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It is the goal of the Region of Durham to provide its residents with high quality, safe drinking water. To achieve this goal the Works and Health Departments of the Region of Durham conduct an extensive bacteriological surveillance program. The program monitors and evaluates water quality throughout the community to ensure that the municipal water supplies are maintained and operated in accordance with current Ontario Drinking Water Objectives.

What are Coliforms?

Coliform are a group of indicator bacteria used to assess the bacteriological quality of drinking water. Coliforms are not necessarily harmful but their occurrence in water may indicate the presence of other pathogenic organisms. Testing for Coliform bacteria has been adopted world wide as the best way to determine whether drinking water is safe for human consumption because:

What is E. coli?

E. coli bacteria are normally harmless inhabitants of the intestines of humans and animals. Water supplies may become contaminated through contact with the faeces of animals or humans. The presence of E. coli in drinking water is a definitive indicator of recent fecal pollution and therefore poses a potential health risk.

How can bacteria enter into the municipal water system?

Contamination of municipal drinking water by Coliforms and/or E. coli may result during construction of distribution lines, main breaks or possible cross-connections in a given water system.

Health concerns associated with contaminated drinking water

Contaminated drinking water poses a health risk to the public. Municipal drinking water is routinely analyzed for the presence of two specific groups of indicator organisms, Total Coliforms and Escherichia coli (E. coli). The Ontario Drinking Water Objectives require that Total Coliform levels are maintained at zero (0) colonies per 100 ml (of water) and E. coli at zero (0) colonies per 100 ml (of water). This objective has been set as an indicator of adequate disinfection within the distribution systems associated with a water works. Elevated levels of these bacteria in water may cause a variety of health effects. Symptoms of E. coli illness include watery diarrhea, abdominal pain, nausea and vomiting. If you suspect that you may be infected with this organism it is advisable to consult your family physician immediately.

What is being done to ensure that your water is safe to drink?

All drinking water in the Region of Durham is disinfected using chlorine and is continually monitored. Most pathogenic bacteria are killed by chlorine used to disinfect municipal water. Extensive bacteriological monitoring is conducted by the Durham Region Works Department at local treatment plants and distribution systems, and by the Durham Region Health Department throughout the community to ensure that the municipal water supply is maintained and operated in accordance with the Ontario Drinking Water Objectives.

In the event that the Regional Works Department identifies a contamination problem with the municipal water supply that may lead to a potential health risk, the Health Department would immediately be notified and steps would be taken to notify the public.

More information can be obtained from

Durham Region Health Department, Environmental Help Line 905-723-3818 or 1-888-777-9613

April 22, 2013