Mumbai’s civic body is set to bolster its drainage system to manage up to 120 mm of rainfall per hour after severe flooding from late May downpours. The expansion aims to tackle persistent waterlogging issues, reduce flood risk, and strengthen the city’s resilience against increasingly erratic monsoons. Mumbai’s drainage woes returned on 26 May when nearly 200 mm of rain fell within hours, highlighting the limitations of ageing infrastructure.
Built originally to channel only 25 mm of rainfall per hour, primary drains were subsequently upgraded to 55 mm capacity post 2006 floods. But recent deluges overwhelmed that system, prompting the Brihanmumbai Municipal Corporation (BMC) to propose a significant capacity jump to 120 mm. Currently, the city maintains roughly 261.5 km of major drains and 411.6 km of minor drains, alongside 3,800 km of other drainage channels.
To guide expansion plans, BMC has engaged universities and technical institutes to assess hotspot zones and recommend optimal structural changes. Officials plan to install debris blocking mesh on inlets and optimise local water flow through community feedback campaigns. The effort seeks to reduce water stagnation in slums, low lying suburbs, and island city pockets that are particularly vulnerable during intense monsoon bursts.
Beyond engineering, civic experts stress the links between drainage upgrades and broader city planning. As Mumbai’s population grows and rainfall variability deepens under climate change, resilient cities must integrate sustainable infrastructure. A senior planner explains that green corridors, permeable surfaces, and enhanced vegetative cover help absorb excess water, mitigate heat island effects, and recharge aquifers. By enhancing both hard and natural drainage systems, Mumbai can align with zero carbon, eco friendly city models and protect vulnerable communities equitably.
However, challenges remain. Budget constraints and the sheer scale of drainage networks pose coordination issues across municipal departments. Removing debris from older colonial era drains, many silted since they were laid decades ago, requires extensive community mobilisation and oversight. Meanwhile, targeted public awareness drives aim to limit household dumping and promote shared responsibility. Civic agencies acknowledge that effective waterlogging defences demand both technical solutions and sustained citizen involvement.
Similar schemes in other metropolises highlight that drainage modernisation must be part of broader climate adaptation strategies. Measures such as early warning systems and emergency evacuation plans will also be necessary alongside infrastructure upgrades. For Mumbai, expanding capacity from 55mm to 120mm per hour is more than an engineering feat—it’s a test of the city’s ability to adapt, protect its residents, and pursue sustainable urban growth in an era of climate uncertainty.
