Mumbai: Lakes 98 per cent full, but water cuts may continue

Mumbai may face water cuts this year, too, owing to insufficient storage, even as the seven lakes - which provide water across the city - were 98 per cent filled by the last week of September. The July rain had already filled up lakes, and a few showers in August and September have kept the levels high. However, going from past experiences, parts of the city may face water cuts this year, too, as the current storage is insufficient for the vertically expanding city.

The total storage capacity of all seven lakes supplying water to the city is 14,47,363 million litres. Currently, as of September 24, the combined storage of all seven lakes stands at 98.29 per cent, almost similar to last year (98.68 per cent) and the year 2022 (98.97 per cent).

Visitors enjoying at the Vihar Lake as the lake overflows in the month of July. File Pic/Satej Shinde

Earlier, if all lakes were full by the end of September - officially the last day of monsoon season - then the water stock would be enough till the next monsoon. But, going by the experience of the past few years, there is a strong possibility of water cuts before the arrival of the next monsoon.

In the years 2021, 2022, and 2023, the lakes were 100 per cent full by the end of the monsoon season, and still parts of the city faced water cuts. Mumbai's daily water supply requirement is about 4,500 million litres, but the Brihanmumbai Municipal Corporation (BMC) was able to provide about 3,850 million litres, leading to water cuts.

The difference between demand and supply has been increasing, but that is not the only reason behind water cuts. "Earlier, the monsoon used to arrive in the first week of June. But, for the past few years, the monsoon has been delayed to the last week of June or early July. It takes two weeks to revive the water table after the rain begins. Thus, the corporation imposes cuts to keep the stock till the water level increases," said an official from the hydraulic engineering department.

Water cuts

2022: 10 per cent water cut from June 28 till July 12 as storage dipped nine per cent due to delay in monsoon.

2023: 10 per cent cut from July 1 till August 2. The stock went down by seven per cent in June even after using the reserved stock, again due to delay in monsoon.

2024: Five per cent water cut from May 30 till June 5 and 10 per cent cut from June 5 to July 28 when the stock went down by 10 per cent. The BMC had to borrow 65,700 million litres of water from Upper Vaitarna and Bhatsa.

Why is current storage low?

The water requirement not just depends on population but also on floor space index. The per person per day requirement in slums is much lower than the requirement for people living in high-rise buildings, and that is why the requirement for daily water needs has been increasing constantly. The city's requirement is currently 4,500 million litres per day, which could rise to 5,000 million litres in the next five years.

How can storage be improved?

To match the demand-supply ratio, the desalination project at Manori, which can add 200 million litres per day of water after three years, will help to some extent. The capacity can be later expanded to 400 million litres per day. In addition, the BMC has formulated to construct the Gargai dam in the Tansa Sanctuary, which could add another 400 million litres per day to the city's supply.

2022
Year when cuts started being imposed, as stock dipped to an unprecedented 9 per cent