India, Aug. 3 -- Amalendu Biswas, a retired government employee from central Kolkata, was often forced to miss office after a downpour as the lane in front of his house would be inundated almost waist-deep. He said Muktaram Babu Street, Manicktala, Thanthania, MG Road, and Chittaranjan Avenue were flooded even after a light rain.

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

Kolkata's over 150-year underground sewerage system has since 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 Kol...