Lead in drinking water mainly comes from the dissolution of lead in pipes, especially connection pipes (service lines) between some houses and the municipal distribution system. Lead service lines were installed in single-family homes and apartment buildings with fewer than 8 dwellings, especially between 1940 and 1955 and even into the ’70s. Welding in the internal plumbing of buildings can also be a source of lead in water.
In Québec, concentration of lead in drinking water may not exceed 0.010 mg/L. Drinking water distribution system officials, including those of municipalities, are responsible for ensuring that this standard is applied.
In general, exposure to lead from drinking water is low and doesn’t cause health problems in adults. Children under 6, including fetuses, are more sensitive to the effects of lead. The effects of exposure to lead over a period of many years are mainly neurobehavioural in nature, such as a decrease in learning ability.
Protection and prevention
Boiling water is useless because lead does not evaporate. In fact, boiling water may increase the concentration of lead in the water.
- Measures to lower the concentration of lead in water and reduce your exposure to it:
- Generally speaking: When water has been resting for a long time, such as when you wake up in the morning or return from work, let it run for one minute or until it is cold before drinking it.
- For drinking or cooking, only use cold tap water. Warm water is more likely to contain lead.
- Regularly remove and clean the aerator (small filter) in the tip of the faucet, because lead can accumulate in it.
- If your house has a lead service line, and if tests reveal there is lead in your water after letting it run 5 minutes: When water has been resting for a long time, in order to avoid drinking the water that has been sitting in the service line, empty the pipe by letting the water run for 5 minutes or by flushing the toilet, taking a shower or doing laundry. Afterwards, you can let the tap water run for about a minute (or until cold) before drinking it.
- You can also use a pitcher water filtration system or install a filter on the faucet or under the sink. These devices must be certified to NSF/ANSI Standard No. 53 for lead reduction. You can buy them at hardware stores and some department stores. Make sure the system remains effective by regularly replacing the filters and following the manufacturer’s maintenance recommendations.
- When the concentration of lead in water exceeds 0.010 mg/L, drinking water distribution-system officials or the regional public health department issue advisories for people directly affected.
For more information on how to reduce lead in drinking water, read Lead in Drinking Water (in French) on the MDDELCC website.
- Foire aux questions: Plomb et eau potable sur le territoire de l’île de Montréal (in French)
Directeur de santé publique de Montréal
Last update: 25 November 2016, 11:19