Source water is the untreated water in lakes and rivers, and in underground aquifers, that people use for drinking water. Source water protection means protecting our sources of drinking water from contamination or overuse. It is the first step to a multi‐barrier approach to protecting municipal drinking water and often is the only line of defence for private drinking water supplies. Source water protection emerged as a result of the public inquiry following the contamination of the Walkerton drinking water supply in 2000.

About 80 per cent of residents in the Cataraqui Source Protection Area, approximately 170,000 people rely on municipal drinking water systems from surface or groundwater sources. The other approximately 40,000 residents in the Cataraqui Source Protection Area obtain their drinking water from private intakes or wells.