M A I N   N E W S

Dead animals, slush in treated water tanks
Ruchika M. Khanna
Tribune News Service

A Mumbai based tank cleaning service provider, Tanclean, which has been assigned the job of cleaning treated water supply tanks in Haryana, Delhi, Maharashtra and Karnataka, besides the tanks of Indian Railways, has found extreme levels of pollutants in the water tanks of the local municipal bodies and public health departments. In December, the company had extracted about 20 truck-loads of slush from the main water tank of Gurgaon, when it was cleaned after a period of 12 years. A crane was hired to remove the sludge over a period of eight days.

Besides dead rodents and birds, several feet high layers of bleaching powder (mixed in water tanks as a cleansing agent), were found in the tanks, adding to the list of existing pollutants. In most towns of Haryana, at least two feet high layers of bleaching powder were found in the water tanks, while in some towns of Maharashtra and Karnataka, over three feet high layers of bleaching powder were found in water tanks. High incidence of microbial pollutants like E Coli and various bacteria, besides moth and fungus, were also found in the water supply. This probably explains the high incidence of water borne diseases like cholera, hepatitis, typhoid and jaundice in the country.

Most of these tanks have not been cleaned by the authorities for years. This explains why the water supplied to our homes through these ‘unclean’ water tanks has high levels of contamination. As against 10 cfu per sq. cm. (colony forming units per square centimetre) of recommended level of contamination in polluted water, the minimum level of contamination was found in Nagpur (1440 cfu per sq. cm). “The total permissible dissolved solids, too, were found to be much higher than the permissible limit of 100 ppm (parts per million),” said Ketan Suresh Rane, Training Manager with Tanclean.

He said that lack of awareness on providing safe drinking water and methods employed for cleaning water storage tanks was a main reason for these tanks not having been cleaned for years. “Most of the tanks are cleaned by labourers hired by the public health authorities, who themselves act as carriers of microbial pollutants,” he added.

Manish Dubey, another company official, said the pollutants enter the water tanks either through the corroded and ruptured water supply pipelines or when the water tanks are left uncovered. “We clean the water tanks by first mechanised dewatering it, vacuum cleaning the tank and then remove the sludge. An anti-bacterial spray will be made in the tanks, before its high pressure cleaning. In the end, the inside of the tank is treated with specially developed ultra violet radiator to remove any suspended or floating bacteria,” he said, adding that after the treatment of water tanks, the level of contamination falls down to 4 cfu per sq. cm.