reduced the score of both measures whilst there remains no change in MZC over the same period, however, continued and positive action to reduce CRI and ERI would be expected to have the beneficial effect of improving MZC as the objective is still to reduce failures overall.

Finally, the alignment in using these measures between the water quality regulator, (DWI), the financial regulator, (OFWAT), in their outcome methodology10, and the companies themselves, will continue to drive long term benefits from these measures to improve performance and ensure that companies’ investment strategies consider resilience in water quality to deliver safe clean and wholesome water now and into the future.


References 1. 2. 3. made 4. 5. CRI_Def.pdf 6. ERI_def.pdf 7. 8. uploads/system/uploads/attachment_data/file/300126/14705-regulators-code.pdf 9. 10. Appendix-2-Outcomes-FM-final.pdf

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Digital Transformation of Abstraction Licensing: Agile Innovation for Water Resources Management Andy Turner

Dr Jessica Bonham

Water Resources Manager Environment Agency

Delivery Manager Defra Digital, Data & Technology Services

Abstract With pressure on water resources set to increase due to climate change and population growth, it is becoming increasingly important to be able to make the most of every drop and to ensure that water is allocated effectively. Defra has published its Abstraction Plan1, setting out reform for water abstraction management over the coming years and how this will protect the environment and improve access to water. This paper describes the work being undertaken by the Environment Agency and Defra as part of the Abstraction Plan to transform its abstraction licensing business onto a digital footing so that the system will be more flexible, better able to meet the needs of customers, improve access to water and protect the environment. An ‘agile’ approach to development is being utilised, which is centered on user-needs and based on incremental delivery, releasing minimum viable products early so they can be used, tested and improved. Using this approach a digital platform that enables users

to view their licence details and submit abstraction returns online has been released and additional features, such as online access to river flows and levels are being added and improved. Future plans for the service include the facilitation of licence trading and dynamic catchment management. Keywords: Digital transformation, abstraction licensing, water resources, agile, Environment Agency, Defra

Highlights •

The abstraction licensing system is being transformed into a digital service.

The work is based on user-centered deign and an iterative and agile approach.

Users can view and manage their water abstraction licence details online.

Future work includes dynamic catchment management and online applications.

Introduction Water abstraction licences grant organisations or individuals a legal right to take water from the environment. They are issued by the Environment Agency2 following an assessment of impact on the environment and on existing abstractors. Licences often specify conditions for water abstraction including quantities, time of year and source of water abstraction as well

as the purpose that the water can be used for. Licences can also place restrictions on the amount of water abstracted based on the current water levels in the environment which are known as ‘hands-off flow’ conditions (HoFs). By monitoring and restricting the use of water in this way, the Environment Agency are able to protect the environment and ensure everyone gets a fair

and sustainable supply of water. With the licensing system’s roots in the Water Resources Act 1963, the current abstraction service is outdated and much of it is still paper-based. The Environment Agency is working with Defra Digital, Data & Technology Services to modernise the abstraction service and provide an online

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service for users to apply for and manage their water abstraction licences. The aim is to underpin work to improve both the environment and access to water by providing a modern and simple service for abstractors.


Figure 1: An overview of the planned components of the digital service

Unlike waterfall projects, where initial requirements are set out at the beginning of a project, and users do not normally get a chance to see what is being built until the project is complete, following this phased approach enables agile projects to be flexible, user-centred and ensures that teams can step back and assess the project’s success in-between phases.

Service overview The long term aim of the service is to deliver several areas of functionality, see Figure 1, which enable licence holders to: • View licence details • Access information on local water availability • Submit annual water usage data • Apply for / renew licences • Make trades with other users Whilst it is expected that this work will take several years to fully complete, the first stages of development went live in March 2018 and current licence holders can now view details of their licence online, submit records of abstraction online and can access some information on local river levels, see Figure 2. If you are a current water abstraction licence holder, the service can be accessed by searching for “manage water abstraction licence” online.

2. Understand user needs User needs are “the needs that a user has of a service, and which that service must satisfy for the user to get the right outcome for them”3 and have been at the forefront of delivery throughout this project. Figure 2: The current sign in page for the “manage your water abstraction or impoundment licence” service

An ‘Agile’ approach This project is following an agile approach, which is the standard for all digital projects within the UK government, as set out by GDS’s Digital Service Manual3. Some of the guiding principles of agile development and a description of how they have been followed in this project are detailed below.

1. Follow a phased approach Government digital projects are typically split into 6 different phases: • Discovery: research is undertaken to determine what problem the team are trying to solve, who the users are and what they need from the project. • Alpha: a prototype is designed and tested with users and feedback is used to improve the prototype. Business and

additional features outlined in Figure 1 and improve the service. Only when the continuous improvement of the service is complete will it enter the live phase.

technical requirements and constraints are identified. Private beta: the service is built and shared with a small, select group of users, where more feedback can be collected and used to improve the service. Public beta: the service is opened to the general public and updates and improvements are continuously made. Live: when development on the service is complete and the service is a high enough quality to meet the GDS standards, the service is moved into the live phase. Retired: when the service is no longer needed or is replaced by another service, it will be decommissioned.

Moving between phases allows the project team a chance to take a step back and decide if the project should progress and if so, the best route to take. At the end of alpha, private beta and public beta, the service goes through an assessment, where it is decided if the project is suitable to move onto the next phase. This ensures that the project is a high standard and that government funds are being spent on wellrun projects that are meeting user needs. The water resource licensing service entered public beta in March 2018, allowing all licence holders to gain access to the new service via the Government’s website4. During this phase the development team continue to build

In discovery, the team identified who the users were and spoke to them about their abstraction licences. By identifying how the current process works and how users feel about it, it is possible to understand what the users really need from a digital version of the service and how their current user journey can be improved. During alpha, and now in beta, the team are constantly testing the service with users, showing them new prototypes as they are being developed and taking the feedback that users give into account when building the service. By doing this the team can ensure that the needs of users are being met and that any new or evolving user needs are being captured.

