Development of a Drinking Water Distribution Network by Utilizing Penida Springs in Nusa Penida Dist

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Development of a Drinking Water Distribution Network by Utilizing Penida Springs in Nusa Penida District Klungkung Regency Evan Suputra1, I Gusti Ngurah Kerta Arsana2, Silvia Gabrina Tonyes3, Ni Nyoman Pujianiki4, I Gusti Agung Adnyana Putera5, I Putu Gustave Suryantara Pariartha6 1PG Student, Civil Engineering Study Program, Udayana University, Badung, Bali, Indonesia 2Asst. Professor, Environmental Engineering Study Program, Udayana University, Badung, Bali, Indonesia

3Asst. Professor, Doctor of Engineering Science Study Program, Udayana University, Badung, Bali, Indonesia 4Professor, Magister of Civil Engineering Study Program, Udayana University, Badung, Bali, Indonesia 5Asst. Professor, Civil Engineering Study Program, Udayana University, Badung, Bali, Indonesia 6Asst. Professor, Civil Engineering Study Program, Udayana University, Badung, Bali, Indonesia

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Abstract - Nusa Penida District is experiencing an

meet human needs. Water distribution systems (WDS) are designed to provide water in sufficient quantities and at the required quality without compromising future capacity and standards. The issues of drought, climate variability, pollution, climate change, and urban population development have led to the emergence of various and interconnected water delivery systems [1]. The accomplishment of the Sustainable Development Goals (SDGs) is at danger due to inadequate water, which also posessa increased hazards to human health, food production, energy generation, economic development, and poverty reduction. The government must guarantee that the community has access to safe and reasonably priced clean drinking water in order to meet SDG number 6, which focuses on clean water and adequate sanitation [2].

increasing need for clean water along with population growth and tourism, but the drinking water distribution system is still highly dependent on the Guyangan spring which requires many pumps and electrical energy. This study aims to plan the development of a drinking water distribution network by utilizing the potential of the Penida spring and interconnecting it with the existing system in Guyangan to improve technical and economic efficiency. The methods used include an analysis of water needs of 113.34 liters/second (equivalent to 3,572,342 m³ per year), network planning using ARCGIS and hydraulic simulation with QEPANET, and an evaluation of economic feasibility based on NPV, IRR, and BCR indicators. The results show that the interconnection network is able to distribute water from the Penida spring to 11 villages in the central and western regions of Nusa Penida, reducing the operational load of pumps, and increasing the coverage of water services. The economic analysis was conducted on four scenarios related to water prices and subsidies on investment. The water price per cubic meter was obtained at Rp. 3000 which is determined by considering the initial investment costs, annual operational costs, project duration, and interest rates (discount rates). With positive NPV results, IRR approaching or exceeding the interest rate of 8%, and BCR > 1, this indicates that the SPAM network development project is feasible. Therefore, the development of this gravity-based SPAM network interconnection system can be an efficient and sustainable solution for clean water supply in Nusa Penida.

The management and distribution of water to billions of people in need is a crisis that contributes to the global water crisis in addition to water shortages. There are much less water resources available globally, necessitating focused efforts to manage water effectively and efficiently. The use of sporadic supplies, typically determined by necessity rather than design, is one of the most popular strategies for reducing water demand [3]. The sustainable aspect of water supply includes three main objectives: economic, social, and environmental factors related to the functional use of water, as well as the management of clean water and wastewater.

Water is mostly used for domestic purposes, such as drinking, cooking, bathing, and cleaning; secondly, for industrial purposes in energy production and manufacturing; and thirdly, for agricultural purposes in irrigation [4].

Key Words: drinking water system supply, Penida spring, network interconnection, EPANET, economic feasibility

The exploitation of springs on Nusa Penida Island necessitates complicated infrastructure and significant funding, so the operational system is carried out collaboratively by the Central Government, the Bali Provincial Government, and the Klungkung Regency Government. The Central Government, through the Bali Penida River Basin Center, the Bali Provincial Government, through the Regional Technical Implementation Unit for Drinking Water Management, and the Klungkung Regency

1.INTRODUCTION The most basic necessity for all living things is water.

