Environmental groups are applauding proposed legislation intended to prevent another Walkerton tainted-water tragedy, but warn it must be flexible enough to tackle new threats to Ontario's water supplies.

Public hearings got underway in Toronto Monday to hear concerns about the Clean Water Act, which was introduced last December to address water safety in the province.

"Let's not kid ourselves and think that E. coli is the last threat to water we're going to see. There are going to be other water-borne pathogens," said Bruce Davidson, spokesman for the Concerned Walkerton Citizens group.

Davidson argues the bill must not only be capable of dealing with the problem that plagued his community, but also adaptable enough to target emerging dangers to the water supply, such as new chemicals and different problems caused by urban sprawl.

Seven people died and thousands fell ill after drinking water tainted with E. coli that had seeped into Walkerton's supply.

An inquiry blamed provincial oversight of water quality and poor operation of the water system.

The Clean Water Act outlines a process to help identify contaminated water. It is not expected to become law until later this year.

Concerns over cost, scope of implementation

Davidson called it an important piece of legislation that he hopes will go through because it gives the government the power to investigate concerns about water supply, he said.

But he warned there are many concerns about the cost and sheer scope of implementing the act.

Some are also questioning how it will be applied in areas outside the reach of conservation authorities such as much of the northern part of the province and how First Nations communities will be included.

Davidson said his group will push for a more comprehensive piece of legislation, but says it is important to see the bill pass.

The Ontario Medical Association has also thrown its support behind the act, calling it a big step forward for water protection.

Public hearings will continue across the province in Walkerton, Cornwall, Bath and Peterborough.