Despite frequent overflow alerts during monsoon, the actual water-holding capacity of Mumbai and Navi Mumbai’s drinking water reservoirs may be grossly overestimated — a result of over a decade of neglect in desilting operations, reveals information accessed by NatConnect Foundation. Inquiries made under the Right to Information (RTI) Act by NatConnect have uncovered that no desilting has been carried out in major drinking water sources of Mumbai — including Vihar, Tulsi, Modak Sagar, Tansa, and Middle Vaitarna — over the past 10 years, as confirmed by the Brihanmumbai Municipal Corporation (BMC). "This lack of desilting explains why the city faces water cuts as early as April or May, despite lakes appearing full during the monsoon,” said B N Kumar, director of NatConnect Foundation.
The status of the remaining two reservoirs — Bhatsa and Upper Vaitarna — remains unclear, with no response from the BMC. These seven lakes collectively supply 3.4 billion litres of water to Mumbai every day. Navi Mumbai faces a similar situation. The city relies solely on the Morbe Dam, which supplies 450 million litres of water daily. In response to NatConnect’s query, Morbe Dam Deputy Engineer Maruti Ambedkar admitted that no desilting has been done since the dam was taken over by the Navi Mumbai Municipal Corporation (NMMC). Kumar emphasized that the accumulation of silt in the reservoirs leads to a dangerous misconception that all is well with the water supply. “The silt reduces the actual storage capacity of lakes, while people are left scrambling for expensive tanker water — fueling a multi-crore tanker mafia,” he added.
Concerned about this lapse, Kumar had also approached the Maharashtra Urban Development Department. Shockingly, the department replied that it had no records of desilting work in water reservoirs. “This is an essential civic function. How can the state not monitor drinking water security in rapidly growing cities?” Kumar questioned. Following this, the RTI application was redirected to the BMC. The civic body’s Ghatkopar Water Works office confirmed that no desilting work had been done at Vihar and Tulsi lakes — and consequently, no funds had been spent either. Similar responses came from BMC's Hydraulic Engineer’s department in Kapurbawdi, Thane, regarding Modak Sagar, Tansa, and Middle Vaitarna. Kumar expressed dismay that while BMC has allocated over ₹250 crore for drain desilting as part of monsoon preparedness, it continues to ignore the critical need for desilting its drinking water sources.
Supporting the call for urgent action, Nandakumar Pawar, head of Shri Ekvira Aai Pratishthan, said the absence of desilting is a key reason behind dam overflows and the resulting riverine floods. “The sludge at the reservoir bottoms is mineral-rich and can be used to rejuvenate farmlands,” he said. Both Kumar and Pawar stressed that using the silt for agriculture could help combat widespread topsoil erosion, a major issue in farming today.
They have jointly appealed to the government to constitute a high-level expert committee comprising hydraulic engineers and agricultural experts to assess the situation and recommend a comprehensive desilting and resource utilization strategy. NatConnect has written to the Chief Minister, urging him to bring all stakeholders together and act swiftly to safeguard both urban water security and rural soil health.