Climate change, development activity, and population growth are the main causes of scarcity. High rates of population increase and climate change have decreased the amount, quality, accessibility, and availability of water to

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Penida Spring (potential 181.7 l/s), raw water production from Guyangan Spring (potential +172.07 l/s) is only 20 lt/second. Raw water reserves from Penida Spring and Guyangan Spring that have not been used remain significant (306.77 l/s). Penida Spring is located near Crystal Bay Beach, but Guyangan Spring is situated on an extremely steep cliff 220 meters below ground level [13].

Government, have appointed the Local Water Company, currently known as "Perumda Air Minum Panca Mahottama," as the operator. This management is carried out in a single system, beginning with the embankment of springs as raw water, routing water from the intake tank to the reservoir, and delivering drinking water to clients. This system is known as the Drinking Water Supply System (DWSS) [5]. A water distribution system is an integrated network of water sources, pipes, and hydraulic control modules such as valves, regulator pumps, and reservoirs that transport water for final usage under standard pressure [6, 7]. This technique is accomplished by operating pumps, main and service pipes, storage tanks or reservoirs, and associated equipment under pressure in a closed system [8].

Nusa Penida's water supply system currently relies on two main sources: the Penida spring and the Guyangan spring.

Both sources are critical to addressing the community's and other stakeholders' clean water needs. According to data from the Klungkung Regional Water Company and the DWSS development master plan, the Guyangan spring is currently equipped with seven reservoirs and five to six pumps that distribute water to various distribution zones in Nusa Penida's western and central areas [14].

The DWSS development aims to build, expand, and/or improve physical (technical) and non-physical systems (institutional, management, financial, community participation, and legal) in a complete unit to implement the provision of drinking water to the community in a better condition in accordance with Indonesian Government Regulation Number 16 of 2005 [9]. Given Nusa Penida Island's limestone mountainous topography, transferring drinking water from coastal sources to residential areas necessitates several pumping operations. For instance, the Guyangan DWSS system necessitates five pumping processes. The use of several pumps in the distribution system not only raises power prices, but also increases the danger of operational disruptions caused by mechanical breakdowns, as well as the carbon footprint of energy use.

Therefore, a strategic and technological strategy is needed to create a DWSS network interconnection system to distribute a portion of the supply from the Penida springs to the Guyangan area, thereby reducing pumping load and enhancing overall system efficiency [10].

On the other side, the Penida springs, which have significant discharge potential, only have two reservoirs and have yet to be completely utilized for regional distribution. This shows an imbalance in resource usage between the two systems, affecting technical and economic efficiency, particularly the Guyangan system's high pumping costs [15].

1.2 Study Area This investigation was carried out in Nusa Penida District, Klungkung Regency, Bali Province, Indonesia. Nusa Penida is a district in Klungkung Regency, Bali Province, with an area of 202,838 km2 and a population of 63,468. Nusa Penida District has three islands: Nusa Penida Island, which has an area of 191,462 km2, Nusa Lembongan Island (8,688 km 2), and Nusa Ceningan Island (2,688 km2). Nusa Penida Island is located in the coordinate SL 08o40'18.9"- 08o50'10.8" and ES 115o26'47.6"-115o37'41.8" [16].

In light of this, the purpose of this study is to assess the technical feasibility and operational benefits of connecting the Penida spring reservoirs to numerous reservoirs in the Guyangan system in order to improve the efficiency of clean water distribution in the Nusa Penida region.

1.1 Drinking Water Supply System in Nusa Penida Fig -1: Study area

Clean water is a basic human requirement that must be fulfilled in a sustainable manner. The supply and distribution of clean water pose significant issues, particularly in island locations such as Nusa Penida, Klungkung Regency, Bali. As the island experiences substantial visitor growth, strain on the region's DWSS grows [11].

