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Alternatively a latrine pan without water seal, accompanied by a vent pipe of minimum 100 mm diameter can be provided. In such a case, the vent pipe should reach above the roof level and the upper end of pipe should be covered by wire gause or net to prevent passage of vectors like flies and mosquitoes. This pipe will provide ventilation as envisaged in V.I.P. toilets.

13. Possibility of ground water contamination Possibility of microbial contamination of ground water obtained from tube wells must be considered. The leachet from borehole latrine will pass vertically and laterally through sand layer for adequate distance for attenuation of this contamination. In tube wells as well as dug wells microbial contamination was noticed where multiple latrines were present within a distance of few feet from the well. It will be advisable to keep a distance of about 50ft between wells and nearest latrine, to allow for attenuation of the contamination. As far as chemical contamination from on site sanitation is concerned nitrate contamination is the most important. As per WHO prescribed standards, in potable ground water, the nitrate levels should not exceed 50mg/Lt and nitrites at 3mg/Lt. High nitrate levels give rise to methaemaglobinaemia. Further, once the nitrate levels increase, remedial measures are not possible. It has to be noted that nitrates go on increasing in aquifer very gradually. It is a continuous slow process going on over the years. Therefore, chemical contamination of ground water needs to be monitored rigorously. In case of Dhamaka toilet, the bore reaches sand layer which is a part of aquifer as indicated in geohydrological maps. Hence, these nitrates are ultimately reaching the aquifer. From the 5 villages visited by us, from two villages, namely 3Y and 3G, nitrate trends from 2001 to 2007 were available. In 3Y nitrates were 4mg/Lt in 2001 against 10mg/Lt in 2007. In village 3G nitrates were 35mg/Lt in 2001 as against 45mg/Lt in 2007. This indicates a definite trend towards rise in nitrates levels. In few more years this might reach unacceptable level. Such data from remaining three villages was not available.


Dhamaka latrines in Rajasthan, India.  
Dhamaka latrines in Rajasthan, India.  

Study about appropriateness of design, possibility of conversion to sanitary latrine and extent of groundwater pollution caused Dhamaka lat...