Mumbai is facing a significant reduction in its water reservoirs, a situation that has become critical as the monsoon season shows no signs of commencing. As of June 19, data from the Brihanmumbai Municipal Corporation (BMC) indicated that the combined storage of the seven key reservoirs supplying drinking water to the city stood at a mere 9.34 per cent. This represents the lowest recorded level for this date in three years, compared to 12.27 per cent in 2025 and 10.24 per cent in 2024.

The stalling of the monsoon for the past eight days has exacerbated the situation, resulting in a continued decline in reservoir levels. The BMC’s Hydraulic Department reported that Upper Vaitarna, the most severely affected reservoir, has fallen below its lowest usable level, leading the BMC to document its available storage as zero.

Another major reservoir, Tansa, is also experiencing significant depletion, currently holding only 3.87 per cent of its useful capacity. In contrast, Bhatsa, the largest reservoir in Mumbai’s network, holds 8.63 per cent, equating to approximately 61,888 million litres, or nearly 46 per cent of the overall useful water within the reservoir system.

Satellite Imagery Analysis Indicates Water Contractions

The decline in water levels has been visually substantiated by satellite imagery. An analysis was conducted using radar images from the European Space Agency’s Copernicus programme, comparing images from early June 2025 and June 2026. The assessment highlighted a visible contraction in water surface areas across several reservoirs, with shallow edges exposed and previous reservoir beds becoming visible. Although this imagery does not quantify the amount of water, it aligns with the BMC’s documented data of declining reservoir levels.

The examination of Upper Vaitarna, Tansa, and other reservoirs reveals an alarming trend in Mumbai’s water supply system. Vihar reservoir stands out with the highest remaining stock at 41.63 per cent, contributing approximately 8.5 per cent to the total current reservoir capacity, while Tulsi and Middle Vaitarna recorded 22.53 per cent and 10.34 per cent respectively.

Water management in Mumbai relies heavily on the seven reservoirs: Bhatsa, Upper Vaitarna, Middle Vaitarna, Modak Sagar, Tansa, Vihar, and Tulsi. While four of the reservoirs are under BMC control, the remaining three are managed by the Maharashtra government, responsible for allocating water supplies to the city.

Unusual Weather Patterns Affecting Monsoon Progress

The challenges posed by the current dry spell are attributed to an unusual weather pattern. Normally, rainfall begins replenishing reservoir levels during the monsoon, which typically arrives in Mumbai by June. This year, however, after reaching parts of southern Konkan and southern Madhya Maharashtra on June 8, the monsoon’s progression halted, primarily due to adverse atmospheric conditions.

The India Meteorological Department identified several factors contributing to this slow advancement, including a lack of strong winds from the Arabian Sea, diminished moisture transport from the western Indian Ocean, and the absence of a robust low-pressure system along the western coast. While conditions are anticipated to improve by June 23, enabling a potential advance of the monsoon into additional areas of Maharashtra, it remains essential for sustained rainfall in the distant catchment areas that feed the reservoirs.

Until the monsoon revitalises the water supply system, approximately four billion litres of water are expected to continue draining from the reservoirs daily, while very little will replenish the dwindling resources. The situation remains critical as stakeholders monitor developments closely in the coming days.

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