2. METHODS This study is based on Indonesian and international national norms and/or criteria. Water demand planning factors include domestic and non-domestic water supply standards, water loss, and changes in demand [17]. Nusa Penida District is classified as a small city, hence the following home water consumption is planned: 130 liters/person/day, unit consumption (HU) of 30 liters/person/day, non-domestic water consumption of 600 liters/unit/day, 20% water loss, maximum day factor of 1.15%, peak hour factor of 1.75%, and 90% projected service coverage. Meanwhile, the non-

As a karst island, Nusa Penida Island, which does not have a year-round river, has several springs, particularly on the southern slopes, including Penida Spring (Sakti), Guyangan Spring, Seganing Spring, Tembeling Spring, Tabuanan Spring, Antapan Spring, Wates Spring, Angkel Spring, and Toya Pakeh Spring [12]. Two springs have been used in the form of a DWSS: Penida Spring (potential: 181.7 l/s) and Guyangan Spring (potential: 172.07 l/s). When considering the vast potential of springs that have yet to be fully used, such as

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domestic water demand is estimated to be 15-30%.

Furthermore, the transmission and distribution pipeline planning criteria are based on Indonesian Minister of Public Works and Public Housing Regulation No. 27/PRT/M/2016, which includes a flow velocity of 0.6 m/s, a minimum water pressure of 1 atm, and a maximum pressure determined by the pipe specifications.

Where SHP is shaft horse power (watt), Pmot is the power of the electric motor driving the pump (watts), p is the total efficiency of the pump (%), and mot is the efficiency of the electric motor (%).

Economic analysis is the process of comparing costs and advantages to determine whether a business will be profitable over its existence. When we try to optimize, we either reduce resource consumption and costs or increase profit and system performance. In reality, money, time, and resources are typically limited; so, operations require optimization [20]. Net Present Value (NPV) is an economic feasibility research method that takes into account the time value of money to determine a project's net benefits. If the NPV is positive, the project is deemed viable because it is expected to generate net profits. Conversely, if the NPV is negative, the project is not practicable because the overall costs outweigh the benefits [21].

Furthermore, population growth forecasts are initially computed using three methods: arithmetic, geometric, and least squares [18].

Arithmetic Method:

Pn = Po(1+r.n)

(1)

Geometric Method:

Pn = Po(1+r)n

(2)

Least Square Method: Pn = a+b(n)

(3)

Where Pn is the population in year n, Po is the population in the first year, r is the population growth rate (%), n is the projection year, an is a constant, and b is the linear regression coefficient. The standard deviation is calculated after applying the three procedures described above. After calculating with these three approaches, the standard deviation for each method is calculated. The approach with the smallest standard deviation is used to calculate population projections. Based on the population projection data, the expected water demand is computed for both household and non-domestic usage using the study area criteria.

(6) Where Bt is the benefit in year t, Ct is the operating cost in year t, C0 is the initial investment cost, r is the discount rate, and t is year t.

Furthermore, the Benefit-Cost Ratio (BCR) is an economic evaluation tool that compares the present value of a project's total benefits to its total costs. The BCR shows how much benefit is achieved for every unit of cost incurred. If the BCR exceeds one, the project is regarded viable because the benefits outweigh the costs. Conversely, if the BCR is less than one, the project is not feasible since the costs outweigh the benefits.

The pipe diameter is determined by the amount of water discharged and may be computed using the continuity equation: Q = A.v = ¼d2.v

(4)

where, Q is the flow rate (m3/s), A is the pipe cross-sectional area (m2), d is the diameter (m), and v is the flow velocity (m/s).

(7)

A pump unit moves water from a lower tank or reservoir to a higher reservoir. In pump design and selection, the pump discharge (Q) and head (Hp) must be determined. Head is defined as the specific energy per unit weight of fluid. Pump head is made up of potential energy, flow pressure energy, kinetic energy, and energy losses from the pipe system. As a result, there are four types of heads: static, pressure, velocity, and friction [19].