As a service set up for the general public, the team also need to consider users who may not be comfortable using the digital service or who have accessibility requirements. To support these users, the Environment Agency’s National Customer Contact Centre has been brought on board to assist users over the phone. By understanding the user needs and collecting feedback, the team are ensuring that users enjoy using the service, would recommend it to other potential users and can get the desired outcome from the service on the first attempt. This will encourages more people to use the service to manage their water abstraction licences, which in turn allows the Environment Agency to better manage and protect water resources across the country. 3. Start small and iterate frequently Rather than designing a full working model and waiting to develop and deliver it, this work is being released in stages, where initially a minimum viable product (MVP) is designed, built and released. This provides early value to both the customer and the business and allows the delivery team to iterate and improve the service based on feedback they receive. A number

One such feature enables licence holders to view the river flows and / or levels which are linked to the conditions in their licences. This provides licence holders with better access to information, enabling them to plan for and manage their abstractions, make informed business decisions and reduce the risk of non-compliance with licence conditions. The MVP for this functionality allows licence holders with HoF conditions to see instantaneous flows and levels linked to their licence (as long as the water source is linked to an Environment Agency ultrasonic gauging station). This provides instant value to the user and is relatively quick to implement. As this service is iterated, the plan is to show daily mean flows and then recent or seasonal trends, see Figure 3, which users may find more valuable. In time, there may be a move towards showing forecasts of flows.

Figure 3: Prototype screen for recent trends shown in comparison with a hands off flow threshold.

The current service also has the option for users to leave feedback via a feedback bar shown at the top of the every page, see Figure 2. After being in public beta for 4 months, only a small proportion of users had provided feedback, so an exit survey was introduced, where users are asked to provide feedback when they log off the service. In a short amount of time, this new feature has significantly increased the number of users that provide feedback on the service. River level

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of functions added to the service have been designed using an ‘incubation’ style workshop, where stakeholders from across the business, users, and the whole delivery team have come together to design the MVP in matter of days5.

1st hands off level

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By working in this way, there is the opportunity to realise benefits earlier, rather than waiting until the full product has been developed. It has also provided an excellent opportunity to engage with users and to get their feedback on the future shape of the service. Working in an agile way also allows the team to be flexible about the order in which functions to the service are added. The work on river levels and flows was brought forward following a period of prolonged dry weather in England leading up to the spring of 2018. The team decided that users may need to use this feature over the summer and autumn so worked to release the MVP in early July, a well-calculated risk as June 2018 was the driest on record since 1925, and July was extremely hot and dry too.

A platform for future innovation The Environment Agency has embarked on its journey towards modernising the abstraction licensing service. The work that has been done so far has started to put the building blocks in place to replace legacy systems, reduce operating costs and improve resilience and efficiency. It is intended that this will provide a solid platform to enable a more active and dynamic approach to be adopted in the future. The incremental and agile approach is unlikely to stop with the basics. With pressure on water resources set to continue, there will be a continuing need for innovative policy thinking, improved flexibility in allocating water resources, and the ability for licence holders and 3rd parties to access and use data to help improve the way that water resources are managed. What could the future look like? It could include an approach which supports: Enhanced water rights trading With more information available online

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The best water in the world - it just runs off the hillside

there will be an enhanced ability to share and search for information on water rights and the willingness to trade. There will be the potential for 3rd parties to make use of this information and provide brokering services. There may be opportunities for simple, pre-approved trades to take place with little or no intervention by the Environment Agency. Dynamic catchment management The current service allows Environment Agency staff to send notifications to licence holders, advising them on the status of various conditions in their licence, including expiry of time limits and HoF condition notifications. As more licence holders register for and use the service and express a preference for electronic communication, a more dynamic approach to abstraction management can take place and, as confidence in the system increases, there could be automated notifications in the future. In time, there is also scope for the smart metering of abstraction quantities and an automated collection of records of actual abstraction, which would majorly improve the Environment Agency’s ability to monitor water usage and potentially support alternative approaches to allocation (such as water shares6). Evidence-led compliance inspections In parts of England, Environment Officers are already using technology such as satellite imagery to highlight moisture content changes in fields and crops where HoF conditions or irrigation restrictions are in effect, and can therefore detect where licence holders may be breaching the conditions of their licence. Innovative approaches such as this could quickly become the norm as this technology gets adopted more widely. The unknown We may have just started to scratch the surface of what is possible. By being open to ideas and feedback and actively listening to user needs, there may well be opportunities, where digital systems could support the transformation of water


Matt Bower Drinking Water Quality Regulator for Scotland 3F South, Victoria Quay, Leith, EH6 6QQ 0131 244 0743 resources management that we haven’t thought about yet. No matter what the future holds for this work, it will need the support and engagement of stakeholders and users and may depend on the appetite of abstractors, environmental organisations and policy makers. Some ideas may require a shift in culture, new legislation, and different levels of investment in monitoring or new technologies. Given the complexities associated with the development of new and innovative approaches to water resources management, the agile approach used in this project has helped drive its success so far and many of the features discussed above have the potential to benefit not just digital projects, but other disciplines as well. If you want to contact the water resource licensing service team or ask them about the current service please email water_ abstractiondigital@environment-agency. Acknowledgements The authors would like to thank Edward Power, Product Manager, Environment Agency, for helping to shape and proof read this paper. References 1. Defra, “Water Abstraction Plan policy paper,” 2017. [Online]. Available: water-abstraction-plan-2017/water-abstraction-plan . 2. “Managing Water Abstraction,” Environment Agency, 2016. [Online]. Available: publications/managing-water-abstraction. 3. “Digital Service Manual,” Government Digital Services, 2018. [Online]. Available: 4. “Manage your water and abstraction or impoundment licence,” Environment Agency, 2018. [Online]. Available: 5. “Defra digital blog,” 2018. [Online]. Available: https:// 6. Defra, “UK Government response to consultation on reforming the water abstraction management system.,” 2016.

Abstract Private water supplies (PWS) supply a small, but significant proportion of the Scottish population, especially in rural areas that can be far from the nearest public water supply. Many of these water supplies are managed by people with little technical expertise or awareness of the risks that contaminated water can pose for human health. The quality of PWS can vary, but is often poor due to inappropriate sources and inadequate treatment.

