The monsoon has been erratic, heavy showers separated by long dry spells, but the waterlogging has been consistent.
And the Calcutta Municipal Corporation (CMC) warns of worse to come ' despite an ambitious Rs 36-crore programme having been flagged off last year to revamp the drainage system.
The civic body's report card reflects a resounding failure, evident from the water mark on thoroughfares after every sharp shower.
'Calcuttans may face severe waterlogging in the event of heavy showers this monsoon,' confirms N.R. Samanta, acting chief engineer (drainage and sewerage) of the CMC.
Despite a patchy monsoon, the city went under water on two occasions ' July 11 and 13. Arteries like BB Ganguly Street, Amherst Street, Bidhan Sarani, Rafi Ahmed Kidwai Road, Ganesh Chandra Avenue and College Street were all waterlogged.
Even the stretches considered 'safe' ' Kiran Shankar Roy Road, roads around Raj Bhavan and Calcutta High Court, the thoroughfare in front of Writers' Buildings, Ballygunge Phari, Hazra, Gariahat Road, Maniktala, Bakultala and Raja SC Mullick Road ' were found to be flood-prone.
According to officials at the Alipore Met office, the city received 112.5 mm of rain on July 11 and 85.9 mm on July 13. On July 11, 57.6 mm of rain was concentrated between 5.30 pm and 8.30 pm.
According to officials, the city's drainage system had the capacity of clearing out 12 mm of rainwater in an hour, pre-Independence. 'But over the past 50 years, the capacity has been halved,' they said.
Alarmed at the waterlogging despite rainfall that was 'hardly unusual', deputy mayor Kalyan Mukherjee and municipal commissioner Alapan Bandyopadhyay convened a special mayoral council meeting last Friday to review a drainage revamp.
Mayoral council member (drainage) Farzana Chaudhury admitted to a 'lack of co-ordination' between the chief engineer and the drainage pumping stations.
If the pumps are operated, the drainage capacity rises to 40 mm an hour, said a former chief engineer.
The failure to desilt sewers, gully pits and open drains, despite Rs 16 crore being allotted for the purpose last year, as part of the mega drainage plan, is also cause for concern.