Hp = (z2-z1) + (p2-p1)/(g) + (v22-v12)/(2g) + Hf

The Internal Rate of Return (IRR) is then used to assess a project's efficiency and profitability. The higher the IRR, the better the project's profitability. The IRR assists decisionmakers in determining the feasibility of a project in relation to a benchmark interest rate or the minimum expected rate of return (also known as the discount rate). If the IRR is more than the benchmark interest rate, the project is regarded financially viable because the returns exceed the cost of capital. In contrast, a smaller IRR indicates that the project is unprofitable.

(5)

Where Hp is the total pump head (m), z is the elevation (m), p is the pressure (N/m2), v is the velocity (m/s),  is the fluid density (kg/m3), g is the gravitational acceleration (m/s2), and Hf is the head loss due to friction (m).

The method of connecting pipes determines the configuration of a water distribution system. The most popular fundamental configurations are serial, branch, loop, and combination [22]. A serial configuration is basic, with no loops or branching. A serial construction is constrained by its high construction and maintenance expenses [23]. A branching configuration consists of two or more serial configurations. The primary restrictions include sporadic water demand, potential system contamination, low

Next, the quantity of pump power needed is: SHP = (.g.Q.Hp)/p

(6)

Pmot = SHP/mot

(7)

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reliability, and silt accumulation [24]. A loop arrangement consists of demand points (nodes) that can accept water from more than one source. This technology is mostly utilized in urban/industrial regions to ensure appropriate distribution and high dependability [25]. This study makes use of a hybrid arrangement. The circular layout is the system's major feature, with supply provided at the area's periphery via a number of branches.

Table -1: RDWC Nusa Penida Service Coverage

No

The process that will be used for the thesis is depicted in Fig2.

3. RESULTS AND DISCUSSION

To supply the water needs of the Nusa Penida District community, the Nusa Penida RDWC uses two primary springs: Penida Spring and Guyangan Spring. As stated in Table 1, the current clean water coverage of RDWC Nusa Penida is 59.44%. The other two villages on Nusa Ceningan and Nusa Lembongan, called Jungutbatu and Lembongan Villages, get their water from seawater via Sea Water Reverse Osmosis (SWRO).

Impact Factor value: 8.315

Populati on (Person)

Residents served (Person)

Perce ntage (%)

1

Suana

291

4,544

1,144

25.17

2

Batununggul

999

6,565

3,926

59.80

3

Kutampi Kaler

831

3,488

3,266

93.63

4

Ped

1,181

6,612

4,641

70.19

5

Toyapakeh

141

675

554

82.07

6

Sakti

936

5,020

3,678

73.26

7

Klumpu

786

4,355

3,089

70.93

8

Batumadeg

573

2,645

2,252

85.14

9

Bungamekar

630

3,246

2,475

76.24

10

Batukandik

949

4,610

3,730

80.91

11

Kutampi

672

3,604

2,641

73.28

12

Sekartaji

107

1,650

421

25.51

13

Pejukutan

-

3,636

-

0

14

Tanglad

-

2,879

-

0

Total

8,096

53,529

31,817

59.44

The Guyangan Raw Water Supply System, on the other hand, draws water from the Guyangan Spring in Batukandik Village.

Guyangan Spring is a spring that emerges from a rocky cliff near the Segara Kidul Temple. The Guyangan Spring supplies eight villages, including Bungamekar, Batumadeg, Batukandik, Klumpu, Kutampi, Pejukutan, Sekartaji, and Tanglad. Tanglad and Pejukutan, on the other hand, continue to be cut off from water from the Guyangan Spring. This is because the flow rate to the Guyangan R-6 remains extremely low, at 3 liters per second. Furthermore, the Nusa Penida Water Company is restructuring the distribution pipes in the

3.1 Existing Overview of Nusa Penida DWSS

|

Custo mer (HC)