Local authorities are responsible for regulating PWS and administer a Scottish Government grant to enable owners to make improvements, yet the overall quality of PWS has not improved significantly. This paper explores potential reasons for this and what more might be done. Keywords: Private Water Supplies, Drinking Water Regulation, Scotland, Drinking Water Quality

The challenge of improving private water supplies in Scotland The quality of the public drinking water supply in Scotland is taken for granted by many, and rightly so – in 2017, 99.91% of tests on samples taken from consumers’ taps met the required standard. If you speak to many Scots, they will tell you that we have the “best water in the world”. The public water supply is indeed very high quality, however the image of pristine water running off idyllic hillsides belies the fact that such water sources require extensive treatment as they often contain microorganisms and are highly coloured, indicating high concentrations of natural organic matter. These present a problem for the many small, private water supplies in Scotland, but the users are often unaware of the risks.

Background In Scotland, private water supplies (PWS) are defined as any water supply not served by Scottish Water. There are over 23,000 such supplies, and they are the water supply for nearly 4% of the Scottish population. Many, but not all, are in rural areas beyond the reach of the public water main. For visitors to Scotland, they often crop up in tourist accommodation in some of Scotland’s most scenic areas. Legislation requires that such accommodation makes visitors aware that they are about to use a PWS, in the hope that such a measure will encourage establishments to ensure their supplies are safe to use.

A reasonably well designed and maintained surface water PWS abstraction in rural Scotland. Source DWQR

The distinction between private and public water supplies is certainly not one of size – the largest PWS supplies a community of 3,500, while the smallest Scottish Water supply serves two people. It seems to be a quirk of history that decided the current designation – when public water supply in

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Scotland was run by local authorities, it was a matter of local policy that decided which water supplies were adopted, and were later therefore transferred to the three public water authorities during the 1990’s and finally to Scottish Water when the Scottish Government owned water supplier was created in 2002.


Figure 1: Compliance for all samples taken from larger (Regulated) PWS in Scotland, year on year, with comparison against public water supply.1

Grant payments and advice have supported willing but uninformed PWS users, while enforcement action in a smaller number of cases has encouraged those who were, at first, less willing. Larger and commercial PWS are sampled at least annually by local authorities. The number of supplies where samples contain E.coli is of concern, as this indicates that the disinfection process is ineffective and other pathogens may be present.

An example of a PWS poster that is required to be displayed where PWS water is supplied to the public. Source DWQR

As Figure 1 shows, compliance with regulatory standards has improved little over the past seven years despite significant grant payments and concerted efforts by local authority staff.

Two PWS treatment systems, one supplying a large estate (Left), the other a simple “point of use” ultra violet disinfection unit in a kitchen cupboard. Source DWQR

Two PWS treatment systems, one supplying a large estate (Left), the other a simple “point of use” ultra violet disinfection unit in a kitchen cupboard. Source DWQR Regulation of PWS is the responsibility of local authorities, of which there are 32 in Scotland. The Drinking Water Quality Regulator (DWQR) has a supervisory role, which in practice often extends to a supporting one in terms of providing guidance and answering queries. The Scottish Government differs from the rest of the UK in that a grant is available to PWS owners to make any modifications that will improve the quality of the supply. The grant is administered by local authorities and is a maximum of £800 per property, although more is available in cases of hardship at the discretion of the authority. Individual grants can be pooled across a number of properties so that in larger communities a reasonably sizeable sum can be accrued. Although the grant

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is not designed to fully fund a complex multi-stage treatment process, it should cover a significant proportion of a simple ultra-violet disinfection unit. As well as providing practical support, the fact that the grant is available probably also serves as a useful “conversation opener” in cases where a PWS owner may not otherwise have engaged with the authority.

Compliance - Has anything got better? Improvements in PWS are hard to evidence at a national level, although on an individual basis there are many examples where local authority involvement has brought about considerable improvement.

Even compliant samples give limited reassurance as they are only a “snapshot” of water quality at a specific time and provide no confirmation that the water is wholesome at other times. The quality of water in many PWS in Scotland varies rapidly due to them consisting of, or influenced by, surface water and it seems highly likely that the analytical results do not tell the whole story. Additionally, the absence of E.coli does not guarantee the absence of pathogens such as Cryptosporidum, which, based on raw monitoring of public water supplies, is likely to be widely present. It is for this reason that DWQR and local authorities promote risk assessment as the most effective means of safeguarding water supplies on a continuous basis. Figure 2 shows 2017 compliance for just those parameters which fail most frequently on PWS, with the comparable figure for the public water supply. Besides microbiology, the other key group of failing parameters is pH and the plumbing metals. These are, of course, connected as many PWS do not have adequate water conditioning treatment and natural waters in Scotland tend to be low in pH and alkalinity, making them highly corrosive to metals, especially where poor quality or inappropriate materials have been used in plumbing.

Figure 2: Compliance for most commonly failing parameters in samples taken from larger (Regulated) PWS in Scotland, 2017, with public water supply comparison.1 Parameter

Total Samples Taken

Samples Failing PCV

% Compliance

% Compliance at Consumer Taps, Scottish Water

Coliform Bacteria










Hydrogen ion (pH)





E. coli















Clostridium perfringens

























It is always difficult to directly align poor water quality in PWS with actual cases of disease. Underreporting of diahorrheal diseases, numerous potential pathogen sources in rural areas and, in some cases, a transient population mean that evidence of a direct causal link can be hard to find. Risebro et al2 did not find a significantly increased risk of infectious intestinal disease in older age groups using poorer quality small water supplies, however there did appear to be a stronger link in those aged under ten. Research by the Drinking Water Inspectorate3 provides evidence of a link between PWS and outbreaks of disease, with twelve outbreaks between 2001 and 2009, but in many cases that link is “probable” rather than certain. Much evidence of risk therefore relies on anecdotal cases of illness attributed to PWS, of which there are a number.

What’s stopping us? While there is a strong political and health stakeholder desire to improve the quality of Scottish PWS, progress to bring about extensive and lasting improvements has been hampered by a number of factors:

Technology The most important element of any water treatment system is disinfection to inactivate pathogens. For PWS, the most common disinfection technique is ultraviolet light (UV) due to its simplicity and lack of need for chemicals. Unfortunately, to be an effective disinfectant, UV needs to be able to penetrate through the water. Many Scottish surface waters are high in natural organic material (NOM) which readily absorbs UV at the wavelengths commonly used to disinfect. This NOM can be relatively difficult to remove from water. Many of the large-scale traditional treatment processes used by Scotland’s publically-owned water supplier, Scottish Water, struggle to adequately remove it and require continuous optimisation in order to achieve satisfactory results. There are few reliable and simple small-scale treatment processes that are within the budget and capability of most PWS users. A simple, chemical-free treatment process to remove NOM on a small scale would be most welcome. Research undertaken by the James Hutton Institute, commissioned by DWQR4 found

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that disinfection using a standard UV dose of 40 mJ cm-2 was generally effective provided the UV transmittance of the water was greater than 75%. This is lower than had previously been thought, but still presents a technological challenge for some upland waters in Scotland.


