such cases are common in kolkata as many households prefer high reservoirs due to waterlogging during the rainy season the report said water supply pipes should have a life of 70100 years deb said kolkata domestic consumers are the principal contaminators of drinking water in kolkata in monetary terms the imlication is even more alarming in such a situation if the reservoir is located at a higher level than the water supply mains the water returns to the supply line from the reservoir due to the natural gravity kolkatas centuryold water supply system desperately needs to be rehauled deb led a team of experts of weston international metcalfe eddy philadelphia suburban water supply company and local firm stup consultants in the yearlong study which cost 13 million this means that rs 12 crore is spent every day just to produce this purified water of which rs 42 lakh literally goes down the drain leakage occurs due to the use of unlined cast iron pipes the world banksponsored study team examined the problem areas in all 141 wards under the calcutta municipal corporation and suggested measures for improvement one of the major initiatives in this area is to change the existing pipes water produced in palta and garden reach is of good quality but faults in the distribution system cause contamination on the way arun deb vicepresident of usbased firm weston international said most citizens do not know how to keep their reservoirs clean deb said at present 180 million gallons mgd of purified water is produced at palta every day while the figure for garden reach is 60 mgd this fact was revealed in a recent study on kolkatas water supply system sponsored by the world bank one of the principal tasks of the study was to identify such leaks these were discontinued in the usa in the 1930s deb said the total project cost has been estimated at 264 million we have put forward a proposal by which the losses in distribution can be reduced to 25 per cent in the next five years deb said the survey clearly shows that more than 35 per cent of the daily water that is produced at the water works in palta and garden reach is lost due to leaks in the distribution system the cost of purifying water is rs 10 per kilolitre of water the study showed that even pipes laid as late as in 1985 have leakages contamination occurs due to poor maintenance of reservoirs at homes and the problem worsens because there is no check valve to prevent water supplied to the houses from returning to the system