The Penida Raw Water Supply System draws from the Penida Spring in Sakti Village, which emerges near Crystal Bay Beach on Nusa Penida. The Penida Spring serves six villages; Sakti, Toyapakeh, Ped, Kutampi Kaler, Batununggul, and Suana. The Penida SPAB transmission flow system employs a combination of pumps and gravity. Water in the inundation area is channeled to tank 1 located north of the reservoir via a 0.8 m diameter concrete pipe with a length of 190 m, and then pumped to reservoir 1 (round reservoir) with a capacity of 1500 m3. Water is gravity-fed from the circular reservoir to Sakti Village, then to reservoir 2 with a capacity of 200 m3, where it is dispersed to Toyapakeh Village, Ped Village, Kutampi Kaler Village, Batununggul Village, and Suana Village. Gravity is used throughout the entire distribution system. Under current conditions, the Penida spring may produce a discharge of 70 liters per second.

Fig -2: Methodology

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two villages so that they may be used to distribute water this year.

A predicted water demand estimate is required on Nusa Penida Island, which includes population, household, nondomestic, total water demand, water loss, average water demand, maximum water demand, and peak hour demand.

Clean water use in the Nusa Penida area is set at 120 gallons per person per day. The projected water demands are shown in Table-3.

The population projections are calculated using three approaches. The population projection methods employed include mathematical, geometric, and least squares. The population data used to construct the forecasts spans the last four years, from 2021 to 2024. The smallest deviation will determine whether strategy is utilized. To demonstrate the procedure to be utilized, this computation will be performed on Sakti Village. The calculation is carried out using each of the three approaches discussed above.

Table -3: Projected water demands on Nusa Penida island No

Description

Unit

Year 2039

person

75,182

%

80

person

60,145

liters/person /day

120

liters/day

7,217,441

20% of Domestic Demand

liters/day

1,443,488

Total Water Demand

liters/day

8,660,929

liters/second

100.24

After performing calculations using the three methods, the standard deviation of the arithmetic method was 47, the geometric method was 55, and the least squares method was 74. Based on the calculation results, the lowest standard deviation was obtained from the arithmetic method.

Therefore, the method used to calculate population projections uses the arithmetic method. The results of the population projection calculation for the next 15 years using the arithmetic method can be seen in the Table-2.

