Walkerton's water may have killed three more

The worst E. coli outbreak in Canadian history may be deadlier than first thought. Ontario's chief coroner is investigating reports of three more possible victims of Walkerton's contaminated water.

James Young says seven people are known to have died as a result of the E. coli bacteria in the water. His office has also been investigating four other deaths.

On Thursday, Young announced three more women have been added to the list. Two of them were elderly and died in Walkerton. The third who was 27 died in Kitchener.

More than one out of every three of Walkerton's 5,000 residents became extremely ill after drinking the contaminated water last month.

The coroner has asked people in the southwestern Ontario farming community to report any suspicious deaths that occurred before people were told about the outbreak May 23.

Investigators say they may never know what happened. One theory is that a severe rainstorm washed E. coli from cattle manure into the community's water system. There is also evidence that purification equipment wasn't working properly.

Health officials have accused the local water utility of failing to notify them about the presence of deadly bacteria in at least one well until it was too late.

Opposition politicians claim the government of Ontario is partly responsible because of changes to the way drinking water is monitored in the province.