The Drinking Water Surveillance Program ( DWSP ) is a voluntary program operated by the Ministry of the Environment ( MOE ) in cooperation with municipalities to gather scientific data on drinking water quality in Ontario. From 2000 to the end of 2002, 179 municipal drinking-water systems were collecting samples for the program. Laboratory analyses are provided by the MOE and the Ministry of Labour.

Summaries and detailed reports for the 179 municipal drinking-water systems that were monitored from 2000 to 2002 are provided on this web site as part of the Ontario government's commitment to make information about drinking water readily available to the public. Results showed that 99.8 percent of the tests performed for chemical, physical and radiological parameters in treated drinking water and water in the distribution systems indicated non-adverse water quality conditions. Tests for microbiological organisms, such as Escherichia coli ( E. coli ), are performed routinely by each drinking-water system and were not monitored by the DWSP .

Over 555,300 inorganic, organic and radiological tests were performed on raw water, treated drinking water and water in the distribution systems. Of the over 121,700 tests for chemical, physical and radiological parameters in treated drinking water and water in the distribution systems, over 121,500 test results met the health-related Ontario Drinking Water Objectives / Standards. One hundred and ninety test results exceeded a health-related objective / standard. The health-related objective / standard for atrazine plus N-dealkylated metabolites, chloramines, fluoride, lead, N-nitrosodimethylamine (N D M A), nitrates, selenium, total trihalomethanes, and turbidity were exceeded on at least one occasion at 35 municipal drinking-water systems for the 2000 to 2002 monitoring period. In addition, of the 3,950 tests reported for free and combined chlorine residuals, over 3,930 test results were above the minimum criteria for disinfectant residuals. Sixteen test results, at 9 municipal drinking-water systems, were below the minimum criteria for disinfectant residuals resulting in adverse water quality. For more information on these parameters, see the DWSP parameter groups section of this report.