A graphical illustration of the risks that PWS can present. A deer carcass at a PWS abstraction point. Source: Argyll and Bute Council

Attitudes One of the most difficult things to understand, and especially change, is human perception. While most people, if asked, would say water was a precious commodity, the reality is that provided it is reliably emerging from the tap and appears clean there is very little interest in its actual quality. People using PWS often harbour the perception that they are getting free water that does not contain the chemicals that they associate with the public water supply. Such perceptions often act as a barrier to people making improvements on their supply, especially where effort or expense is involved. People often seem unaware of the risks or choose to ignore them on the basis that they have been drinking the water for a long period without ill-effects. Such views are partly understandable but less acceptable where non-resident friends or relatives (or even paying guests) are regularly consuming the supply. And of course, risks and water quality can change rapidly, meaning a previously safe supply becomes contaminated. Where PWS serve communities rather than individual properties, attitudes of the community to their supply can vary. Work by Teedon et al for the Scottish Centre of Expertise for Waters (CREW)5 indicates that some communities are highly engaged with their water supply, but lack the expertise and support to make improvements. The study recommends that locally-specific approaches are developed with communities rather than adopting a “one size fits all” approach. Expertise Water treatment is a specialist area and beyond the expertise of many PWS users, even if they are interested enough to seek

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legislating that tourist accommodation shall display a notice informing visitors that they will be consuming water from a PWS. This is designed to initiate a conversation between visitor and landlord, and encourage the latter to ensure their PWS is well treated and monitored. Leafleting campaigns have been undertaken informing domestic PWS users of the risks and providing support, and local authorities contact thousands of PWS every year offering advice and grant support. It is hard to determine how effective any individual measure has been in raising awareness, but there is little doubt that publicising the risks form PWS is not a one-off task and needs to continue on an ongoing basis.

improvements. Safe drinking water on a continuous basis relies on the correct treatment process being identified, properly installed in the right location and maintained to ensure ongoing effectiveness. A deficiency in any one of these elements is sufficient to prevent effective performance. Robust water treatment systems are expensive, leading to a temptation to cut corners and adopt a “DIY” approach. The factors involved in the selection and installation of PWS treatment is currently the subject of research by the Consumer Futures Unit of Citizens Advice Scotland, supported by DWQR. Installers of PWS treatment equipment themselves may have varying levels of expertise. There are some reputable companies in Scotland with considerable expertise in PWS installations, but in some areas, especially the remoter regions, there is little choice apart from the local plumber. PWS regulation and advice is the responsibility of local authorities, yet resources devoted to PWS and corresponding ability to support PWS owners and users varies considerably

A leaflet that has been sent to users of domestic PWS to raise awareness of risks. Source: DWQR around Scotland.

What more can be done? Awareness Much work has been undertaken to raise awareness of PWS in Scotland, including

Connection Many PWS are in extremely remote areas with no prospect of connection to the public water supply, but for some PWS a Scottish Water main runs directly past the property. Connection to the public supply, with the safety and security it brings, is an option that should be encouraged. Barriers to connection include the cost of laying a supply pipe and connection fees as well as ensuring the connection requirements of Scottish Water are understood and complied with. The PWS grant is unable to be used towards the cost of connection for legal reasons, in some cases creating a slightly perverse incentive to people to remain on a PWS, albeit an improved one. In the longer term this situation needs to be resolved, but in the meantime work to better communicate the process that PWS users need to follow must proceed. Improvements to the planning process could also be helpful, to ensure that a wholesome and sufficient supply of water is a pre-requisite for allowing a planning application for a new-build property to proceed. Where a connection to the public system is feasible, this should be a requirement, in combination with checks post-build to ensure connection has taken actually place. Forthcoming changes to

Scottish planning legislation and guidance make this a possibility.


Support While progress is being made, it is clear that Scotland will always have a large number of PWS. It is vital that owners and users are supported so that those who are concerned about the quality of their water are helped to make improvements. A possible approach is to provide a service option, whereby PWS owners bring their supply up to a certain standard with support from the grant system where appropriate, then pay an annual sum, possibly equivalent to Scottish Water charges. This could provide a full service contract, emergency support and some assurance of water quality.

Users of PWS in Scotland are often unaware of the risks such supplies present, or choose to ignore them. Despite considerable efforts and financial expenditure over the past 12 years, it is hard to see significant overall improvements in the quality of PWS and compliance with the regulations. Although not entirely clear, evidence does suggest that many of these supplies present a risk to health that is unacceptable in modern Scotland, especially so where water is supplied to tourist accommodation and premises preparing or serving food. For those PWS owners and users who do want to improve their supply, it seems that some barriers can remain in terms of ensuring that the best overall solution for achieving sustainable high quality water is selected. It is vital that messages around risk and the need to manage PWS continue, alongside an enhanced package of support that can be adapted to suit the individual circumstances of PWS across Scotland.

Details, costings and delivery options for providers of such a scheme would need a considerable amount of development before such a scheme could become a reality. It is likely that, while some PWS users would welcome this choice, others would baulk at what would be perceived as an additional cost. A PWS treatment system will only provide comprehensive and lasting protection if it is installed correctly. Work to improve the skills and technical awareness of those who install PWS treatment systems needs to continue – this might extend to training courses, and accreditation schemes. Finally, there is much that owners and users can do to protect themselves by understanding and taking ownership of the risks that their water supply presents. A new risk assessment tool produced by DWQR will ensure that supplies are examined to a consistent standard. One of the outputs of the tool is a Drinking Water Safety Plan, tailored to the main risks that have been identified on that supply. Local authorities can choose whether to export a full DWSP or a simplified one, depending on the complexity of the system and capabilities of the owner.

