Bricareau Water Specialist
Water contaminants
Water quality

Understanding
water contaminants

Learn about the most common pollutants in Québec drinking water and how our systems can protect you from them.

Explore the contaminants

Why test and filterthe water in your home?

The water that flows from your taps, whether from a private well or a municipal network, travels a long way before it reaches you. Along the way, it can pick up a range of unwanted elements. Understanding what is in your water is the first step toward truly healthy, safe hydration for your family.

Invisible to the naked eye

Perfectly clear water can hide dissolved minerals, chemicals or imperceptible micro-organisms.

Impact on health

Some pollutants, such as lead or bacteria, build up or act quickly, affecting your family's well-being.

Strict standards

Health Canada sets strict limits (MACs) to ensure that distributed water remains safe to drink.

Guide to the mainwater contaminants

Explore the most common pollutants, sorted by category, to understand where they come from and their impact.

Metals and heavy metals

13 items

Lead

Often leaches from old pipes and solder. Toxic even at low doses, and particularly dangerous for children's neurological development.

Arsenic

Naturally present in some rocks, it can contaminate well water. It is a known carcinogen with serious long-term health effects.

Mercury

A highly toxic heavy metal, often from industrial discharges or natural processes. Can cause serious damage to the nervous system and kidneys.

Iron and manganese

Very common in wells. Although of little danger to health, they cause stubborn stains (rust, black), cloudy water and an unpleasant metallic taste.

Copper

Usually comes from the corrosion of copper pipes. Can cause gastrointestinal problems and damage the liver at high doses.

Barium

A natural element sometimes found in groundwater. Prolonged exposure can lead to cardiovascular problems and higher blood pressure.

Guidelines fromHealth Canada

See the complete list of Guidelines for Canadian Drinking Water Quality, including microbiological, chemical and radiological parameters.

Contaminant Guideline Common sources Health considerations
Total coliforms (2020) MAC of none detectable per 100 mL in water leaving a treatment plant and in non-disinfected groundwater leaving the well Human and animal feces; naturally present in water, soil and vegetation Total coliforms are not used as indicators of potential health effects from pathogenic micro-organisms; they are used as a tool to determine the effectiveness of the water treatment system and to indicate changes in water quality in the distribution system.
Escherichia coli (E. coli) (2020) MAC: none detectable per 100 mL Human and animal feces E. coli is an indicator of fecal contamination used as a tool to verify drinking water quality. Its detection indicates recent fecal contamination and that micro-organisms capable of causing gastrointestinal illness may also be present. Pathogens in human and animal feces pose the greatest immediate danger to public health.
Enteric protozoa: Giardia and Cryptosporidium (2019) Water Talk – Enteric protozoa (Giardia and Cryptosporidium) in drinking water Treatment goal: removal and/or inactivation of at least 3 log of cysts and oocysts Human and animal feces Giardia and Cryptosporidium are generally associated with gastrointestinal illness (nausea, vomiting, diarrhea). Less common health effects vary. Giardia infections can include long-lasting gastrointestinal upset, malaise and malabsorption. In immunodeficient individuals, Cryptosporidium infections can have effects outside the gastrointestinal tract, including in the lungs, middle ear and pancreas.
Turbidity (2012) Treatment limits for water from individual filters or units: conventional or direct filtration: ≤ 0.3 NTU; slow sand or diatomaceous earth filtration: ≤ 1.0 NTU; membrane filtration: ≤ 0.1 NTU Naturally occurring particles: inorganic matter (clay, silt, metal precipitates); organic matter (decomposed plant and animal debris, micro-organisms) Particles can harbour micro-organisms, shielding them from disinfection, and trap heavy metals and biocides; high or changing turbidity in filtered water can indicate a problem in the treatment process and a possible increased risk of pathogens in the treated water.
Enteric viruses (2019) Water Talk – Enteric viruses in drinking water Treatment goal: reduction (removal or inactivation) of at least 4 log Human feces Generally associated with gastrointestinal illness (nausea, vomiting, diarrhea); less common health effects can include respiratory symptoms, central nervous system infections, liver infections and muscular syndromes.