The ministry launched the Drinking Water Surveillance Program (DWSP) in 1986, with the participation of 22 municipal drinking water systems in southern Ontario.
Today, more than 100 systems across the province -- representing roughly 80 per cent of the provincial population that is served by municipal systems -- participate in the program.
A map of the DWSP monitoring network shows the monitoring network today and some of the changes it has undergone over time.
Drinking water systems may volunteer to participate in the program. Systems are selected based on:
- geographical location
- population served
- surrounding land uses
- source-water type (e.g. surface water vs. groundwater; lakes vs. rivers)
- type of treatment used
- known issues with unregulated contaminants of concern
Participating drinking water systems are asked for water samples several times each year. Since it began, DWSP has collected more than 4.5 million results from 200 drinking water systems. Sample types include:
- raw water inside treatment facilities prior to being treated
- treated water leaving treatment facilities
- distribution water delivered to the consumer
