Guidance on the use of Enterococci as an Indicator in Canadian Drinking Water Supplies
This document may be cited as follows:
Health Canada (2020). Guidance on the Use of Enterococci as an Indicator in Canadian Drinking Water Supplies. Water and Air Quality Bureau, Healthy Environments and Consumer Safety Branch, Health Canada, Ottawa, Ontario. (Catalogue No. H144-68/2020E-PDF).
The document was prepared in collaboration with the Federal-Provincial-Territorial Committee on Drinking Water of the Federal-Provincial-Territorial Committee on Health and the Environment.
Any questions or comments on this document may be directed to:
Water and Air Quality Bureau
Healthy Environments and Consumer Safety Branch
269 Laurier Avenue West, Address Locator 4903D
Canada K1A 0K9
Tel.: 1-833-223-1014 (toll free)
Other Guideline Technical Documents for the Guidelines for Canadian Drinking Water Quality can be found on the following web page: www.canada.ca/en/health-canada/services/environmental-workplace-health/reports-publications/water-quality.html
Background on guidance documents
Health Canada works with the provinces, territories and federal agencies to establish the Guidelines for Canadian Drinking Water Quality. Over the years, new methodologies and approaches have led Health Canada, in collaboration with the Federal-Provincial-Territorial Committee on Drinking Water, to develop a new type of document, guidance documents, to provide advice and guidance on issues related to drinking water quality for parameters that do not require a formal guideline under the Guidelines for Canadian Drinking Water Quality.
There are two instances in which the Federal-Provincial-Territorial Committee on Drinking Water may choose to develop a guidance document. The first would be to provide operational or management guidance related to specific drinking water–related issues (e.g., boil water advisories), in which case the document would provide only limited scientific information or health risk assessment. The second instance would be to make health risk assessment information available when a guideline is not deemed necessary.
Guidelines are established under the Guidelines for Canadian Drinking Water Quality specifically for contaminants that meet all of the following criteria:
- exposure to the contaminant could lead to adverse health effects;
- the contaminant is frequently detected, or could be expected to be found, in a large number of drinking water supplies throughout Canada; and
- the contaminant is detected, or could be expected to be detected, at a level that is of possible health significance.
If a contaminant of interest does not meet all these criteria, Health Canada, in collaboration with the Federal-Provincial-Territorial Committee on Drinking Water, may choose not to establish a numerical guideline or develop a guideline technical document. In such a case, a guidance document may be developed.
Guidance documents undergo a similar process as guideline technical documents, including public consultations through the Health Canada website. They are offered as information for drinking water authorities and, in some cases, to provide guidance in spill or other emergency situations.
Enterococci are a bacteriological indicator of fecal contamination. Their presence in drinking water indicates that fecal pathogens may be present which can pose a health risk to consumers. They can be included in a drinking water monitoring program to provide information on the quality of the source water, the adequacy of treatment and the delivery of safe drinking water to the consumer.
Health Canada completed its review of enterococci in drinking water. This guidance document was prepared in collaboration with the Federal-Provincial-Territorial Committee on Drinking Water. It describes the significance, sampling and treatment considerations for the use of enterococci as a bacteriological indicator in the context of drinking water quality and safety.
Under a source-to-tap approach to providing high quality drinking water, enterococci are a complementary indicator of fecal contamination. For jurisdictions considering monitoring in addition to the regulatory requirements, this parameter can supplement existing E. coli and total coliforms monitoring programs, to afford a better understanding of microbiological water quality and inform decision-making. An important advantage of the enterococci group is that they are somewhat more resistant to environmental stresses and drinking water disinfectants than E. coli, although both are readily inactivated by drinking water disinfection. Enterococci may persist longer than E. coli in some water environments. They are therefore useful as a bacterial indicator to provide additional insight into fecal contamination issues in systems suspected of being susceptible to fecal contamination— such as undisinfected groundwater sources and distribution systems—but where E. coli has not been found or is infrequently detected. The intent of this document is to provide stakeholders, such as provincial and territorial regulatory authorities, decision makers, water system owners, laboratories and consultants with guidance on how enterococci can be used in a drinking water monitoring program with the objectives of identifying and minimizing microbiological risks in Canadian water systems.
Drinking water quality guidelines, standards and/or guidance established by foreign governments or international agencies may vary due to the science available at the time of assessment, as well as the utilization of different policies and approaches. Enterococci are widely used for assessing water quality in many parts of the world, but are not used as frequently as other indicators such as E. coli. The World Health Organization and the Australian drinking water authority indicate enterococci can be used to assess source, treated and distributed water quality, but have not established drinking water guideline values. The European Union’s Drinking Water Directive includes enterococci as an audit parameter for monitoring in drinking water distribution systems with a standard of zero enterococci per 100 mL of water and testing requirements that are less frequent than routine monitoring parameters.
The United States Environmental Protection Agency (U.S. EPA) has not established a drinking water guideline value for enterococci. The Ground Water Rule includes enterococci alongside E. coli and coliphages as options when testing for indicators of fecal contamination when total coliforms are detected in untreated ground water systems.
View the Publication: https://www.canada.ca/en/health-canada/services/publications/healthy-living/guidance-use-enterococci-indicator-canadian-drinking-water-supplies.html
Download the PDF version: https://www.canada.ca/content/dam/hc-sc/documents/services/publications/healthy-living/guidance-use-enterococci-indicator-canadian-drinking-water-supplies/enterococci-june-2020-en.pdf