The water level in the city’s seven lakes has been stuck at 89 per cent for at least two weeks; BMC says nothing to worry about yet. Does BMC have a contingency plan in place in case the rain ditches the city till the end of the season?
Vaitarna, one of the seven lakes supplying water to Mumbai. File pic
In the past fortnight, Mumbai’s drinking water stock from its seven lakes has remained stagnant at 89.2 per cent, even as July — the wettest month of the city’s four-month-long southwest monsoon — has ended.
As of Tuesday morning, the seven lakes that supply water to the city collectively held 12,91,030 million litres, according to the Brihanmumbai Municipal Corporation (BMC). The civic body supplies between 3950 and 4100 million litres of water to the city each day.
At this rate, the present stock could last for 314 days. However, a senior official from BMC’s hydraulics department cautioned that this figure does not take into account losses during transportation due to leakages or evaporation from lake surfaces.
“With around two more months of the monsoon season still remaining, we are not in an alarming situation that could lead to a shortage for the rest of the monsoon calendar, until June 2026,” the official said. On the same date in 2024, lake levels stood at 92.55 per cent, while in 2023 they were at 82.33 per cent.
Ideas mooted for future
The BMC first proposed 4–5 years ago to use water from the city’s seven Waste Water Treatment Facilities (Worli, Dharavi, Bandra, Versova, Ghatkopar, Bhandup, and Malad) for drinking purposes after advanced treatment. The plan involved blending this treated water with that from the Bhandup water treatment plant. “While this idea has been debated, we need to be sensitive to the thought process of Mumbaikars,” a senior civic official said. “Are we, as a city, ready to use water that has gone through advanced treatment and made potable?”
File Pic/Satej Shinde
No feasibility report has been submitted, though the proposal has been discussed by administrators and politicians for the past 3–4 years. Currently, the BMC is implementing a mega-project to provide tertiary treatment at all seven sewage plants, with the treated water to be released into the sea to improve Mumbai’s coastline. According to the 2011 Census, 42 per cent of Mumbai’s population lives in slums.
Long-term plans to augment supply
To reduce Mumbai’s dependence on the seven lakes and boost drinking water sources, the BMC has initiated three major infrastructure projects in the past decade:
Gargai Dam site. File pic/Eeshanpriya MS
Gargai Dam
Location: Wada Tehsil, Palghar District (110 km from Mumbai)
Status: State government clearances in place; central government clearance from the Wildlife Board awaited. Of the 658 hectares required for compensatory afforestation, 380 hectares have been identified near Tadoba National Park in Chandrapur and Washim.
Timeline: 3–4 years
Capacity: 440 MLD
Pinjal Dam
Location: Khidse Village, Jawhar Taluka, Palghar District
Status: State in-principle approval granted in 2013; feasibility study complete; preliminary engineering work underway
Timeline: 10 years
Capacity: 865 MLD
Manori Desalination Plant
Status: Tender process ongoing
Timeline: 4 years
Capacity: 200 MLD (expandable to 400 MLD)
Alternate water ideas on the table
A senior BMC official told mid-day in July that while the current Vaitarna and Bhatsa river systems have historically met the city’s needs, contingency plans are essential.
Another senior hydraulics official said the civic body is pursuing a three-pronged strategy:
1 Building new dams to expand supply
2 Setting up the desalination plant
3 Exploring the integration of water from advanced wastewater treatment facilities at the city’s seven sewage treatment plants into the Bhandup complex’s potable water supply
IMD forecast
The India Meteorological Department has predicted light to moderate rainfall for Mumbai, Thane, and Nashik in the coming days. A yellow alert has been issued for Mumbai between August 13 and 16, and for Thane and Nashik districts between August 12 and 16. All seven lakes that supply water to Mumbai are located in these three districts.
Projected water requirement
(Expert Committee Report, December 2018 – “Towards equitable and 24x7 water supply for Greater Mumbai”)
2031: 5,325 MLD (+29.87 per cent over present)
2041: 6,424 MLD (+56.68 per cent over present)
Present available supply: 4128 MLD
Vision: By 2030, achieve universal and equitable access to safe, affordable drinking water
BMC’s current water supply norms
Residential buildings
135 litres per person/capita per day (LPCD)
Slum areas
45 LPCD
Central government norms allow up to 20 per cent of daily supply as non-revenue water
In Mumbai, non-revenue water is 34 per cent, mainly due to:
>> Non-metered connections
>> Leakages in the distribution network
>> Additional losses occur through evaporation from the lakes
Lakes filling up early
This year, Mumbai’s lakes filled up rapidly in the early monsoon and throughout July. Two lakes have already overflowed
Modak Sagar
On July 9 becoming the first to overflow this season
Tansa Lake
On July 23 Day Tasna overflowed
3950-4100 million litres
Quantity of water BMC supplies to city each day
12,91,030 million litres
Total amount of water available in seven city lakes
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