Mumbai is quietly making a name for itself underground with a vast water tunnel web. This network, which recently crossed a major milestone of 100 kilometres, is poised to become the world’s largest within six years.
Mumbai’s Water Tunnel Web
Unlike the water pipelines most cities rely on, Mumbai’s tunnels run deep, typically between 100 and 110 metres below the surface. This depth offers several advantages. Firstly, it significantly reduces the risk of contamination and theft, a major issue that currently leads to a water loss of nearly 35%. Secondly, the deep location makes tampering much more difficult in case of sabotage threats. Finally, gravity assists water flow in these tunnels, making water supply more efficient.
The story of Mumbai’s water tunnels began in 1955 with a 6.7 km tunnel bringing water from Modak Sagar reservoir. Over the years, the network grew with innovative techniques like the New Austrian Tunnelling Method (NATM) used in 1963 and the first deployment of a Tunnel Boring Machine (TBM) in India in 1983.
9.7 Km Ghatkopar-Parel Tunnel
The recent completion of the 9.7km Ghatkopar-Parel tunnel marks a significant step. Built in two phases and even continuing work during the pandemic, this project involved meticulous alignment to ensure the tunnel emerged at the precise location and depth. While water flow through this tunnel won’t begin until April 2026, several other projects are underway. These include tunnels connecting Ghatkopar to Trombay and Powai, and even a long-distance tunnel fetching water from the Yewai Master Balancing Reservoir.
Building these tunnels is no easy feat. Weak rocks and cavities pose challenges, and deep borewells dug illegally within the city are a growing concern. The Brihanmumbai Municipal Corporation (BMC) emphasises the importance of obtaining permission before digging borewells to avoid puncturing these crucial water arteries.
With its expanding water tunnel network, Mumbai is taking a strategic and sustainable approach to securing its water supply. This network, soon to be the world’s largest, is a testament to the city’s foresight and perseverance in tackling its water challenges.
Cover Image Courtesy: Canva (Representative Image)
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