Health officials in India's flood-hit city of Kolkata said on Thursday they were worried about the outbreak of disease, as residents drank and swam in the filthy, neck-deep water.

Rains have swamped homes and disrupted power in the eastern city of more than 8 million people. Most schools were closed for the third day running and many offices empty as people avoided going to work through the flooded streets.

More bad weather was forecast, and authorities used sandbags to shore up embankments along the Hooghly River.

Health workers in boats distributed rehydration packets and medicine as reports of skin infections and fever came in from some areas.

"Each time I wade across the flooded streets, my skin starts burning," Ravindra Shaw, 33, a resident said.

As overflowing sewage mixed with rain water, health experts worried about the outbreak of disease.

"We are warning children not to swim in these waters and avoid wading across the streets just for fun as this could be hazardous," said Deb Dwaipayan Chattopadhyay, a senior health department official.

Many people also do not have clean drinking water. "With safe drinking water reserves gone, people have no choice but to opt for contaminated water to survive," said Deepika Sur, a top official at the National Institute of Cholera and Enteric Diseases.