ARCHIVED - Fact Sheet - Water Quality

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Drinking Water Advisories

Drinking Water Advisories (DWAs) are preventive measures regularly issued in municipalities and communities across Canada that protect public health from waterborne contaminants that can be present in drinking water.

A DWA can be issued in any community and include boil water advisories, do not consume advisories and do not use advisories.

  • a boil water advisory (BWA) is issued to the public when the water in a community's water system is contaminated with organisms such as e.Coli or when water quality is questionable. Under these circumstances, bringing the water to a rolling boil for at least one minute will render it safe for human consumption.

  • a do not consume advisory (DNCA) is issued to the public when the water in a community's water system contains a contaminant, such as a chemical, that cannot be removed from water by boiling.

  • a do not use advisory (DNUA) is issued when the contaminant that poses a heath risk, such as a chemical spill, cannot be removed from the water by boiling, and exposure to the water could cause skin, eye, and/or nose irritations.

The number of DWAs in First Nation communities across Canada fluctuates, as is the case in other parts of the country, as water quality is not static. Fluctuations can occur for a number of reasons, including: variations in source water quality, repairs or maintenance to water lines, repairs or maintenance to a water treatment system, or new construction. All of these situations require the issuance of a DWA for at least a short period of time as a preventive measure.

The Environmental Health Officer from Health Canada recommends the issuance of a DWA to Chief and Council. It is the responsibility of Chief and Council to issue the DWA in the affected community and it remains in effect until the reason for the advisory has been addressed.

DWAs are also issued by provincial and territorial governments in many small, remote and/or isolated non-First Nation communities across Canada.

Additional information on water quality in First Nation communities and steps to address DWAs is available on the Health Canada  website.

Water Treatment Systems

Water treatment systems are classified according to their level of risk. The difference between high, medium and low-risk water systems depends on what corrective measures are needed to address and resolve the problem.

  • a high-risk drinking water system is a system that has several major deficiencies related to issues such as water source, design, operation, reporting and operator training or certification. Should a problem arise in one of those areas, the system is unlikely to be able to function properly, and there is a high probability that any problem could result in unsafe water.

  • a medium-risk water system is a system with deficiencies which, individually or combined, pose a medium risk to the quality of water and human health. These systems would not generally require immediate action, but should be repaired over time.

  • a low-risk water system is a system that operates with minor deficiencies. Usually, the systems meet the water quality parameters specified by the appropriate Canadian guidelines (notably the Guidelines for Canadian Drinking Water Quality (CGDWQ) for drinking water).

A high-risk system is less likely to be able to cope with problems and thus DWAs may have to be issued more frequently and remain in place for a long time. On the other hand, while low-risk systems may encounter problems, better overall management and the effective use of corrective measures are more likely to address the problem in the short term, resulting in the problem being fixed quickly or a DWA being issued.