References 1. Drinking Water Quality Regulator, Edinburgh September 2018, Drinking Water Quality in Scotland 2017 – Private Water Supplies, DWQR Annual Report 2. Risebro HL, Breton L, Aird H, Hooper A, Hunter PR (2012) Contaminated Small Drinking Water Supplies and Risk of Infectious Intestinal Disease: A Prospective Cohort Study. PLoS ONE 7(8): e42762. 3. Drinking Water Inspectorate, London, 2014 A Review of Incidence of Outbreaks of Diseases Associated with Private Water Supplies from 1970 to 2009 DWI Research Project Code 1269 4. Scottish Government / James Hutton Institute, 2016, Effect of Maintenance and different raw water quality parameters on ultraviolet disinfection in private water supplies in Scotland. Published on DWQR website 5. Teedon, P., Currie, M., Helwig, K., and Creaney, R. (2017) Engaging communities around private water supplies. CRW2014_12. Available online at

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Turn off the Tap: Behavioural messages increase water efficiency during toothbrushing Charles R. Seger

Ellin Lede

Andrew Brown

Corresponding author School of Psychology, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, United Kingdom. Email: Telephone: +44(0)1603 591398

Tyndall Centre for Climate Change Research School of Environmental Sciences, University of East Anglia

Anglian Water

Rose Meleady

William Davies

School of Psychology, University of East Anglia Centre for Behavioural and Experimental Social Science

Anglian Water

Sandra Bogeleina School of Psychology, University of East Anglia Tyndall Centre for Climate Change Research

Nick Sexton

Reducing consumer demand is part of a multidimensional strategy to increase water resilience. Theory-based ‘nudges’ or behaviour-change strategies may be effective at reducing demand at little cost. This paper reports a unique partnership between GlaxoSmithKline, water utility Anglian Water, and researchers at the University of East Anglia. Two experimental studies drawing on the strengths of these organizations investigated a behaviour change intervention designed to reduce water usage when toothbrushing. Study 1 tested the efficacy of three theory-based behavioural messages (social norms, ingroup norms, and collective efficacy) designed to encourage participants (N = 164) to turn off the tap whilst brushing teeth. In an actual toothbrushing scenario, all three messages proved to be effective compared to a no-treatment control condition. In study 2, homes in Newmarket, Suffolk (N = 382) were given toothbrushing packs containing a collective efficacy message that highlighted turning off the tap while toothbrushing. Smart-meter recorded water usage was obtained for three weeks before and three weeks after receiving the toothbrushing packs. Household water usage significantly decreased after receiving the packs. A control group of N = 382 households did not show a significant decrease in water usage during this timeframe. These

Anglian Water

Paul Barnett Centre of Excellence for Environmental Sustainability, GlaxoSmithKline

Anglian Water


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Sarah Castelvecchi

studies suggest that behavioural messages from public or private companies can be effective in reducing real-world water usage while toothbrushing. This model of collaboration between industry, water utilities, and academics can serve as a model of best practice for public and private companies interested in reducing household water usage. Keywords: Cwater efficiency, collaboration, behavioural messaging, nudge, toothbrushing, smart meters

Highlights •

A unique public-private partnership increased consumers’ water efficiency

Two experimental studies showed the efficacy of behavioural messaging

Study 2 demonstrates how messaging on products can increase efficiency in the home

This work demonstrates how interested stakeholders can effectively collaborate

Background Ensuring a sustainable water supply requires a multifaceted approach. Behaviouralbased approaches to encourage residential water efficiency can form an integral part of demand reduction strategies. However, far less attention has been paid to investigating water-related behaviour change interventions compared to interventions surrounding residential energy consumptions or recycling (Lede & Meleady, 2018). Public and private companies are increasingly interested in effective solutions that decrease water demand. The paper describes a public-private partnership with the goal of delivering and testing simple, cost-effective behaviour change messages that increase residential water-saving behaviour. The research reported here was created through an innovative collaboration between Anglian Water, GlaxoSmithKline (GSK), and academics at the University of East Anglia (UEA). Anglian Water is a water utility that supplies water to 4.3 million customers across an area of 27,500 square km in the East of England - one of the driest regions in the country, with as little as 600mm of rain annually. To meet the increasing demand for water, and to reduce the pressures on water resources and the environment, Anglian Water are committed to driving the latest innovative technologies and approaches throughout their business and supply chain. GSK is a pharmaceutical company that makes a variety of health care products, including Aquafresh brand toothpaste. GSK has aggressive commitments for reducing water usage across its entire value (“Our Planet Commitments,” n.d.). Consumer use accounts for nearly 13% of GSK’s value chain water footprint, mostly from cleaning teeth (“Water,” n.d.). Leaving the tap running while toothbrushing wastes over 24 litres of water a day, if brushing twice a day for two minutes (“Save Water,” n.d). With this in mind, GSK and Anglian Water approached researchers at UEA to develop simple, cost-effective behaviour change messages (or ‘nudges’) capable of reducing consumers’ water usage while

toothbrushing. Two initial studies tested the efficacy of different theory-based messages in reducing toothbrushing water usage, and a third used the unique strengths of GSK and Anglian Water to rollout this message to homes in Newmarket, England.

Literature Review

research, communicate the number of people who are already engaging in a behaviour (e.g. “80% of people in the UK reuse their plastic bags on a regular basis”). Goldstein, Cialdini and Griskevicius, (2008) found that changing a hotel’s standard informational appeal to a descriptive social norms message resulted in a 26% reduction in the number of towels washed (see Figure 1).

Human decision-making can be strongly affected by simple changes to the environment or the way information is presented. Because people often rely on fast and intuitive decision-making strategies, even very minimal cues or ‘nudges’ can have a powerful influence on behaviour (Dolan et al., 2012; Thaler & Sunstein, 2008). A growing amount of evidence argues that simple informational requests, whether related to environment, health or safety, generally does not lead to a change in behaviour (McKenzie-Mohr et al., 2012; Schultz, 2011). Instead, it can be far more effective to appeal to the underlying motivational basis for behaviour. In this research we explored how three different types of messages based on psychological theories of behaviour change may be successful at motiving people to turn off the tap when brushing their teeth: social norms, ingroup norms, and collective efficacy. Social Norms approach A powerful way of encouraging uptake of a behaviour is to highlight that it socially approved, or that many other people are already partaking in the behaviour. Such normative messages are used as a standard to judge and guide one’s own behaviour (Cialdini, Kallgren, & Reno, 1991). For example, Richetin and colleagues (2016) asked participants to wash their hands under the guise of a product-testing task. For some participants the soap dispenser was printed with a normative message indicating that most people turn off the tap when lathering. These individuals turned off the tap in greater proportions, and used less water overall, than those viewing a control message about the product. Descriptive norms, used in the current

