More than 1,000 residents in Chifeng city of the Inner Mongolia autonomous region have fallen ill from drinking water tainted by a polluted lake, local health authorities said yesterday.

More than 1,100 residents of Chifeng's Xincheng district were treated for drinking the contaminated water while 15 others were hospitalized for observation, the Xinhua News Agency reported.

Investigations showed the tainted tap water caused the residents to fall ill following heavy rainfall last week, the local health department said at a press conference.