Drinking Water Protection in Ontario

An Introduction to the Multi-Barrier Approach to Drinking Water Protection

The multi-barrier approach to drinking water protection is the systematic protection of water in every phase of the drinking water cycle. Under this approach, it is ensured that water processed at water and wastewater treatment facilities is subject to rigorous and ongoing testing; that the infrastructure of municipal water distribution systems is kept in excellent repair; that raw or source water that will be used for drinking is uncontaminated; and that potential threats to drinking water are communicated to all parties involved in the approach’s implementation.

A multi-barrier approach to protecting drinking water was taken up in earnest by the province of Ontario in the wake of the tragedy at Walkerton, Ontario in May 2000. During this event, seven people died and approximately half the town’s 4,200 residents became sick; hundreds continue to live with severe health problems and social impacts. This tragedy resulted from the failure of an entire regulatory framework and oversight system responsible for protecting water sources; a failure to address threats to the quality of drinking water; and poor communication among decision makers at the provincial government, the municipality’s water system managers and the region’s water treatment laboratory.

In response to the results of the Walkerton Inquiry, which was established to determine the cause of the tragedy, and the final recommendations made by Justice Dennis O’Connor, the province moved towards a multi-barrier approach, passing two important laws intended to protect drinking water. In 2002 the government passed the Safe Drinking Water Act, which addresses water treatment and distribution systems. In 2006, the Clean Water Act, a source water protection law, was passed. These Acts are now being implemented.