Total Coliform Standard and
Corrective Actions

After the Council’s review of the Drinking-Water Systems Regulation (O. Reg. 170/03) in 2004, the Council continued to hear from stakeholders concerned that the Total Coliform Standard was too stringent, or had been changed to be more stringent.  It is therefore believed that there is some confusion around the numerical Standard versus the level for which Corrective Actions are taken, and by whom.

The only Standard for Total Coliforms in Ontario is “Not Detectable”, as prescribed, since 2003, in the Ontario Drinking-Water Quality Standards Regulation (O. Reg. 169/03). Previously, O. Reg. 459/00 identified any detection of coliform bacteria in drinking water as an indicator of adverse water quality. Prior to that, there was a Drinking Water Quality Objective for Total Coliforms, which was also “Not detectable”.

Corrective Actions are either prescribed by regulation under the Safe Drinking Water Act, or administered by Public Health Inspectors, under the Health Protection and Promotion Act.

Under the Safe Drinking Water Act, both the Drinking-Water Systems Regulation (O. Reg. 170/03) and the Non-Residential and Non-Municipal Seasonal Residential Systems That Do Not Serve The Public Regulation (O. Reg 252/05) prescribe Corrective Actions to be taken when any positive Total Coliform results are discovered.

It is understood by the Council that a new Regulation, replacing O. Reg 252/05, is being developed for promulgation under the Health Protection and Promotion Act. At that time, Total Coliform Corrective Actions will be determined by Public Health Inspectors, using a mandatory Risk-Based Site-Specific Assessment for all subject facilities.

Private systems and systems that do not serve the public are currently unregulated. However, Total Coliform Corrective Actions (and their trigger level) may be recommended by Public Health Inspectors, and could also be subject to a Risk-Based Site-Specific process in the future.

Total Coliforms include a large number of non-disease-causing bacteria arising from soil and vegetation. Their presence, as long as no E. coli is detected, indicates system vulnerability and a potential pathway for pathogens, but does not necessarily require immediate implementation of Corrective Actions such as Boil Water Advisories or the use of alternative drinking water sources. However, the Council believes that investigation into the cause (s) of the presence of Total Coliforms should be undertaken by Public Health Inspectors, as part of a Risk-Based Site-Specific Assessment process.

The Council transmitted its final advice letter to the Minister of the Environment on this issue on June 1, 2006.

Click here to view the Council's advice.