Skip to content

Health Topics & Programs - Boil Water Advisory

What are the reasons for a boil water advisory?

There are different reasons for issuing a boil water advisory.

1. A boil water advisory can be based on bacterial (microbial) examination, including the finding of bacteria or parasites.

2. A boil water advisory can be based on information other than bacteriological examination indicating that the water may not be safe to drink (for example, the lack or absence of disinfection residual [chlorine] in the drinking water).

3. A boil water advisory can follow the occurrence of an outbreak of illness in the community that has been linked to consumption of the water.

The extent of restriction on water use depends on the situation and the reason for issuing the boil water advisory. Always follow your health unit’s recommendations on water use.

How do I use water when a boil water advisory has been issued?

Important: The water should not be used for drinking, making infant formula and juices, cooking, making ice, washing fruit and vegetables, or brushing teeth, for these purposes, boiled water should be used.

The water should be brought to a rapid rolling boil and boiled for 1 minute. If there are children in the home, place the pot on the back burner to avoid scalds. Discard all ice made previously and disinfect the ice cube trays. Make ice using boiled, cooled water. Alternatively, bottled water or potable water from another source can be used for these purposes.

I have a water filtration device installed. Does this make the water safe drinking or cooking?

No. Filtered water should be brought to a rolling boil for 1 minute before drinking or using it for cooking. Filters which have come into contact with water affected by a boil water advisory should be replaced or disinfected following manufacturer’s instructions.

Are babies receiving breastmilk at risk?

Continue to breastfeed your child. If a mother has been drinking unboiled water that may have been affected, it is only in very rare circumstances that breastmilk may be contaminated. If there is an issue, the Health Unit will notify local residents through media channels.

Are babies receiving infant formula at risk?

Infant formula should be used after making an informed decision. During the advisory tap water boiled for at least 1 minute can be used to prepare formula. As an additional level of protection, water from an alternate source, such as bottled water could be used.

Can I use the water for handwashing?

Hands should be washed using boiled, cooled water. Alternatively, you can use alcohol-based hand sanitizers, 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. If hands are not visibly soiled alcohol-based hand sanitizers alone are sufficient.

However if the hands are visibly soiled regular water or a pre-moistened towelette, such as those used for cleaning babies during a diaper change, can be used to remove the dirt then use the alcohol-based hand sanitizer to kill bacteria.

Can I take a bath or a shower?

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.

Can I disinfect toys handled by a child who has been ill with diarrhea?

Use rubber gloves when handling heavily soiled toys. If the toys are visibly soiled, wash them first with soap and water and then disinfect with a freshly prepared bleach solution (1/4 cup (about 60 ml) bleach in to 1 gallon (4.5 litres) of water). Dip toys in to this solution and air-dry them. Cloth and plush toys could be washed or dry-cleaned.

Is it safe to use a dishwasher?

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 50 ml of bleach mixed with 5L of lukewarm water. Let dishes air dry.

How do I disinfect my dishes during a boil water advisory if I wash them by hand?

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 of 50 ml of bleach mixed with 5L of lukewarm water and soak dishes for 1 minute. Let dishes air dry.

How do I disinfect counter tops, chopping boards, or utensils which have come into contact with raw meat during a BWA?

Counter tops, chopping boards or utensils which have come into contact with raw meat should be washed with soap and hot water first, then disinfected with a bleach solution of 100 ml of bleach mixed with 5L of lukewarm water. Do not reuse or store this solution, but make it fresh daily.

How can I disinfect a container for storing drinking water during a BWA?

Use a container that has only been used for water or food. Clean the container with hot soapy water. Rinse the container with boiled water or water from an alternate source not affected by the BWA. To disinfect your container, mix 50 ml of household bleach with 5L of boiled water or water from an alternate source not affected by the BWA. Shake the container for at least 1 minute. Use the same solution to disinfect the cap, lid, and mouth of the container. Empty the container and let air dry. Replace the lid.

Should I change the way I do laundry during a boil water advisory?

No, continue doing laundry the way you usually do. If you have to launder sheets heavily soiled with feces, carefully remove any soil before you place the sheets into the washer, without much agitation of the cloth. Use rubber gloves when handling heavily soiled sheets.

Is the water safe to fill wading pools for children during a BWA?

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

What should I do during a BWA if my doctor has told me that I am immunocompromised?

Always follow the advice of your health care provider or dietitian. You might be advised to use water from an alternate source, even when a drinking water advisory has not been issued.

What should I do after the BWA is lifted?

- 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

- replace carbon filters as these may harbour bacteria

- drain and refill hot water heaters set below 45ºC (normal setting is 60ºC)