Faulty pipelines leak 15 crore litres of sewage daily into Adyar and other city rivers
Between 15 and 18 crore litres of untreated sewage are leaking daily from Chennai's faulty, decades-old underground pipelines into stormwater drains and flowing directly into the Adyar River, Cooum River, and Buckingham Canal. Government data from the Municipal Administration and Water Supply (MAWS) department revealed that this massive volume of pumped sewage is failing to reach sewage treatment plants (STPs) due to extensive cracks in the city's aging transit network.
According to a MAWS report submitted to the National Green Tribunal (NGT), Chennai has an installed capacity to treat close to 1,000 million litres of sewage per day (MLD). While pumping stations pump approximately 835 MLD of sewage, Metro Water data shows that only around 650 to 680 MLD actually reaches the STPs.
The remaining 150 to 180 MLD of sewage leaks out of damaged underground pumping mains before reaching the plants. Additionally, several areas in Ambattur and south Chennai that lack connections to the underground sewage system continue to discharge sewage directly into stormwater drains and floodwater canals.
Metro Water sources stated that the underground pumping mains in several parts of the city were laid decades ago. These old pipelines have become damaged over the years, allowing sewage to enter stormwater drains through cracks.
The Kodungaiyur STP is currently the worst affected facility. Metro Water data shows that only about 50 percent of the sewage pumped to this plant is actually received. For instance, on July 6, the Kodungaiyur STP received only 179 million litres of sewage, despite a total of 324 million litres being pumped toward it.
To address the crisis, Chennai Metro Water is planning to adopt trenchless technology to seal leaks and fix damages in the underground sewer lines. This method would replace conventional, disruptive road-digging practices.
Under the proposed trenchless method, a flexible resin tube is inserted into the damaged pipelines and cured using hot water to form a new layer inside the existing pipe. An official stated that this technology would allow Metro Water to repair about 500 metres of underground sewer lines every day without digging up roads, extending the life of the pipelines by 40 years. The proposal is currently awaiting approval from the Metro Water board.
Previously, during the AIADMK regime, Metro Water had sent a Rs 10,200 crore proposal to repair the city's entire underground sewage system. However, the proposal was shelved after the DMK government took power.
