Boil Water Advisories in Canada

Indigenous Services Canada and provincial or municipal health authorities recognize three distinct types of drinking water advisory, and confusing them leads to the wrong response. A boil water advisory is issued when microbiological contamination, disease-causing bacteria, viruses, or protozoa, is suspected or confirmed, and it can be resolved for household use by bringing tap water to a rolling boil for at least one minute before drinking it, brushing teeth, or preparing food or ice. A do not consume advisory is used when a chemical contaminant that boiling cannot remove is present; water under this advisory should not be ingested but can generally still be used for handwashing, bathing, and other non-ingestion purposes. A do not use advisory is the most restrictive category, issued when contact with the water, including through skin or eyes, poses a risk, and it means avoiding tap water for any household purpose until the advisory is lifted. Chemical and radiological advisories (do not consume and do not use combined) are rare, representing roughly 1% of all drinking water advisories issued in Canada; the overwhelming majority are boil water advisories tied to microbiological risk.

Why advisories get issued in the first place

Health Canada's Guidance for Issuing and Rescinding Boil Water Advisories leaves the actual decision to provincial, territorial, and local authorities, who apply a risk assessment specific to the water system and event. Common triggers include a watermain break that lets untreated groundwater or soil intrude into the pipe network, a treatment plant equipment failure (a disinfection system going offline, for example), turbidity spikes after heavy rain that reduce chlorination effectiveness, or a positive test for E. coli or total coliform bacteria in routine monitoring. Advisories can be issued precautionarily, as soon as a risk is identified, without waiting for a confirmed illness outbreak, which is why an active advisory does not necessarily mean anyone has become sick.

Rescinding an advisory follows its own protocol rather than a fixed calendar date. For microbiological advisories, guidance generally calls for at least two consecutive sets of water samples, collected a minimum of 24 hours apart, to return clean results before the advisory is lifted, alongside confirmation that the underlying operational issue, whether a treatment failure or a pipe break, has actually been resolved. That is why some advisories clear within days while others, tied to infrastructure that needs replacing rather than repairing, run for months or years.

First Nations long-term drinking water advisories

First Nations communities track drinking water advisories separately from the municipal and provincial system referenced above, and Indigenous Services Canada (ISC) maintains a specific public commitment around long-term drinking water advisories (LTDWAs), defined as advisories in place for 12 months or longer on public systems funded by ISC. According to ISC's own reporting, 156 long-term advisories were lifted between November 2015 and mid-2026, while 38 remained active across 36 communities as of that period, backed by a $9.4 billion federal commitment toward water and wastewater infrastructure investment. This is a materially different picture from off-reserve municipal advisories, which are typically resolved in days to weeks once the triggering issue (a watermain break, an equipment failure) is fixed; a long-term advisory on a First Nations system generally reflects an underlying infrastructure gap, not a temporary operational event, which is why lifting one is tracked as a discrete capital project rather than a routine maintenance response. ISC publishes an interactive map of lifted and active long-term advisories by community.

What to do during an active advisory

• Check the advisory type first. Boiling is only an effective response to a boil water advisory, not a do not consume or do not use advisory.
• Under a boil water advisory, bring tap water to a rolling boil for at least one minute, then let it cool before drinking, brushing teeth, or using it in food preparation.
• Ice made before an advisory was issued should be discarded, since freezing does not eliminate microbiological contaminants.
• Bottled or otherwise treated water is a reasonable substitute for drinking and food preparation under any advisory type until it is lifted.
• Check your municipality's official notice for the specific advisory type and any additional local guidance, since practical details can vary by jurisdiction.

How this list is built

The table above combines advisories reported through the Government of Canada open data portal, ECCC advisory feeds, and provincial open data where a live connection exists; rows without a confirmed live source are marked as seed placeholders until a provincial feed is wired in. A boil water advisory here is a distinct and materially more urgent signal than a routine hardness or pH reading elsewhere on this topic, and it should always take priority when deciding whether tap water is safe to use at a given moment. For background on how hardness and pH are reported outside of advisory events, see the OpenStats water hardness guide, and for filtration options once an advisory clears, see the filters guide.