Mumbai has just 40 days of water left as BMC reviews supply strategy amid monsoon delay

The Tansa lake in the Shahapur taluka of Thane district. It is one of the seven such water bodies that supply water to Mumbai and have a total capacity of 14,47,363 million litres. File Pic

With about 40 days of drinking water stock remaining and June reaching its mid-way point without the southwest monsoon arriving, the Brihanmumbai Municipal Corporation (BMC) will work out a strategy on Tuesday on how to weather the situation.

Catchment situation

This year, the catchment areas of the Tansa and Modak Sagar lakes have received 13 mm and seven mm of rainfall while those of the other lakes have not received any rain, according to information from the BMC. This has resulted in a rapid depletion of the existing water stock. However, this year's stock still exceeds the water available on the same day last year - 8.69 per cent or 1,25,824 million litres. In 2024, the water stock in the seven lakes was at 78,889 million litres, or 5.45 per cent.

Water worries

The drinking water stock in the seven lakes that keep Mumbai hydrated - Tansa, Vihar, Tulsi, Bhatsa, Upper Vaitarna, Modak Sagar, and Middle Vaitarna - has depleted to 1,55,167 million litres, with the BMC drawing around 3950 million litres of water per day (MLD). Even though the lakes are only 10.72 per cent full, the civic administration said they were approaching the situation with caution. On May 15, the BMC started imposing an ongoing 10 per cent water cut, taking the daily supply down from 3950 MLD/4100 MLD to approximately 3,650 MLD.

The May water cut

The decision was taken after the India Meteorological Department (IMD) indicated a weak southwest monsoon due to the effect of El Nino, with only about 90 per cent of rainfall expected this monsoon. On an average, Mumbai receives about 2300 mm of rainfall each year. On May 15, the lakes were 23.12 per cent full, with 3,34,643 million litres of water. The BMC decided to impose the 10 per cent water cut to ensure that the available water stock would suffice till the end of July, considering a weak monsoon. If the water stock is replenished during this year's monsoon, it will suffice until the onset of next year's monsoon season (June 2027).

May 15
Day imposition of 10 per cent water cut began