Chennai responded to its water crisis with long-term investments, while Mumbai continues to rely primarily on reservoirs and seasonal rainfall. Every summer, Mumbai faces concerns over its water supply as reservoir levels decline and the city waits for the arrival of the monsoon. This year has been no different, with the city once again imposing water supply cuts. The move has reignited debate over Mumbai's long-term water security and its continued dependence on seasonal rainfall. Recurring Crisis With reservoir levels falling and the monsoon yet to arrive, concerns over water availability have intensified across Mumbai. The situation was further complicated by a strike by water tanker operators, while civic authorities responded with supply restrictions and conservation measures. Among them was a 20 per cent reduction in water allocated to industrial units, commercial establishments and sports clubs. Yet the larger question remains largely unaddressed: why does a city with more than 150 kilometres of coastline continue to face recurring water shortages whenever monsoon rainfall falls short of expectations? Mumbai is India's financial capital and receives substantial annual rainfall. With more than 150 kilometres of Arabian Sea coastline, the city would appear well-positioned to ensure water security. Yet its water supply remains heavily dependent on reservoirs and the monsoon. A weak monsoon, prolonged dry spell or the growing impact of climate change can quickly push Mumbai towards a water crisis. Yet another coastal city faced a similar challenge and chose a different path. Chennai acted. Mumbai now faces a similar choice. Chennai's Lesson Chennai, too, once struggled with severe water shortages. In 2019, its reservoirs nearly ran dry, bringing the city to the brink of a major water crisis. Instead of remaining dependent on rainfall alone, Chennai invested in long-term water security measures. Desalination became a key part of its strategy, alongside rainwater harvesting, wastewater recycling and groundwater recharge initiatives. The city recently commissioned the Perur Desalination Plant, which will add 400 million litres of drinking water a day to its supply network. Once operational, Chennai's total desalination capacity will reach about 750 million litres per day, strengthening its position as India's leading desalination hub. Chennai's experience offers an important lesson: coastal cities have options if they are willing to invest in long-term water security. Mumbai and Chennai share many similarities. Both are large coastal metros with populations exceeding 10 million and remain heavily dependent on the monsoon. The difference is that Chennai responded to its water crisis with long-term investments, while Mumbai continues to rely primarily on reservoirs and seasonal rainfall. Beyond Monsoons Mumbai's water strategy remains heavily dependent on reservoirs, lakes and seasonal rainfall, despite the city being surrounded by the Arabian Sea. Desalination is no longer an experimental solution. Countries such as Israel, Singapore, Saudi Arabia, Australia and the UAE rely on desalinated water as a dependable source of urban supply. Chennai has also demonstrated how desalination can become an integral part of a city's water security strategy. The question is whether Mumbai is prepared to make similar investments before shortages become more frequent and severe. Future Risks The question is not whether Mumbai will face water shortages, but how severe those shortages could become in the years ahead. Climate change is making monsoon patterns increasingly unpredictable. Population growth, rising industrial demand and declining groundwater levels are placing additional pressure on existing water sources. Continued dependence on reservoirs and seasonal rainfall leaves the city vulnerable to recurring water stress. Diversifying water sources has therefore become a necessity rather than an option. Water security will ultimately require a combination of measures, including desalination, wastewater recycling, rainwater harvesting, groundwater recharge and improvements to distribution infrastructure. Desalination offers one such alternative. In addition to supplementing drinking water supplies, it can reduce pressure on reservoirs, support industrial demand and strengthen resilience during years of below-normal rainfall. The technology is neither new nor untested. Countries such as Israel, Singapore, Saudi Arabia, Australia and the UAE have integrated desalination into their long-term water security strategies. During his 2017 visit to Israel, Prime Minister Narendra Modi was shown desalination technologies capable of converting seawater into potable water efficiently and at scale. Mumbai has repeatedly demonstrated its ability to execute complex infrastructure projects, from the Bandra-Worli Sea Link to the Metro network and the Coastal Road. Water security deserves the same long-term vision and commitment. It is time for the Maharashtra government and the Brihanmumbai Municipal Corporation (BMC) to move beyond short-term measures and adopt a comprehensive water security strategy that combines desalination, rainwater harvesting, wastewater recycling, groundwater recharge and infrastructure upgrades. The choice is clear: continue relying primarily on the monsoon, or invest now in a more resilient and secure water future. (The author is a resident of Mumbai. Views personal.)
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