Figure 1. Examples of the messages used by Goldstein et al (2008). Ingroup Norms approach The ingroup norms approach is similar to the social norms approach but rather than

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providing information about the behaviours undertaken by other people in general, it focuses on the norms of behaviourallyrelevant groups. According to social identity theory (Seger et al 2009; Tajfel, 1974) an important part of the self-concept is derived from memberships in social groups or categories; individuals define themselves not only in terms of their personal traits (e.g. ‘I am athletic’), but also in terms of their group memberships (e.g. ‘I am a Northerner’). When an individual thinks about themselves in relation to a specific group membership (or an ‘ingroup’), group members tend to think and act less as autonomous individuals and more in ways that are influenced by group norms and stereotypes. It follows that if proenvironmental ingroup norms are made salient (e.g. “UEA students save water”) individuals’ behaviour will assimilate to those norms (e.g., “I am a UEA student, therefore I should save water”). Player and colleagues (in press), for instance, found that road signs appealing to group norms increased the number of car drivers turning off their engines at a long-wait stop. Lede, Meleady and Seger (2018) provide ample evidence that an ingroup norms approach can reduce water consumption. In one study, stickers with either social norms or ingroup norms messages were put showers at a university accommodation (see Figure 2). Self-reported shower time in the ingroup norms condition was significantly reduced compared to both the standard social norms condition and a no-treatment control condition. Collective efficacy approach Self-efficacy refers to one’s belief in their ability to achieve a given goal through their actions (Bandura, 1977). Low self-efficacy represents a significant barrier to action on environmental problems. People often believe they cannot do anything about environmental issues as individuals, and therefore are not motivated to change their behaviours (Axelrod & Lehman, 1993). However, feelings of collective selfefficacy - the belief that one’s social group can effect change or reach a goal - can increase pro-environmental behaviour. Similar to the ingroup norms approach,

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Figure 2. Waterproof stickers used in the social norms condition (left) and the ingroup norms (right) in Lede et al. (2018).

details. Participants were fully debriefed upon conclusion of the study.

Figure 3. Experimental messages used in Study 1.

Results First, we checked whether participants noticed the behavioural messages. Despite their prominent placement in the participant’s visual field, nearly 30% of participants did not report noticing a message. Across all conditions (including the no message control), participants who read a message were significantly more likely to turn off the tap (97% turn off) when brushing their teeth than those who did not (73%; X2 = 14.94, p < .001).

people will be more likely to engage in a behaviour when they believe their social group can make a difference. For example, Jugert and colleagues (2016) presented individuals with a message that their social group were working together to promote environmentally-friendly behaviour and that it was having an impact. This manipulation significantly increased pro-environmental intentions amongst group members. Showing that the members of a social group can combine to have a large and concrete effect (e.g., “If British adults reduced their shower time by one minute, we would save enough water in a year to fill Wembley Stadium 130 times!”) may be particularly effective. The current research consists of two studies, both with the goal of increasing consumers’ water efficiency while toothbrushing. The first study compares the efficacy of the three approaches above on actual toothbrushing behaviour, using a community sample. Study 2 takes advantage of GSK and Anglian Water’s unique strengths by applying our messaging to measured water usage in Newmarket, England. All studies reported here received ethical approval from UEA, Anglian Water and GSK.

Study 1 Method Participants were 164 Norwich residents (51.8% female, Mage = 41.28 SDage = 17.34) who were recruited from the Millennium Forum in Norwich, Norfolk. Participants received £3, Aquafresh toothpaste and a toothbrush for their time. Experimenters from UEA approached people and asked if they would like to participate in a short study examining perceptions of toothpaste. Upon agreement, participants were brought to a private washroom where they were presented with a new toothbrush sitting in a clean cup holder, a tube of Aquafresh toothpaste, and a clean empty plastic cup for rinsing. On the washroom mirror, at eye level, participants were presented with one of the three message types outlined above (see Figure 3), or a no message control condition. Participants were left alone to brush their teeth. To record whether participants turned off the tap when brushing their teeth or not, a hidden audio recorder was placed under the sink (for similar methodology see Richetin et al., 2014). Participants then completed a brief questionnaire measuring their attention to the messages and demographic

When statistically controlling for whether participants recalled reading a message, pairwise comparisons demonstrate that all three experimental conditions increased the proportion of people turning off the tap compared to the control (social norms p = .006; ingroup norms p = .040; and collective efficacy, p = .002). None of the experimental messages significantly differed from each other. Raw percentages of people turning off the tap are presented in Figure 4. We also analysed the percentage of time the tap was on while toothbrushing (see Figure 5). Controlling for whether participants read the message, differences between conditions are significant, F(3, 156) = 2.28, p = .081. Pairwise comparisons show that compared to the control condition, both the social norms (p = .026) and collective efficacy (p = .025) messages reduced the percentage of time the tap was running.

Figure 4. Percentage of people turning off the tap while toothbrushing by condition, Study 1.

Figure 5. Percentage of time water was running by condition, Study 1.

This study demonstrates that behavioural messaging can increase water efficiency while toothbrushing and is in line with other recent research in this domain (e.g., Lede et al, 2018). Although this study measured the duration of water usage, it did not measure actual water usage or how such messages may work in the home. Study 2 investigated these issues.