A

Population

1

Total Population

2

Service Level

3

Served Population

B

Domestic Demand

1

House connection

Table -2: Population Projection of Nusa Penida District

2

Home Water Connection Requirements

C

Non-Domestic Demand

No

Village

Population (person) in Year: 2024

2025

2029

2034

2039

1

Suana

4.783

4.830

5.016

5.250

5.483

2

Batunungg ul

3.114

3.148

3.285

3.455

3.626

3

Kutampi Kaler

5.089

5.157

5.427

5.765

6.103

4

Ped

5.721

5.793

6.081

6.442

6.802

5

Toyapakeh

2.099

2.138

2.296

2.492

2.689

6

Sakti

2.905

2.939

3.074

3.242

3.411

7

Klumpu

4.351

4.394

4.565

4.779

8

Batumade g

5.878

5.925

6.111

6.345

9

Bungamek ar

3.703

3.731

3.844

3.985

4.126

10

Batukandi k

5.437

5.525

5.876

6.316

6.755

11

Kutampi

832

843

886

941

995

12

Sekartaji

5.284

5.324

5.484

5.684

5.885

13

Pejukutan

4.033

4.062

4.177

4.320

4.464

14

Tanglad

3.665

3.699

3.837

4.010

4.182

15

Kutampi Kaler

3.686

3.715

3.831

3.975

4.120

16

Bunga Mekar

4.000

4.065

4.323

4.647

4.970

Total

63.906

64.580

65.287

68.114

75.182

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D

E

Water Loss

1

Percentage of water loss

2

%

20

Total water loss

liters/second

20.05

F

Average Water Requirements

liters/second

120.29

4.992

G

Maximum Water Requirements

6.578

1

Coefficient Factor

-

2

Maximum Water Requirements

liters/second

H

Peak Water Requirements

1

Coefficient Factor

2

Peak Water Requirements

Impact Factor value: 8.315

1.2

-

144.35

2.0

liters/second

240.58

3.2 Drinking Water Supply System in Nusa Penida The Penida spring water network serves six villages: Sakti, Toyapakeh, Ped, Kutampi Kaler, Batununggul, and Suana, as shown in Fig-3. The Guyangan spring water network feeds eight villages: Bungamekar, Batumadeg, Batukandik, Klumpu, Kutampi, Pejukutan, Sekartaji, and Tanglad, as shown in Figure 4. Based on established service areas, the RDWC has yet to fully serve two villages, Tanglad and Pejukutan,

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indicating inadequate service in these locations. This is seen in the inefficient distribution of service regions, where the use of Penida spring water remains suboptimal when compared to Guyangan spring water.

certain pressure as well as to assist management if regulated by village zoning.

Fig-5: The Proposed Nusa Penida RDWC Network Scheme Fig-3: Penida Spring Service Area

With these adjustments, the Penida spring will service 13 villages: Sakti, Toya Pakeh, Ped, Kutampikaler, Suana, Batumadeg, Bunga Mekar, Klumpu, Pejungkutan, Sekartaji, and Tanglad Village. With this interconnection, each service village's water demands must be recalculated in order to produce appropriate outcomes based on the service area.

Table-4 shows the computation of water demands in the 13 villages, as well as the number of SRs, assuming that each SR serves 5 people.

Table -4: Water Demands of Penida Spring Service Area No

Tapping Point

Service Area (Village)

Water Demand (L/s)

1

Sakti

10.53

Fig-4: Guyangan Spring Service Area

2

Toyapakeh

11.30

The use of Penida's springs demands to be developed due to their easier access compared to Guyangan's. At Guyangan, several pumping stages are required to channel the water to the reservoir. These pumping stages require more electrical energy, which will impact the water bill charged by the local water company.

3

Ped

1.91

4

Batununggul

11.29

5

Kutampi Kaler

12.97

6

Suana

9.59

Kutampi

7.92

Klumpu

11.72

Pejungkutan

7.91

Bungamekar

9.54

Batumadeg

6.96

Sekartaji

5.16

Tanglad

6.55

7

Penida spring has a round reservoir with a capacity of 1,500 m3, which serves six villages: Sakti, Toyapakeh, Ped, Kutampi Kaler, Batununggul, and Suana. Meanwhile, Guyangan Spring uses seven reservoirs placed throughout the service region to meet water demands, although the typical distribution system use pumps. Penida spring can still help flow water to Guyangan reservoirs R-3, R-4, and R-6, which are now being pumped up to five stages. To satisfy the demands of R-3, R-4, and R-6 Guyangan, a pump system will be installed from R1 Penida to R-4 Guyangan, followed by pumps R-3 and R-6 using a gravity system. Gravity will deliver water to each village, and a reservoir will be built in each village to give a

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R2 Penida

R3 Guyangan

9 10 11 12 13

R4 Guyangan

R6 Guyangan Total

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Total Demand (L/s)

47.99

37.14

16.50

11.71 113.34

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The estimations are based on the maximal water demand.

The Penida spring water production capacity is currently 70 liters per second, and with a total demand of 113.34 liters per second, the water demand in the Penida service area will still be 43.34 liters per second in the planned year, as shown in Table-4.

maintenance costs are 3,491,910,488 IDR, for a period of 20 years, by assuming an initial water price of 3,000 IDR, according to the current RDWC water price. In order to determine the economic feasibility, the NPV, BCR, and IRR methods are conducted.

