BMC Approves ₹2,241 Crore Tunnel Project to Connect Manori Desalination Plant With Mumbai Water Network

7.2-km Underground Tunnel to Strengthen Mumbai’s Future Water Supply by 2029

Mumbai is moving one step closer to securing an additional source of drinking water after the Brihanmumbai Municipal Corporation (BMC) approved a ₹2,241.3 crore underground tunnel project that will connect the upcoming Manori desalination plant to the city’s water distribution system. The proposal received clearance from the BMC Standing Committee following detailed discussions on water quality, project planning, and construction methods.

The new tunnel will transport desalinated seawater from the Manori plant into Mumbai’s water network. Officials expect the project to begin in August and complete within 45 months, with commissioning targeted for December 2029.

Underground Tunnel Designed for Future Water Demand

The project includes the construction of a 7.2-kilometer underground tunnel running from Manori to Charkop and Mahavir Nagar in Kandivali, passing beneath sections of Gorai Creek.

The 3.2-meter-wide tunnel will initially carry 200 million liters of desalinated water per day (200 MLD). However, it has been designed to handle up to 400 MLD in the future, allowing the city to increase water supply as demand grows.

BMC has proposed awarding the contract to Afcons Infrastructure Ltd., which will be responsible for the design, construction, operation, and maintenance of the tunnel and related infrastructure.

Two Tunnel Boring Machines to Speed Up Construction

To complete the project faster, two tunnel boring machines (TBMs) will work simultaneously.

The project also includes:

• A receiving shaft at the Manori desalination plant.
• A new shaft at Charkop.
• A connection to the existing Mahavir Nagar shaft in Kandivali.

Officials explained that the Charkop shaft will only serve as a transmission point and will not be used for water extraction or distribution.

Standing Committee Members Raise Questions

During the Standing Committee meeting, several corporators raised concerns about the project before approving it.

Shiv Sena (UBT) corporator Yashodhar Phanse asked whether desalinated water would match the quality of water currently treated at Mumbai’s Bhandup Water Treatment Complex. He also emphasized the need to train BMC staff to manage modern desalination technology.

Congress leader Ashraf Azmi questioned why the desalination plant and the transmission tunnel were awarded through separate tenders instead of one combined contract. He also sought clarification regarding the 16% contingency provision included in the project estimate.

Congress corporator Tulip Miranda expressed concerns about mixing desalinated water with the city's existing lake water supply. She requested details on safety measures related to mineral content and chlorine levels to ensure public health is protected.

BMC Says Water Quality Will Meet Existing Standards

Responding to the concerns, Additional Municipal Commissioner (Projects) Abhijeet Bangar assured committee members that desalinated water will meet the same quality standards as water supplied from the Bhandup Water Treatment Complex before it enters Mumbai’s distribution network.

He said the tunnel will feature 5.1 kilometers of reinforced cement concrete (RCC) lining, while the remaining section will use mild steel lining protected by concrete. The contract also includes strict penalties for any leakage during operation.

Bangar explained that although the desalination plant and tunnel are part of one integrated water supply system, separate tenders were issued because the desalination facility requires specialized international expertise.

He also stated that the 16% contingency provision follows standard industry practice and reflects an estimated annual construction cost escalation of about 4%.

Manori Desalination Plant to Become Mumbai’s First Seawater Project

The Manori desalination plant will be Mumbai's first large-scale seawater desalination facility. The tender for the project was issued in December 2023 for a 12-hectare site at Manori.

GVPR Engineers Ltd. secured the contract worth ₹11,166.17 crore. The total cost includes approximately ₹4,077 crore for construction, while the remaining amount covers 20 years of operations, maintenance, power expenses, taxes, and other lifecycle costs.

Once operational, the desalination plant and its transmission tunnel are expected to improve Mumbai's long-term water security by providing a reliable alternative source of drinking water, while leaving room for future expansion as the city's population and water demand continue to rise.