British-era sewerage system turns a corner with precise restoration

Amalendu Biswas, a retired government employee from central Kolkata, was often forced to miss work after a downpour as the lane in front of his house would be inundated till waist.

- Joydeep Thakur

“The scene was almost the same in [various] parts of Kolkata. Photos of boats at Bodyguard Lines in Alipore after a heavy downpour were published in every newspaper,” Biswas said.

However, in 2025, Kolkata’s over 150-year underground sewerage system has turned a corner, overcoming silt and neglect thanks to a mix of technology and targeted restoration. There was hardly any water logging in July, even as Kolkata received the second-highest rainfall for the month since 2010.

Mechanisation has helped in faster and more efficient desilting, which was previously done manually. The work, which started in 2007-08 was scaled up in the last 10 years.

The India Meteorological Department's regional meteorological centre (RMC) recorded 669 mm of rain this July, against anormal of 371mm. RWC head HR Biswas said that there were atleast three days of intense rain in July when Kolkata received over 80 mm of rainfall within hours.

Large parts of Kolkata would earlier get inundated after moderate (15-64 mm) or heavy rainfall (64-115mm). Some pockets were waterlogged even after light rainfall (up to 15 mm).

A Kolkata Police constable said there was hardly any water-logging in Bodyguard Lines despite the heavy spells of rain in July. “Earlier, police personnel would need rubber boats to reach the office after a heavy downpour. Now, at max, there's ankle-deep water after a heavy downpour, but even that recedes fast,” he said.