CHENNAI: Sewage and faecal material contamination in the Tamil Nadu waterbodies could be very high, indicate a report by the Central Pollution Control Board (CPCB). The report, the study for which was undertaken in 2019, was released in December 2020.
Among the reservoirs in the State, the Poondi reservoir contains 9,200 coliform bacteria (measured as Most Probable Number or MPN) per 100 ML of water, which is at least four times the levels in other waterbodies such as the ones in Red Hills (2,790), Porur (2,800), and Udhagamangalam (2,200), shows the report. The presence of coliform bacteria indicates the entry of sewage and faecal matter into the waterbodies.
While total coliform levels remain high before treatment in all the catchment reservoirs, by the CPCB standards, the Poondi reservoir remains the worst. Professor S Janakarajan, an expert in water management and disaster-risk reduction, said, “It’s a very bad sign. The inlet points must have a filtering mechanism to control coliform levels and water must be treated through a bio-filtering process. This can also save a lot of energy when this water is subsequently treated through conventional methods.”
In addition to a 24X7 filtering, the reservoirs must be safeguarded from public access, and only the public can do that, he added. “The reservoirs are generally open to all, so the possible open-defecation on pathways to the reservoir needs to be addressed,” he added.
Also, TNIE accessed several RTI replies from the Municipal Administration and Water Supply Department that admitted to the presence of high total coliform levels in waterbodies. The replies said coliform bacteria contaminate groundwater and harms animals and humans. Sources in Chennai Metro Water said total coliform levels must not exceed 230 MPM per 100 ML but admitted that pollution levels were high at water sources.
“The final product that people get, however, is treated water, wherein coliform levels are zero,” official sources told TNIE. A 2021 report by Metro Water showed coliform levels in drinking water provided to the public as zero and the water quality adhering to BIS standards.
Waterbody conservation activists, however, call for immediate intervention to protect drinking water sources from pollution. “Sewage entry into freshwater sources cannot be permitted when we have adequate data to prove contamination. The entry sources need to be identified and sealed,” said city-based activist Dhayanand Krishnan. He urged for government intervention at the earliest.
Heavy rains likely in 25 dists
Chennai: The regional meterological centre on Tuesday predicted heavy rains in 25 districts till October 22. According to the weather bulletin, scattered heavy-to-isolated very heavy rain is likely over South Tamil Nadu (Ramanathapuram, Tirunelveli, Tenkasi, Thoothukudi, Theni, Kanniyakumari, Sivaganga, Virudhunagar, Dindigul, Madurai), interior Tamil Nadu (Vellore, Tiruvannamalai, Krishnagiri, Dharmapuri, Salem, Namakkal, Erode, Karur, Tiruchirapalli, Ariyalur, Perambalur) and Western Ghat districts (Nilgiris, Tiruppur, Coimbatore, Theni). In Chennai, the sky is likely to be remain partly cloudy with light rain likely.