"These drains carry out rain water from localities to the river. Without this system, colonies simply wait and watch for the water to dry up," he said.

Kankerbagh, a locality known to be highly prone to waterlogging, has several structures constructed over its drainage network, he said. "Such illegal constructions further compound the problem," he said.

It is learnt that the PWB has drawn up a list of all buildings that have covered drains so that action can be initiated against them on priority.

Patna Municipal Corporation commissioner K P Ramaiah said, "We have conducted a survey in Kankerbagh and have found that many houses have been constructed over the drains. We will next survey Postal Park."

He said local residents have been helping the municipal corporation in these surveys as they want the drainage system to be freed.

A source said the Patna Regional Development Board had promised prompt action against the offenders.
Patna has a natural terrain that makes drainage of water difficult.

A PWB engineer said, "Patna,s terrain is like a saucer, with high edges and a low-lying centre. So there are few natural channels of drainage."

Over the past several years, poor maintenance and faulty repairs have harmed the sewerage and drain network. The engineer said, "We have noticed that at many places the sewage pipes have been connected to the storm water drains.

This not only leads to untreated waste falling into the river but also eventually chokes the storm water pipes."

Bihar Rajya Jal Parshad (BRJP), the agency responsible for sewage and drainage, owns 18 pump-sets that are stationed in different parts of the city to pump out water. Five pumping sets earlier owned by PWB have been passed on to the Parshad.

On Tuesday, the pump-set at Sri Krishnapuri did not work and the main Sri Krishnapuri and Boring Road intersection remained waterlogged for the first half of the day.