Canadian drinking water supplies are generally of excellent quality. However, water in nature is never "pure." It picks up bits and pieces of everything it comes into contact with, including minerals, silt, vegetation, fertilizers, and agricultural runoff. While most of these substances are harmless, some may pose a health risk. To address this risk, Health Canada works with the provincial and territorial governments to develop guidelines that set out the maximum acceptable concentrations of these substances in drinking water. The guidelines set out the basic parameters that every water system should strive to achieve in order to provide the cleanest, safest and most reliable drinking water possible. The Guidelines for Canadian Drinking Water Quality deal with microbiological, chemical and radiological contaminants. They also address concerns with physical characteristics of water, such as taste and odour. (Health Canada, 2017)
Microbiological quality guidelines
The most significant risks to people's health from drinking water come from microscopic organisms such as disease-causing bacteria, protozoa and viruses. The guidelines that relate to these microorganisms are stringent because the associated health effects can be quite severe. They can also affect health over the long-term.
Chemical and radiological quality guidelines
Chemical and radiological substances may also be found in some drinking water supplies but these are generally only a concern if they are present above guideline levels and you are exposed to them over a period of years. New science is showing that exposure to some chemical contaminants above guideline levels may be a concern in the short-term as well.
Aesthetic quality and operational guidelines
Aesthetic quality guidelines address parameters which may affect consumer acceptance of drinking water, such as taste, odour and colour. Operational guidelines are set for parameters that may affect processes at a treatment plant or in the drinking water distribution system. (Government of Canada, 2017)