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Study 2 Whilst Study 1 provides clear evidence for the efficacy of our theory-based messaging, the strongest test for such interventions is whether they reduce actual water usage in the home. Previous research has largely been unable to test this, but innovative Smart Meter technology demonstrated by Anglian Water allows us to examine this critical question with greater visibility and granularity of household water usage than ever before. Study 2 examined whether behaviourallyinformed messages could reduce measured household water usage. This field study made use of the Anglian Water’s Innovation Shop Window area in Newmarket, Suffolk. The Shop Window is a real location in which innovation is driven through collaboration between Anglian Water, its supply chain and interested stakeholders and companies. Currently, Anglian Water is working with over 105 partners in their Shop Window to test innovations across the entire man-made water cycle, including Smart Meter technology and behavioural change. In this study, a behaviour-change message was printed on free toothbrushing products delivered to households in the Shop Window area. Method Free ‘Turn off the Tap’ packs containing a toothbrush, Aquafresh toothpaste, a toothbrush holder and stickers were distributed to 382 households in Newmarket across seven dates from 11th November 2017 to 16th January 2018. The toothbrush holder and stickers were branded with the collective efficacy message like the one used in Study 1 (Figure 6). We chose the collective efficacy message because, although not statistically significant, the trends in Study 1 suggest that this message was most effective out of the three messages tested. Daily Smart Meter water readings from the households that received the packs (intervention group) were taken in three weeks before they received the pack (preintervention period) and three weeks after they received the pack (post-intervention

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Figure 6. Stickers used for the intervention in Study 3.

period). Smart meter readings were also taken, across the same timeframes, from a control group of 382 households that did not receive the intervention pack. These control households were also in Newmarket, mostly on neighbouring streets. Tables 1 and 2 show that socio-economic status and household size were broadly comparable between the intervention and control groups.

Table 1. Percentage of households in each Acorn category, Study 2. Intervention


Affluent Achievers



Rising Prosperity



Comfortable Communities



Financially Stretched



Urban Adversity



Information missing



Note: Acorn is a market segmentation tool which categorises the United Kingdom’s population into demographic types. For more information, visit

Table 2. Household size in Study 2. Number of occupants















5 or more



Information missing



Results On average, households in the intervention condition consumed significantly less water per day after receiving the intervention pack compared to before, Mchange = 7.57, t(379) = 2.411, p = .016. There was no significant difference in the amount of change between Acorn categories, (F(4, 344) = 1.421, p = .226) or between households of different sizes, F(4, 344) = 1.046, p = .383. The reduction in water consumption for control households was not significant, Mchange = 3.19. Pre and intervention means are presented in Table 3. A further statistical test was conducted to examine whether the amount of change for the intervention households were greater than the amount of change for the control group. No significant differences were found. One potential issue that increased variance and reduced the likelihood of finding statistical significance for this test is that for many households the timeframe of water meter data included the Christmas holidays and a period of vacation. However, the direction and magnitude of the effect suggests this intervention could lead to a significant increase in household water efficiency.

Summary and Conclusions Three studies demonstrate that theorybased messages can increase water efficiency during toothbrushing. Such simple ‘nudging,’ when applied to a large

Table 3. Pre and post-test means for the intervention and control groups, Study 3. Intervention Households (N = 382): Pre-intervention


Net Change

258.81 litres/day

251.24 litres/day

7.57 litres/day



Net Change

230.15 litres/day

226.96 litres/day

3.19 litres/day

Control Households (N = 382):

scale, can have a large effect for very little cost. Whilst collective efficacy messages were used in Studies 2, social and ingroup norms messages were also effective in Study 1. The final study shows promise that a collective efficacy message increases household water efficiency in the field. Collaborations between researchers and industry are essential for maximising the potential of behaviour change interventions that encourage climateresilient water behaviour (Lede & Meleady, 2018). The partnership here between Anglian Water, GSK and UEA serves as an excellent example. It provided tangible benefits to each organization and can be used as a model for other stakeholders in the water domain. Working with university researchers to test the effectiveness of water-saving messages removes guesswork and frees resources for service providers. Not only can social scientists offer techniques to change behaviour, they also offer methods (e.g. randomised control trials) to properly evaluate interventions and determine their overall impact. The partnership with GSK allowed Anglian Water a unique and effective way to deliver their messages in Study 2 while providing market penetration for Aquafresh.

Bibliography Axelrod, L. J., & Lehman, D. R. (1993). Responding to environmental concerns: What factors guide individual action? Journal of Environmental Psychology, 13, 149-159. Bandura, A. (1977). Self-efficacy: toward a unifying theory of behavioral change. Psychological Review, 84, 191-215.Cialdini, R. B., Kallgren, C. A., & Reno, R. R. (1991). A focus theory of normative conduct: A theoretical refinement and reevaluation of the role of norms in human behavior. Advances in Experimental Social Psychology, 24, 201-234. Dolan, P., Hallsworth, M., Halpern, D., King, D., Metcalfe, R., & Vlaev, I. (2012). Influencing behaviour: The mindspace way. Journal of Economic Psychology, 33(1), 264-277. Goldstein, N. J., Cialdini, R, B., & Griskevicius, V. (2008). A room with a viewpoint: Using social norms to motivate environmental conservation in hotels. Journal of Consumer Research, 35, 472–482 Jugert, P., Greenaway, K. H., Barth, M., Büchner, R., Eisentraut, S., & Fritsche, I. (2016). Collective efficacy increases proenvironmental intentions through increasing self-efficacy. Journal of Environmental Psychology, 48, 12-23. Lede, E., & Meleady, R. (2018). Applying social influence insights to encourage climate resilient domestic water behaviour: Bridging the theory-practice gap. Unpublished manuscript. Lede, E., Meleady, R., & Seger, C. R. (2018). Optimizing the influence of social norms interventions: Applying social identity insights to motivate residential water conservation. Unpublished manuscript. McKenzie-Mohr, D., Lee, N. R., Kotler, P., & Schultz, P. W. (2011). Social marketing to protect the environment: What works. Thousand Oaks, CA: Sage Publications. Our Planet Commitments (n.d.). Retrieved from https://www.gsk. com/en-gb/responsibility/our-planet/our-planet-commitments/ Richetin, J., Perugini, M., Mondini, D., & Hurling, R. (2016). Conserving water while washing hands: The immediate and durable impacts of descriptive norms. Environment and Behavior, 48, 343-364. Schultz, P. W. (2011). Conservation means behavior. Conservation Biology, 25, 1080-1083. Seger, C. R., Smith, E. R., & Mackie, D. M. (2009). Subtle activation of a social categorization triggers group-level emotions. Journal of Experimental Social Psychology, 45, 460-467. Tajfel, H. (1974). Social identity and intergroup behaviour. Information (International Social Science Council), 13, 65-93. Thaler, R. H., & Sunstein, C. R. (2008). Nudge: Improving Decisions About Health, Wealth, and Happiness. New York: Penguin. Player, A., Abrams, D., Van de Vyer, J., Meleady, R., Leite, A., Randsley de Moura, G., & Hopthrow, T. (in press). “We aren’t idlers”: Using subjective group dynamics to promote prosocial driver behaviour at long-wait stops. Journal of Applied Social Psychology. Save Water. (n.d). Retrieved from save-water/ Water. (n.d). Retrieved from responsibility/our-planet/water/

We recommend that other public and private companies look to form such collaborations as they can create unique products and opportunities at minimal cost that highlight the strength of every organization involved.

