Tests by the Tamil Nadu Pollution Control Board show the presence of coliform bacteria in samples of untreated water drawn from Porur, Red Hills, Poondi and Veeranam waterbodies, which serve as sources of supply to the city.
TNPCB has been monitoring the water quality under the Central Pollution Control Board's Monitoring of International Aquatic Resources System programme from February this year.
The samples are taken every month and tested at the TNPCB's laboratories for various parameters, including the level of pH, nitrate, chloride, total hardness, calcium hardness, sulphate and magnesium.
“Coliform contamination in the surface water is a common phenomenon due to unhygienic anthropogenic activities before chlorination,” sources in the board said. Chennai Metrowater supplies a total of 710 million litres a day to the city, of which 695 mld is through pipes. Engineers of the Quality Monitoring Wing of Metrowater said: “Water is supplied only after treatment and the treated water does not have any coliforms. It is tested before being supplied to the residents.”
Residents of Red Hills said the tank's bund was used as an open toilet. “There are no security personnel to guard the entire perimeter. There are many residential areas surrounding the tank and people use the water for purposes other than drinking,” a resident said.
Sources in the Water Resources Department, said that no effluents or sewage disposal is allowed in these waterbodies.