To calculate economic feasibility, variable data are: Cost: - Construction (IDR) 75,023,681,000 - M & O (IDR/year) 3,491,910,488 Benefit: - Water Price (IDR/m3) 3,000; 4,000; - Water Demands (liters/people/day) 130 - Water Demands (m3/year) 3,574,393 - Water loss 10% 3,216,954 - Benefit (IDR/year) 9,650,861,647 Interest Rate Level 8% Duration (year) 15

The Penida spring service region, which will have a 43.34 liters/second loss in the planned year, poses a challenge that necessitates transmission network optimization. This plan's optimization entails modifying the service area to use more appropriate spring sources based on each village's distance and elevation. The analysis results are summarized in Fig-6.

Then, the analysis is conducted for each scenario.

The first scenario yields an NPV of -20,615,228,959 and a BCR of 0.725%. Since NPV <0 and BCR <1, this investment is deemed unfeasible. Furthermore, the second scenario yields an NPV of 18,238,217,041 and a BCR of 1.099%. Since NPV >0 and BCR >1, this investment is deemed feasible. Then, the third scenario yields an NPV of 7,483,899,522 and a BCR of 1.504%. Since NPV >0 and BCR >1, this investment is also deemed feasible. Finally, the fourth scenario yields an NPV of 46,337,345,522 and a BCR of 2.28%. Since NPV >0 and BCR >1, this investment is also deemed feasible.

Fig-6: Optimization of the Penida’s Spring Service Area

3.2 Economic Feasibility Analysis To obtain a comprehensive overview of the economic feasibility of developing a Drinking Water Supply System (DWSS) utilizing Penida springs in Nusa Penida District, a four-scenario analysis was conducted. The first scenario calculated the total investment costs required to build a drinking water distribution system, without any third-party financing intervention. This scenario assumed a water selling price of IDR 3,000 per cubic meter. The second scenario still considered all investment cost components but assumed a water selling price of IDR 4,000 per cubic meter.

The third scenario simplifies the investment burden by reducing the cost of the reservoir and main piping, namely R1 Penida, R3 Guyangan, R4 Guyangan and R6 Guyanagn, as a simulation of conditions if there are funding assistance or subsidies from the government, but still maintains operational and maintenance costs with a water selling price in this scenario of 3,000 IDR per cubic meter. The fourth scenario uses the same initial investment costs as the third scenario but with a higher water selling price, namely 4,000 IDR per cubic meter.

For instance, calculation of Benefits and Costs results for the third scenario were obtained as in Table-5. Furthermore, the analysis of the four scenarios is summarized in Table-6.

Table-5: Calculation of Benefits and Costs for the first scenario

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Water Demand (m3/yr)

Benefit (IDR)

Cost (IDR)

Net Benefit (IDR)

Discount Factor (8%)

(n)

(WD)

(B)

(C)

(NB)

(i)

36,170,23 5,000

(36,170,2 35,000)

0

In conducting an economic feasibility analysis, it is necessary to calculate the investment value in this distribution, so a budget plan is made for costs and operational-maintenance cost every year. From the recapitulation, the investment value is 75,023,681,000 IDR, and the annual operational and

