Calcutta: Mayor Sovan Chatterjee on Monday asked the city police commissioner to take action against unlicensed manufacturers of packaged water.

Since February 9, the civic body has raided several stores selling packaged water because of a diarrhoea outbreak in nine south Calcutta wards.

The mayor had said on Wednesday that the civic body found coliform bacteria in a sample of packaged water collected from Baghajatin.

Many residents of Baghajatin depend on packaged water supplied to homes in 20-litre containers.

Civic officials didn't find the mandatory quality certification labels on such containers. One-litre and 500ml bottles had the labels, though.

"I have spoken to the police commissioner. Teams will be formed to raid the manufacturing units of companies that sell packaged water," Chatterjee said on Monday.

The civic body has so far maintained that the potable water supplied through its network is not contaminated and the outbreak didn't happen because of the water it supplies.

Doctors and public health experts have contested it, though.

Even if packaged water containers is responsible for the diarrhoea outbreak, the civic body and the state government cannot shirk responsibility, a civic official said.

"The onus falls on them to check if illegal packaged drinking water is being sold."

An official of the Bureau of Indian Standards (BIS), the organisation that gives the ISI certification, said all packed drinking water should have the ISI mark.

Companies that have the licence to manufacture packaged water will have the IS14543 mark displayed on bottles, the official said. This is the BIS number for packaged drinking water.

The numbers of diarrhoea patients dipped on Monday. A civic official said 73 patients were treated at the Baghajatin State General Hospital between Sunday noon and Monday noon. Besides, 30 patients were treated at the civic health clinics in the nine wards on Monday.