“Kolkata does not have floods. Kolkata is a flood.”
Kolkata Waterlogging & Drainage
38 chronic hotspots, 27 pumping stations, and 150+ years of living with water
Kolkata's sewers have been running since 1868, and the original network was designed to drain 19.1 square kilometres of the central district. The city it now serves is more than ten times that area, and the KMC Monsoon Book lists 38 chronic waterlogging pockets — 22 of them classified high severity, most flooding annually.
Against that sit 27 pumping stations with a combined capacity of about 7,423 cusecs. The constraint is rarely the pumps. On 23 September 2025, 234 mm of rain fell in six hours, peaking near 98 mm an hour — a rate no gravity-fed Victorian sewer, however well maintained, was built to carry.
About this data
What this page shows
Mapped waterlogging hotspots with severity and recurrence, the pumping station network and its capacity, borough-level flood vulnerability, drainage infrastructure facts, and a table of major flood events with rainfall and impact. KMC removed over 200,000 metric tons of silt in FY2024–25, and 88 km of brick sewer is targeted for revamp, of which around 30 km has been desilted since 2005 under JNNURM.
Where the data comes from
The KMC Monsoon Action Plan (Monsoon Book 2021), the West Bengal Irrigation & Waterways Department's drainage documentation, published research on post-Amphan flood vulnerability, and contemporaneous news reporting for individual flood events.
Limitations worth knowing
The hotspot list records where flooding is known and repeatedly reported, which is not the same as a systematic survey — areas with less press attention or political weight may be under-represented. Severity ratings are qualitative categories carried over from the source material, not measurements of depth or duration, and the underlying municipal document dates to 2021. Rainfall figures attached to individual flood events come from contemporaneous news reporting and may differ from IMD's official station records. See the data coverage note above for how locations were geocoded.
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