Mumbai is preparing to do something it has never done before: draw a meaningful share of its drinking water from the sea. The Brihanmumbai Municipal Corporation (BMC) is moving ahead with a seawater desalination plant at Manori, a coastal village at the northern edge of the city’s suburbs, in what will be Maharashtra’s first large-scale desalination facility.
The project addresses a structural problem that has become harder to ignore. Mumbai draws roughly 4,100 million litres a day (MLD) of drinking water from seven monsoon-fed reservoirs across Thane, Palghar and Nashik, against a daily requirement the BMC puts at 4,664 MLD — a shortfall of 500-600 MLD even in an average year. This summer exposed how thin that margin really is: by mid-May, usable reservoir stock had fallen to 23.5% of the city’s annual requirement, triggering a 10% citywide water cut, and by mid-June it had dropped to just 10.35%, forcing additional cuts to industrial and commercial users and a full suspension of supply to construction sites and swimming pools.
A 400 MLD plant built around resilience, not just capacity
The Manori plant is designed in two phases. The first, costed at roughly Rs 3,900 crore (about $470 million), is expected to deliver 200 MLD by 2029; a second 200 MLD phase would bring total capacity to 400 MLD by around 2030. Israel’s IDE Technologies — the firm behind Ashkelon, Hadera and Sorek, some of the most closely watched reverse osmosis plants in the world — will supply the RO technology and operate the facility for 20 years, while Hyderabad-based GVPR Engineers handles civil construction.
Rather than laying seawater intake and brine discharge pipes across the seabed, the project will bore three tunnels beneath it — two intake, one outfall — running roughly seven kilometres out to sea at about 2.8 metres in diameter each, specifically to avoid disrupting fishing grounds and coastal ecosystems. The design followed nearly two years of bathymetric, sonar, tidal and geological surveys. Regulatory sign-off has already included conditions on brine dispersal, mangrove protection and renewable energy use, with the Ministry of Environment’s Coastal Regulation Zone clearance requiring BMC to monitor long-term brine impacts on marine ecology.
Notably, BMC and IDE intend to run the plant on renewable power — a mix of solar, wind and battery storage designed to offset grid consumption around the clock, which officials say would make Manori India’s first desalination plant powered entirely by renewable energy, if realised as planned.
One piece of a three-part diversification strategy
Manori is the most advanced of three projects the BMC is pursuing to reduce Mumbai’s near-total dependence on rainfall. The others are the 440 MLD Gargai dam, still awaiting environmental clearance, and a second, earlier-stage 200 MLD desalination plant planned for Versova. Together, the three could add 1,040 MLD of new capacity — though even at full build-out, officials and IDE’s own India sales director are candid that desalination alone will cover only a fraction of demand: the initial 200 MLD phase would meet around 5% of current requirement, rising to 8-10% once the plant reaches full capacity.
That framing matters. Mumbai’s planners increasingly describe desalination not as a replacement for reservoirs but as one leg of a diversified supply — alongside continued dam-building and a longer-term push to treat sewage effluent to potable standard, as is already being explored for the Colaba and Worli treatment plants.
The tunnelling contract for Manori’s seawater conveyance, awarded to Afcons Infrastructure for roughly $200 million, is already under way — see our earlier coverage of that contract for more on the tunnel route and timeline. With permissions now in place, BMC says full construction on the plant itself will begin once this year’s monsoon season ends.
Source: ThePrint