Drinking water contamination or shortage

Water is a vital resource for human beings. It must be of impeccable quality and available in sufficient quantity. Contaminated drinking water or water shortages may arise under various circumstances, for example, the bursting or freezing of a water main, a drought, a flood, or the presence of chemical products, pests or cyanobacteria (blue-green algae) in the water.

In Québec, heads of drinking water distribution systems must ensure the high quality of the drinking water in their network. This is why they periodically collect water samples to make sure that the water meets certain standards (in French only) and then take corrective action if necessary.

If the water in your home comes from a private well, you must take the following precautions:

  • ​Have your well water analyzed regularly.
  • Disinfect it if need to be.

In the event of a drinking water shortage or contamination, a number of provisions must be taken pending a return to normalcy:

Be prepared

Keep bottles of drinking water on hand at home. Calculate at least two litres per person per day and have enough for at least three days.

Follow the authorities’ instructions

If there is a problem regarding water quality or availability, the authorities will provide instructions. Follow them carefully. If your municipality organizes a drinking water distribution initiative or encourages you to get your water in a place that is not affected by the problem, consult it for instructions regarding how the water is to be distributed and used.

Even if you are not affected by a water quality or availability issue in your municipality, you might receive an advisory regarding water use restrictions. For example, a notice may prohibit watering lawns, trees or flowers, filling swimming pools or washing vehicles for a specified period. Regardless of the restriction in question, you must strictly observe the instructions provided to prevent a possible water shortage or ensure the situation returns to normal as soon as possible for everyone in your municipality.

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Know what to do in the event of drinking water contamination

In the event of drinking water contamination, follow boiling or drinking water avoidance advisories issued by the heads of drinking water distribution networks. Even clear, odorless and tasteless, water can pose a health risk.

When a boiling or drinking water avoidance advisory is issued, schools, businesses, stores and institutions are requested to close any water fountains and notify their clientele and visitors that the water is unfit for consumption. Food establishment operators must adopt specific precautionary measures (PDF, 3,85 MB, in French only).

In the workplace, the employer must provide all staff with access to safe drinking water.

Instructions when a boil water advisory is issued

In the event of a boil water advisory, boil tap water at least one minute at a rolling boil before drinking it. Also use boiled water to:

  • Prepare infant formula, feeding bottles and baby food
  • Prepare drinks, juices, tea and coffee
  • Wash fruits and vegetables eaten raw
  • Prepare foods that do not require prolonged cooking (canned soups, jelly, etc.)
  • Make ice cubes
  • Brush your teeth and rinse your mouth
  • Provide drinking water for pets such as dogs, cats, birds and reptiles. Let the water cool down sufficiently before giving it to them.

Boiled water can be stored for up to 3 days in the refrigerator in sealed and clean containers, or for 24 hours at room temperature. Handle the boiling water carefully to avoid the risk of burns; this warning is especially important for young children and the elderly.

If you have a domestic water filter (softener, activated carbon system, filtering pitcher, etc.), you still must boil the water before drinking it. These types of water treatments are not designed to kill all micro-organisms that may be harmful to health.

However, if you have a water purifier, for instance using chloride, ozone or ultraviolet rays, it is not necessary to boil water provided that the device complies with standards (in French only)and is well maintained and in good working order. If in doubt, check with the manufacturer.

If there is a boil water advisory and unless otherwise notified, you can use tap water directly in the following cases:

  • For food preparation and for cooking dishes which require prolonged boiling, for example, soups, pasta and vegetables (potatoes, beans, etc.)
  • For personal hygiene and all domestic purposes, for example
    • Washing your hands, provided you use soap, rinse thoroughly and dry immediately
    • Taking a bath or shower, provided you do not swallow any water. It is best to scrub young children and infants with a washcloth to prevent them from swallowing water or putting toys in their mouths that have been in contact with water.
    • Washing the dishes with detergent, provided you ensure that they are completely dry before using them. If you have a dishwasher, using the hottest cycle ensures that the water is disinfected.
    • Washing clothes
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Instructions when a drinking water avoidance advisory is issued

In the event of a drinking water avoidance advisory, use only bottled water or water from another drinking water source. In general, tap water can only be used for domestic purposes, such as for laundry or dishes, and for personal hygiene, unless otherwise specified in the notice. In some cases, there may be restrictions on the use of water for personal hygiene depending on the existing contaminants and their concentration.

Even if you have a home water treatment device, you must only consume bottled water or drinking water from another source. These devices do not necessarily provide effective protection against existing contaminants.

Instructions when a “do not use” advisory is issued

If a “do not use” advisory has been issued for your municipality, do not use your tap water in any circumstances, even if it has been boiled. Instead, you must use bottled water or water from another source of drinking water for all food-related uses. For personal hygiene and household uses, like cleaning surfaces, use only replacement water supplied by authorities or water from another source that is appropriate for such uses. Pay close attention to the information provided in the advisory on how to procure water. Avoid using water from your municipal water system, except to flush your toilet.

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Know the health consequences

The ingestion of contaminated water can cause various symptoms, such as nausea, vomiting, diarrhea or abdominal discomfort. A person may also experience no symptoms whatsoever. If you are experiencing symptoms, you can contact the Info-Santé service by dialing 811.

Anyone can be affected by contaminated water. However, infants, young children, pregnant women, the elderly, people with weakened immune systems and those suffering from chronic diseases are generally most likely to be affected. It is therefore recommended to pay special attention to these people.

Know what to do after a boil water or drinking water avoidance advisory is lifted

When test results show that the water being supplied is again in compliance with standards and no longer poses a risk to users’ health, the boiling or drinking water avoidance advisory may be lifted by the head of the distribution network.

Once an advisory is lifted, you are advised to take the following precautions:

  • Open all cold water taps and let the water run for a few minutes before using it, to enable the complete emptying of all piping. Follow the same procedure for drinking fountains and drinking troughs.
  • Empty, wash and disinfect ice machines.
  • Flush out garden hoses and outdoor taps.

However, it is not necessary to drain a hot water tank.

Once a boil water or drinking water avoidance advisory is lifted, you must refer to the manufacturer’s recommendations for the upkeep of your water treatment device.

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Take precautions after a flood

During a flood, take precautions before consuming or using your water.

If your home water comes from a drinking water distribution system

During or after a flood, if your home water is obtained from a drinking water distribution system, it is drinkable, i.e. fit for consumption, unless the municipal authorities in charge of the system inform you otherwise. You can drink it or use it to prepare meals or brush your teeth, for example.

If in doubt as to the colour, odour or taste of your water, contact the municipal authorities before drinking it.

If your home water comes from a private well

During or after a flood, if your home water is obtained from a private well, the water must be considered undrinkable, i.e. unfit for consumption, even if it looks clear and odorless.

Until you are certain that your well water is up to standards, bring the water to a rolling boil for one minute before consuming it, or use bottled water.

Disinfect your well and have your well water tested

Wait at least ten days after the flood water has completely receded before disinfecting your well and having your water tested. Only water which meets drinking water quality standards is considered safe for consumption. Only water which meets drinking water quality standards is considered safe for consumption.

For more information on drinking water quality standards, contact the Ministère du Développement durable, de l’Environnement et de la Lutte contre les changements climatiques by telephone at 1-800-561-1616, or by email at info@mddelcc.gouv.qc.ca.

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