Mumbai Turns to the Sea for Water: Why Desalination Could Reshape the City’s Water Future
Mumbai is surrounded by the Arabian Sea, yet one of India’s largest and most densely populated cities has long depended heavily on rainfall and a network of reservoirs for its drinking water. As the city grows and daily demand rises, that dependence is becoming increasingly difficult to manage.
A major response is now taking shape at Manori in northwestern Mumbai. The Brihanmumbai Municipal Corporation (BMC) is developing a large seawater desalination project designed to add a new source of drinking water to the city’s supply system. The project is expected to eventually provide up to 400 million litres of water every day, giving Mumbai another layer of protection against shortages.
The move is significant because it represents a shift in how Mumbai thinks about water security. Instead of relying almost entirely on freshwater stored during the monsoon, the city is preparing to tap a source that surrounds it throughout the year—the sea.
Why Mumbai Is Looking Beyond Its Reservoirs
Mumbai currently receives its water primarily from seven lakes and reservoirs. According to the BMC figures reported in the news article, the city receives around 4,100 million litres per day from these sources, while its estimated daily requirement is about 4,664 million litres.
That creates a gap of roughly 500–600 million litres every day.
On paper, Mumbai's location beside the Arabian Sea might make the solution seem obvious. But seawater cannot simply be treated using conventional drinking-water processes because of its high salt content.
For years, therefore, the city continued to depend on its traditional reservoir system.
The problem becomes particularly serious when rainfall is delayed or inadequate. Mumbai's reservoirs need a dependable monsoon to replenish their stocks. A weak or late monsoon can quickly raise concerns about restrictions and water cuts.
The desalination project is intended to reduce that vulnerability.
The Manori Desalination Plant: What Is Planned?
The BMC is developing the desalination plant at Manori, a coastal location near Malad in northwestern Mumbai.
The project has an estimated cost of ₹4,007 crore and will cover approximately 12 acres. Once both planned phases are completed, the facility is expected to have a capacity of 400 million litres per day (MLD).
The first phase is planned with a capacity of 200 MLD. A second phase could eventually take the overall capacity to 400 MLD.
If the full project reaches its planned capacity, it would become India's largest desalination facility by capacity, according to the report.
Who Will Build and Operate It?
The desalination system is being developed by Israel-based IDE Technologies, which is also expected to operate the plant for 20 years.
Hyderabad-based GVPR Engineers is responsible for the project's civil infrastructure.
The project received coastal-zone clearances from state and national authorities in April. Those approvals include conditions relating to environmental protection, brine disposal, offshore pipeline construction and renewable energy use for part of the plant's considerable electricity requirements.
How Does Seawater Become Drinking Water?
Desalination may sound complicated, but the basic idea is relatively straightforward.
First, seawater is brought into the facility through intake systems. It then passes through filtration equipment that removes larger materials such as sand, seaweed and other debris.
The next stage is the heart of the process: reverse osmosis.
In this system, seawater is pushed at high pressure through specialised semi-permeable membranes. Water molecules can pass through the membranes, while most dissolved salts and other impurities are held back.
The treated water is then processed further and minerals are added before it is considered suitable for drinking.
However, desalination produces another material that needs careful management.
What Happens to the Salt Left Behind?
When salt is removed from seawater, the remaining water becomes much more concentrated. This concentrated material is known as brine.
The Manori project will therefore need carefully managed brine disposal. Environmental safeguards attached to the project's approvals specifically address this issue.
This is important because desalination should not simply solve one water problem by creating another environmental problem in the marine ecosystem.
Proper engineering, monitoring and responsible discharge practices will be essential once the plant becomes operational.
Mumbai's Long Road to Desalination
Mumbai's current desalination push did not appear suddenly.
The idea gained serious attention after the severe water shortage of 2009, when the city experienced daily water cuts. At that time, desalination was considered as a way of reducing Mumbai's dependence on rainfall.
More than 15 years later, the concept is moving toward large-scale implementation.
That long timeline highlights how difficult major urban water infrastructure can be. Such projects require substantial investment, environmental approvals, technical expertise, construction and long-term operating arrangements.
The falling cost of desalination membranes and improvements in technology have also made large-scale desalination more practical than it was in the past.
Why This Project Matters for Mumbai
The biggest benefit is water-source diversification.