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Year to

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1

3,088,7 39

9,266,21 6,408

3,491,910 ,488

5,774,30 5,920

5,346,57 9,556

2

3,123,4 28

9,370,28 5,208

3,491,910 ,488

5,878,37 4,720

5,039,75 8,848

3

3,158,1 18

9,474,35 4,008

3,491,910 ,488

5,982,44 3,520

4,749,05 6,546

4

3,192,8 08

9,578,42 2,808

3,491,910 ,488

6,086,51 2,320

4,473,76 8,255

5

3,227,4 97

9,682,49 1,608

3,491,910 ,488

6,190,58 1,120

4,213,20 5,490

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6

3,262,1 87

9,786,56 0,408

3,491,910 ,488

6,294,64 9,920

3,966,69 7,191

7

3,296,8 76

9,890,62 9,208

3,491,910 ,488

6,398,71 8,720

3,733,59 0,915

8

3,331,5 66

9,994,69 8,008

3,491,910 ,488

6,502,78 7,520

3,513,25 3,760

9

3,366,2 56

10,098,7 66,808

3,491,910 ,488

6,606,85 6,320

3,305,07 3,050

10

3,400,9 45

10,202,8 35,608

3,491,910 ,488

6,710,92 5,120

3,108,45 6,815

11

3,435,6 35

10,306,9 04,408

3,491,910 ,488

6,814,99 3,920

2,922,83 4,079

12

3,470,3 24

10,410,9 73,208

3,491,910 ,488

6,919,06 2,720

2,747,65 5,003

13

3,505,0 14

10,515,0 42,008

3,491,910 ,488

7,023,13 1,520

2,582,39 0,885

14

3,539,7 04

10,619,1 10,808

3,491,910 ,488

7,127,20 0,320

2,426,53 4,043

15

3,574,3 93

10,723,1 79,608

3,491,910 ,488

7,231,26 9,120

2,279,59 7,606

149,920, 470,120

88,548,89 2,320

61,371,5 77,800

54,408,4 52,041

3. CONCLUSIONS 1. Based on the results of planning and projection of water needs, the number of household connections that can be served in Sakti Village is 1516 SR, Toya Pakeh Village 1627 SR, Ped Village 275 SR, Batununggul Village 1625 SR, Kutampi Kaler Village 1868 SR, Suana Village 1380 SR, Kutampi Village 1141 SR, Klumpu Village 1687 SR, Pejungkutan Village 1140 SR, Bunga Mekar Village 1374 SR, Batumadeg Village 1002 SR, Sekartaji Village 744 SR, Tanglad Village 943 SR 2. The development of the water distribution network is carried out from the Penida Spring which is pumped to R1-Penida with a pump head of 180, for the villages of Sakti, Toya Pakeh, Ped, Batununggul and Kutampi kaler distributed from R1-Penida to each Village Reservoir with a gravity system, then R1-Penida also interconnects R4-Guyangan with a pump head system of 200, where R4-Guyangan also distributes the Bungamekar Village Reservoir and Batu Madeg Village with a gravity system, then continues from R-4 Guyangan to R-3 Guyangan with a pump system using a pump head of 180, R3-Guyangan also distributes the Suana Village Reservoir, Kutampi Village, Klumpu Village, and Pejungkutan Village. Then from R3-Guyangan it is distributed to R-6 Guyangan with a gravity system, where R-6 distributes water to the Sekartaji and Tanglad Village Reservoirs.

3. The price of water per meter cubic is obtained at a price of 3,000 IDR which is determined by considering the initial investment costs, annual operational costs, project duration, and interest rate (discount rate). With a positive NPV result, the IRR approaches or exceeds the interest rate of 8%, and BCR > 1 indicates that this Drinking Water Supply System (DWSS) network development project is feasible.

Then, by using Eq. 6, 7 and 8, the following results are as in Table-6.

Table -6: Economic Analysis Results Scen ario

Water Price (IDR)

NPV (IDR)

BCR (%)

IRR

Decision

I

3,000

(20.615.228 .959)

3,34

0,73

Rejected

II

4,000

7.483.899.5 22

9,54

1,10

Accepted

III

3,000

18.238.217.

041

15,20

1,50

Accepted

IV

4,000

46.337.345.

522

24,91

2,28

Accepted

ACKNOWLEDGEMENT The authors would like to express their gratitude to the Post Graduated of Civil Engineering Study Program, Faculty of Engineering, Udayana University.

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Although there are three scenarios (II, III, IV) with economically feasible results, the selection of the best scenario is not only determined by the value of the feasibility indicator, but must also consider the community's ability to pay the water price. Technical and economic feasibility must be balanced with social aspects, so the scenario with a water price of IDR 3,000/m³ (scenario III) is a more realistic choice to be implemented because it still produces good feasibility indicators despite using a lower price and lighter investment.

Thus, scenario III can be considered the optimal choice, considering cost efficiency and community purchasing power.

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