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Ministère de la Sécurité publique

What Should You Do After Heavy Rains or Floods?

After such disasters, it is essential to take certain precautions.

The purpose of this pamphlet is to offer you helpful advice and give you instructions for cleaning your residence. It is important to protect the occupants' health and prevent further damage to your home and its contents. You will also learn how to eliminate debris left by floodwater and how to obtain financial assistance.

In case of doubt, do not hesitate to contact your municipality for clarifications or any other useful information.


Avoid any contact between extension cords and water. Before restoring the power, have the electrical installation and heating equipment inspected by specialists, if this has not already been done, to prevent damage or avoid injuring yourself by inspecting them personally.


Avoid touching your face with your hands or gloves after handling soiled objects. Take care to wash your hands thoroughly.

If, despite all these precautions, you show symptoms of persistent diarrhea or severe indigestion, consult your family physician without delay.

For information and advice concerning health, you can contact your local Info-Santé CLSC service.

If you have any psychosocial needs related to the recent floods, do not hesitate to obtain information from the CLSC in your territory (in French).

For Quality Drinking Water

Water from the Water Main

If you suspect that water intended for consumption is contaminated because of its taste, colour or odour, purify it by boiling it for at least one minute. The municipality normally should send you a warning to boil drinking water in case of microbial contamination.

Well water

Water from individual well may be contaminated after a flood and is therefore considered undrinkable until proof to the contrary.

Here are the precautions to take to disinfect an individual artesian or surface well properly:

  • Scrape the well clean - that is, remove foreign bodies, deposits and animal or vegetable matter with a brush or a scraper.
  • Pour the required quantity of Javel water into the well. (See the table further.)

Javel water solutions available on the market can all be used immediately. If is sufficient to use the required quantity for effective disinfection and follow these steps:

  • Mix the Javel water with the well water. Wash and brush the side wall with this mixture. If this is impossible, connect your garden hose to the valve and wash the well's inner wall. For optimum effectiveness, allow the mixture to act for about one hour without using the well water.
  • Next, open all the taps and flush the toilets. When the odour of chlorine becomes perceptible at each outlet, close the taps. Otherwise, add more Javel water in the well.
  • Let the well sit for 24 hours, using the toilets, the bathtub and the washing machine as little as possible. Be careful not to drink the water.
  • After 24 hours, let the water run from all the taps until the chlorine odour dissipates. Use the water abundantly for 2 or 3 days (washing, cleaning, toilets).
  • At the end of this process, the water must be analyzed to determine whether it meets the standards of the Regulation respecting the quality of drinking water. If the results do not conform after two disinfections, contact a well expert and have your well inspected.


Do not drain the well. If you have a septic bed, run the water from a tap located outside so that you do not overload your septic system.

Table of Javel water volumes required
Type of well

Diameter in centimetres

Diameter in  inches

Millilitres of Javel water required per metre of depth

Ounces of Javel water required per 
foot of depth




20 ml

1/4 oz




35 ml

1/2 oz




300 ml

3 oz




625 ml

6 oz

To determine the quantity of Javel water to be added to your well, multiply the depth of your well (in metres or feet) by the volume of Javel water required (see the table), depending on the diameter of your well (artesian or surface).

Example in feet

What volume of Javel water would be necessary to disinfect an artesian well 65 ft. deep with a diameter of 6 in.?


65 ft. x 1/4 oz. / ft. = 16 1/4 oz. of Javel water to be added.

Example in metres

What volume of Javel water would be necessary to disinfect an artesian well 20 m deep with a diameter of 15 cm?


20 m x 20 ml / m = 400 ml of Javel water to be added.

Watercourses and Debris

To repair damage to watercourses

Floods cause major damage to watercourses. You must obtain prior authorization from your municipality to perform the work necessary to regularize the situation.

To eliminate debris left by floodwater

Floodwater brings debris, such as solid waste and other materials. Solid waste must be sent to a sanitary landfill site. Other types of waste (tires, hazardous materials, etc.) must be sent to a site authorized to receive this type of waste.

For more information

Call your regional office of the ministère du Développement durable, de l'Environnement et des Parcs (in French).

What to throw out?

  • All food, drugs, toiletries and beauty products that have been in direct contact with floodwater.
  • Mattresses, box springs, pillows and furniture when the upholstery has been waterlogged. These articles cannot be thoroughly cleaned. Dry cleaning will only clean the surface of the fabrics, but the inside will remain contaminated.
  • Carpets and rugs, because it is almost impossible for you to dry large areas of waterlogged carpeting quickly on your own. 
  • All waterlogged materials, as soon as possible, because they foster the growth of moulds, which could cause serious health problems.
  • Wet wool insulation, because this wool will never again be good insulation and could foster the growth of moulds. Check the walls up to 50 centimetres or 20 inches above the waterline. Open up any walls that have absorbed water.
  • Replace the insulation inside the water heater, the refrigerator and the freezer if it was waterlogged.


  • Throw out all foodstuffs, whether perishable or not, found inside the house or buildings, if it has been in contact with floodwater.
  • In the case of flooded vegetable gardens, throw out all fruits or vegetables that are ready for consumption and growing out of the soil, such as strawberries and lettuce. You can keep all underground crops, because they are peeled before consumption, particularly potatoes and carrots. Take care to clean them well before preparing them.

Home cleaning and disinfection

  • After a flood, you must take precautions to ensure that objects, furniture and the dwelling itself are not contaminated.
  • To avoid contamination, proceed with drying as quickly as possible. Once this is completed, you must first determine what has to be thrown out and then what will be cleaned and disinfected. If you keep soiled objects or materials, you run a longer-term risk of aggravating contamination of the dwelling and causing health problems for the occupants. 
  • For cleaning, wear rubber gloves to avoid any contact with the water and soiled materials, because there is a high risk of infection. Even after these surfaces are well dried, they may contain bacteria and cause infections. Be doubly cautious in the case of sewage flooding.
  • Wash and clean all floors.
  • Clean and disinfect all surfaces, as well as the interior cavities and the structures that were in contact with floodwater. Ensure that the area is well ventilated.

Cleaning solution

One part Javel water diluted in four parts water, to which you will have added a small quantity of ammonia-free dishwashing soap. Never mix Javel water with ammonia, because the vapours released are toxic.

Humidity conditions

Ventilate and dehumidify the home to reduce and maintain the humidity rate at under 50%.

Financial Assistance to Disaster Victims

See if you are eligible to financial assistance to disaster victims.

Dernière mise à jour : 28 mars 2008