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Boil Water Advisory Information

The Ontario provincial government, through the Ministry of the Environment, Conservation and Parks, regulates municipal water systems to ensure water is safe to drink. When the water is no longer safe to drink, a “Boil Water Advisory” is issued by Southwestern Public Health's Medical Officer of Health and the local municipality. 

Frequently asked questions

The water should NOT be used for drinking, making infant formula and juices, cooking, making ice, washing fruits, vegetables or brushing teeth. For these purposes, boiled water or bottled water should be used.

Water should be brought to a rolling boil for at least 1 minute. If there are children in the home, place the pot on the back burner to avoid scalds. Boil only as much water in a pot as you can comfortably lift without spilling.

Discard all ice made previously and disinfect the ice cube trays. Make ice using boiled, cooled water.

Adults and teens may shower with untreated water as long as no water is swallowed.

Older children could also be given a shower with a hand-held showerhead, avoiding the face.

Younger children should be sponge-bathed instead of bathing in a tub because they are likely to swallow tub water.

If the boil water advisory has been issued as a precaution and there is no outbreak of human illness, there is no need for additional hand disinfection with bleach solution or alcohol using the measures described below.

If the boil water advisory has been issued because of an outbreak, water can be used for hand-washing after the following emergency water treatment:

  • Mix 1.5 oz (45 ml) liquid household bleach with 10 gallons (45 litres) water.
  • Mix and let stand for at least 10 minutes prior to use.

You can use alcohol-based hand disinfectants, containing more than 60% alcohol. These products are widely used in the health care setting after washing hands or in situations when water is not available.  

The wet wipes used for cleaning babies during diaper changes are not effective for disinfecting hands and should not be used for this purpose.

If your dishwasher has a hot setting, it safely disinfects dishes.

If your dishwasher does not have a hot setting, after finishing the cycle, soak dishes for 1 minute in a solution of 1 oz. (30 ml) of bleach mixed with 3 gallons (13.5 litres) of lukewarm water. Let dishes air dry.

You could use boiled water for washing dishes.

Dishes washed in soap and hot water can also be rinsed in boiled water or disinfected with the following bleach solution:

  • Mix 1 oz. (30 ml) bleach with 3 gallons (13.5 litres) of water at room temperature for at least 1 minute
  • Let dishes air dry.

No, continue doing laundry the way you usually do.

If you have to launder sheets heavily soiled with feces, carefully remove soil before you place the sheets into the washer, without much agitation of the cloth. Use rubber gloves when handling heavily soiled sheets.

No, the water is not safe to use in wading pools. Water may get into the mouths of small children, providing a possibility for infection.

No. Filtered water should also be brought to a rolling boil for 1 minute before drinking or using it for cooking.  

Dental offices should not be using water that is plumbed into the dental operatory

Always follow your physician’s and dietitian’s advice. You might be advised to use bottled water or to boil water for drinking/cooking, even in the absence of a boil-water advisory.

The Ontario Drinking Water Quality Standards (ODWQS) state that the Medical Officer of Health should continue the boil water advisory until the standards in the ODWQS are no longer exceeded in two consecutive sets of samples taken from all parts of the distribution system that has been affected. The standards address issues that can affect health, such as the presence of E. coli. The Medical Officer of Health may choose not to lift the boil water advisory even if two acceptable samples are obtained.

  • Run cold water faucets for 1 minute before using the water.
  • Run drinking fountains for 1 minute before using the water.
  • Flush all garden hoses by running cold water through them for 1 minute.
  • Run water softeners through a regeneration cycle.
  • Drain and refill hot water heaters set below 45°C (normal setting is 60°C).

Please contact your local veterinarian for guidelines and more information.

Drinking Water Advisories

Drinking Water Advisories are issued by the Medical Officer of Health to advise residents to use an alternate water source, such as bottled water. A Drinking Water Advisory is a safety measure issued to protect the public as the water source is not safe for drinking or other uses. A Drinking Water Advisory would be issued during situations when boiling the water will not get rid of the problem, such as a chemical contamination.  

Contact Us

Southwestern Public Health (8:30 a.m. - 4:30 p.m., Monday - Friday)

St. Thomas Site
(Administrative office)
1230 Talbot Street
St. Thomas, ON N5P 1G9

Woodstock Site
410 Buller Street
Woodstock, ON N4S 4N2

Call us toll free: 1-800-922-0096
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