Treatment of Surface Water Used for Private Drinking Water Supplies

Since its inception, the Council has worked on several issues relating to the need to treat drinking water derived from surface water sources.  In fact, the Council, in Recommendation #13 of its “Report and Advice on Ontario Regulation 170/03 Smaller Private Systems Review and Recommendations” recommended that “…all surface water source drinking water systems should require some form of treatment…”. This recommendation related specifically to systems covered under O. Reg. 170.

The issue of treating surface water also arose during the Council’s deliberation on O. Reg. 903, which currently requires that all wells, including wells that are Groundwater Under the Direct Influence of surface water (GUDI), be able to produce potable water, when they are to be used as a source of water for human consumption.

In this light, it has come to the Council’s attention that private and other unregulated systems that use surface water as their source for drinking water are the only category of system to have no regulatory requirements for installation, treatment, or the provision of potable water.

The Council deems untreated surface water to be inherently unsafe for use as drinking water, due to the highly variable and highly vulnerable nature of the source.  Untreated surface water poses a potential risk to human health and requiring treatment on these types of installations will have likely human health benefits.

The Council transmitted its final advice letter to the Minister of the Environment on this issue, on April 10, 2006.

Click here to view the Council's advice.