At present, Mumbai's water security is closely connected to its reservoirs and the monsoon. Desalination could give the city another source that is not directly dependent on seasonal rainfall.
That does not mean Mumbai will stop needing its lakes.
Instead, desalinated water could work as an additional component of the city's overall supply system.
Greater Protection During Weak Monsoons
A delayed monsoon can create anxiety because reservoirs may not receive enough water at the beginning of the season.
A desalination facility could provide a more predictable supply during such periods, particularly if its production is integrated effectively with the existing distribution network.
Supporting a Growing City
Mumbai's population density and economic activity create enormous demand for reliable water.
Homes need water. Hospitals, schools, offices, hotels, restaurants and industries all depend on it.
As demand increases, adding new supply capacity becomes increasingly important.
The planned 400 MLD capacity would therefore represent a meaningful addition to the city's water system, although it would not by itself eliminate Mumbai's overall supply gap.
The Challenges Mumbai Must Consider
Desalination is not a magic solution.
One major challenge is energy consumption. Reverse osmosis requires considerable pressure, meaning the plant will need a large and dependable electricity supply.
That makes the project's renewable-energy component particularly relevant.
Another issue is operating cost. Building the facility is only the beginning. Maintaining membranes, operating pumps, managing intake systems and handling waste products require long-term expenditure.
Environmental management will also remain crucial.
The sea may appear to be an unlimited source of water, but marine ecosystems are not unlimited resources. Intake systems and concentrated brine discharge must therefore be designed and managed carefully.
Desalination Should Complement, Not Replace, Conservation
Mumbai's new approach should not be interpreted as a reason to waste water.
Desalination can increase supply, but conservation can reduce demand.
Leak reduction, efficient plumbing, rainwater harvesting, wastewater treatment and reuse can all contribute to a stronger urban water system.
The most resilient strategy is likely to combine several approaches rather than depend on one technology.
Mumbai can continue improving its reservoirs while also adding desalination, recycling water where practical and encouraging responsible consumption.
What the Project Could Mean for Mumbai's Future
If successfully completed and operated, the Manori project could mark an important change in Mumbai's relationship with water.
The city would still depend heavily on its traditional reservoirs, but the Arabian Sea would become an additional source of drinking water.
The project could also serve as an example for other coastal Indian cities facing similar pressures. As urban populations grow and rainfall patterns become harder to predict, seawater desalination may become increasingly relevant in coastal regions.
At the same time, Mumbai's experience will demonstrate whether the technology can be integrated into a large city's water network while keeping costs and environmental risks under control.
FAQs
When is Mumbai expected to receive desalinated water?
The project is expected to provide desalinated drinking water by around 2029, with the full planned capacity potentially reaching 400 MLD later depending on the progress of the second phase.
Where is Mumbai's desalination plant being built?
The plant is being developed at Manori near Malad in northwestern Mumbai.
How much water will the plant produce?
The planned total capacity is 400 million litres per day, with the first phase designed for 200 MLD.
How does desalination remove salt?
The project will use a membrane-based process known as reverse osmosis. High pressure pushes seawater through semi-permeable membranes that separate water from dissolved salts and impurities.
Will desalination solve Mumbai's water shortage completely?
No. The planned facility will add substantial capacity, but Mumbai's total daily requirement is larger than the plant's eventual output. Desalination should therefore be viewed as one part of a broader water-security strategy.
Is desalination environmentally safe?
It can be managed responsibly, but environmental safeguards are essential. The treatment process creates concentrated brine, and its disposal must be carefully controlled. The Manori project's approvals include safeguards covering brine disposal and other environmental concerns.
Conclusion
Mumbai's decision to turn toward the sea for drinking water is more than a large infrastructure project. It reflects a changing reality for rapidly growing cities: reliable water cannot always depend on traditional sources alone.
The Manori desalination plant could eventually add up to 400 MLD to Mumbai's water system and provide greater resilience when reservoir supplies come under pressure. But its success will depend on more than construction. Energy efficiency, environmental safeguards, responsible brine management, operating costs and effective integration with the existing network will all matter.
For Mumbai, the future of water may therefore not be about choosing between reservoirs and the sea. It may be about building a diversified system in which both play important roles—while conservation ensures that every drop is used wisely.
Source: The facts and figures in this article are based solely on the NDTV report provided for reference. The analysis and explanatory context above are independently written.