Mumbai diverts all 20 sewage streams away from Powai Lake

The Brihanmumbai Municipal Corporation has completed work to intercept and divert all 20 identified sewage streams flowing directly into Powai Lake, ending the direct discharge of sewage into the lake.

Of the 20 streams, 18 sewage outfalls along Adi Shankaracharya Marg, also known as JVLR, have been connected to the existing sewer network leading to the Bhandup Sewage Treatment Plant, reported The Hindustan Times.

The remaining two streams at Peru Gate, on the northern edge of the lake, have been diverted to the Filterpada Sewage Treatment Plant.

The project involved laying 3,056 metres of new sewer lines. Work began in August 2025 and was completed in 13 months.

The intervention follows years of complaints from residents and environmental groups over sewage pollution and the growth of water hyacinth in the lake.

A committee appointed by the National Green Tribunal found in 2022 that around 10.9 million litres of untreated sewage was entering Powai Lake every day through 15 culverts. The NGT subsequently directed the BMC to stop the discharge.

The BMC’s assessment in 2025 put untreated sewage entering the lake at around 18 million litres per day. Officials have linked the organic and nutrient content of sewage to the rapid growth of water hyacinth.

The civic body is also constructing an 8 MLD automated sewage treatment plant at the site of a defunct sewage pumping station in Powai. Although the formal deadline is December 2028, the BMC is targeting commissioning by May 2027.

The new plant will treat 8 MLD locally, while the remaining sewage will continue to be sent to the Bhandup STP.

Water-hyacinth removal is continuing alongside the sewage-diversion work.

The BMC said that by September 29 it had removed 20,340 metric tonnes, or 85 per cent, of an estimated 24,000 tonnes of water hyacinth using two harvesters.

Additional municipal commissioner Abhijit Bangar said stopping sewage was only the first stage of the lake clean-up because organic material already present in the lake would remain.

The BMC plans to examine biological interventions after evaluating suitable technologies over the next one to two months.

The completion of the sewage-diversion network marks a major change in the way wastewater from surrounding areas is being handled, with sewage now routed into treatment infrastructure rather than flowing directly into the lake.