July downpours lift Mumbai's reservoir levels to 3-year high despite delayed monsoon

Heavy rainfall in July has pushed water levels in Mumbai's seven reservoirs to their highest for this time of year in three years, reversing concerns triggered by a delayed monsoon and improving the city's water security.

The combined live storage in the seven lakes supplying Mumbai stood at 12.85 lakh million litres, or 88.81% of their total useful capacity of 14.47 lakh million litres, on Tuesday morning, according to data from the Brihanmumbai Municipal Corporation (BMC).

The level is marginally higher than the 88.70% recorded on the same date last year and well above the 72.97% reported on July 28, 2024.

Mumbai draws its year-round water supply from seven reservoirs—Tulsi, Vihar, Bhatsa, Tansa, Modak Sagar, Upper Vaitarna and Middle Vaitarna—located across Mumbai and neighbouring Thane, Palghar and Nashik districts.

Four reservoirs reach full capacity

According to the BMC, Tulsi, Vihar, Modak Sagar and Tansa have reached 100% useful capacity.

Middle Vaitarna was at 90.3%, Bhatsa at 87.36%, and Upper Vaitarna at 77.51%.

During the 24 hours ending Tuesday morning, Upper Vaitarna received 85 mm of rainfall, followed by Bhatsa with 72 mm and Modak Sagar with 57 mm.

July rainfall offsets delayed monsoon

The improvement follows a difficult start to the monsoon season. In May, reservoir storage had fallen below 25%, prompting the BMC to impose water cuts after the India Meteorological Department (IMD) forecast below-normal monsoon rainfall under the influence of El Niño conditions.

Although the southwest monsoon, which normally reaches Mumbai in early June, arrived only on June 30, exceptionally heavy rainfall during July helped replenish the reservoirs.

The IMD's Santacruz observatory recorded 1,490 mm of rainfall during July, substantially higher than the city's average July rainfall of 919 mm.

Despite the improved reservoir levels, the BMC said existing water cuts would continue until the combined storage reaches 100% capacity.

The civic body currently supplies about 3,850 million litres per day (MLD) against an estimated daily demand of 4,300 MLD, leaving a shortfall of around 450 MLD.

Rainfall likely to pick up again

Rainfall eased across Mumbai on Tuesday morning. During the 24 hours ending Tuesday morning, the eastern suburbs received 19.39 mm of rain, while the island city and western suburbs recorded 10.82 mm and 10.68 mm, respectively.

The IMD has forecast light to moderate rain over the city and suburbs during the next 24 hours.

The BMC also warned of high tides of 4.01 metres at 11.45 am and 3.5 metres at 11.30 pm.

The IMD has issued a yellow alert for Mumbai, Thane and Palghar from Friday, forecasting thunderstorms, lightning, moderate rainfall and gusty winds of 40-50 kmph.