Apartment STPs won’t fix Bengaluru's stormwater drain crisis: Experts

Bengaluru: Sewage Treatment Plants (STPs) in apartment complexes are not a solution to Bengaluru's overflowing stormwater drains, experts said at a city workshop on Friday.

Speaking at a panel discussion, Vishwanath S, Director of Biome Environmental Solutions, said: "The Bengaluru Water Supply and Sewerage Board (BWSSB) must take accountability and responsibility for STPs. While builders can construct them, forcing apartments to maintain them is not ideal."

The workshop, titled 'Strategies for Decentralised Water Reuse in India', was hosted by Well Labs, Bangalore Apartments' Federation (BAF), and Eawag aquatic research.

BDA president Satish Mallya and T Mahesh, Director of Environmental Management and Policy Institute, called for a better and uniform policy for STPs and sewage treatment.

In his keynote address, Ram Prasath Manohar V, BWSSB Chairman, said there was a fundamental shift in how cities approach water management.

"People now focus more on reusing water than on how much is supplied. Reuse of treated wastewater is no longer a peripheral environmental intervention. It is becoming the backbone of urban water security," he said.

He added: "Bengaluru currently treats around 1,348.5 million litres of wastewater every day through 34 centralised STPs. If reliably reused, this volume can meet most of the city’s non-potable demand — industry, construction, cooling, landscaping and lake replenishment — while reducing pressure on rivers and groundwater."

He said reuse proved valuable during the 2024 water crisis by buffering drought impacts and supporting environmental recovery.

"However, nearly 825 MLD of treated water is currently used for lake rejuvenation — Chikkabalapur and Kolar projects from Koramangala-Challaghatta and Hebbal-Nagawara valley projects — and for minor irrigation. Commercial and industrial reuse remains limited, showing the need to scale decentralised systems with robust quality monitoring frameworks," he said.

Manohar also noted that Bengaluru has one of the world’s largest decentralised STP footprints, with an estimated 4,500 apartment complexes, IT parks and campuses operating on-site treatment systems.