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Our editorial panel Robin Price CSci Vice President Science, Institute of Water Head of Water Quality, Anglian Water

The Institute of Water was founded in 1945 and is the only professional body which caters exclusively for the UK water sector. Our vision is for the UK water industry to be served by the best people. Our aim is to inspire our members to reach their potential through learning, networking and professional development.

Our members are committed to the water industry and its customers, to our vision and values and to developing their careers. We are inclusive and non-hierarchical and our members are drawn from water companies, suppliers, contractors, consultants and regulators. Membership offers anyone who works in water (regardless of their qualifications or discipline/department) the opportunity to broaden their knowledge and develop within the sector.

Benefits of membership include: Professional Registration We are licensed to award Professional Registration in Engineering (Chartered Engineer, Incorporated Engineer, and Engineering Technician), Science (Chartered Scientist, Registered Scientist and Registered Science Technician) and Environment (Chartered Environmentalist and Registered Environmental Technician).

Events We offer a range of events all over the UK on a variety of water sector topics. These events are a combination of technical visits, conferences, lunch and learns and social events, all presenting an opportunity to meet and network with top people from inside and outside the water sector. These events are often free or offer a discounted rate to members.

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Mentoring Our Mentoring Programme aims to unlock potential, support career goals and develop talent in the water industry. Mentors and mentees benefit both personally and professionally from this involvement and it is a great way of developing links with people and companies beyond your current employer.

Other benefits • An online CPD platform for planning and recording career development • A quarterly Magazine to keep up to date with water sector and Institute news as well as case studies and features on topical issues • Opportunities to enter a range of water sector-specific awards • Our brand new Institute of Water Journal, launched in the Spring of 2017 and published twice a year.

Robin’s career in the water industry began in 1992 when he started a PhD at the University of Birmingham researching the impact of ozone treatment on algalladen water and downstream water treatment processes. The PhD was sponsored by Anglian Water and, at the end of his studies, Robin was offered a 1 month contract by their Innovation team looking at the biology of activated carbon adsorbers. Over 20 years later, Robin’s scientific career at Anglian Water has taken him through the research and development, regulatory and operational teams, and Robin is currently Head of Water Quality, responsible for process science, public health liaison, water quality risk management along with water quality policy, strategy and regulation within the Water Services directorate. Robin’s role on the Institute of Water Board is to champion the professional development of scientists across the industry, particularly focused on developing Chartered Scientist and associated qualifications, working closely with the Science Council. Robin also chairs the Institute’s Membership and Standards Committee, and is the Board Diversity Champion.

Ian Barker CEnv Vice President Environment, Institute of Water Managing Director, Water Policy International Ian Barker is Water Policy International Ltd’s founder and Managing Director. With over 35 years’ experience in the water sector he identified the need for an independent consultancy able to cover the spectrum from policy formulation through to practical, integrated water management solutions and for an independent, authoritative voice on water policy and strategy. Ian has worked

within the water industry since before privatisation in 1989, when he opted for a career with the environmental regulator, rather than with one of the privatised companies. Since then, in a range of senior national roles at the Environment Agency, he aimed to ensure that the water companies (and others) could deliver environmental protection and improvement, whilst still reconciling their wider responsibilities. Ian is a Visiting Professor at the University of Exeter’s Centre for Water Systems, and is an Expert Advisor to the OECD on water governance, regulation and management.

Sam Phillips

CEng Vice President Engineering, Institute of Water Sam is a graduate of Queen’s University Belfast. In 1981 he joined Ferguson McIlveen LLP, Consulting Engineers and worked mainly on water engineering projects, becoming an Associate in the firm in 1988 and a Partner in 1992. He became a Director with Scott Wilson when it acquired Ferguson McIlveen in 2006 and when URS acquired Scott Wilson in 2010 he became Director responsible for Water & Infrastructure Engineering. Sam has over 30 years’ experience as a consulting engineer and has worked on a wide variety of projects in UK, Ireland, Africa and the Russian Far East. He is married and has one daughter. Sam is now retired and in addition to his work for the Institute of Water, is a Board member of the North West Zambia Development Trust and a passionate advocate for its work.

Marcus Rink CSci Chief Inspector, Drinking Water Inspectorate Marcus Rink was appointed as the Chief Inspector of Drinking Water in August 2015 after thirteen years with the Drinking Water Inspectorate at all levels. As Chief

Inspector he provides independent scrutiny of the water industry ensuring the safety and quality of water and public confidence through a robust regulatory framework. His role encompasses a range of statutory and nonstatutory functions, discharging the duties of the Secretary of State and the Welsh Government to ensure companies meet their regulatory requirements and Local Authorities take action in respect of private supplies. His career spans over 30 years with the Health Authority, ADAS, Public Analysts, Analytical Laboratories and the DWI providing a diverse insight into management, regulation, enforcement, health and the technical aspects of drinking water. Marcus is a member of the EU expert group advising on the Drinking Water Directive, the advisory EU microbiology expert group and the Chair of the Standing Committee of Analysts who produce independent methodology for water and environmental laboratories.

Lynn Cooper CPFA, CEnv Chief Executive, Institute of Water Lynn left her native Glasgow in 1983 with an Accountancy degree and qualified as an accountant with Sunderland and South Shields Water Company in 1987. She remained with the company when it became North East Water then Northumbrian Water until January 1997 when she moved to the Institute of Water as General Secretary. She was appointed as Chief Executive and a Board Member in December 2007. Lynn is a Founding Director of the Society for the Environment, where she served as Treasurer for eight years, and is a Chartered Environmentalist. In her spare time Lynn coaches middle to long distance runners and enjoys helping people to be the best they can.

Find out more at

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Building on our engineering heritage to shape the future of the water industry.


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Institute of Water 4 Carlton Court Team Valley Gateshead NE11 0AZ Tel: 0191 422 0088 @instwater 52 |

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