Safety
Boil water advisory: exactly what to do
Got a boil-water notice? How long to boil, what's safe for brushing teeth, dishes, baby formula and pets, and what to flush when the advisory lifts.
A boil-water advisory (or notice) means your utility can’t guarantee the water is free of disease-causing microbes — often after a main break, a loss of pressure, a treatment problem or a positive bacteria test. It’s usually precautionary, but you should follow it until it’s lifted.
Advisories differ from “do not drink” or “do not use” notices, which are issued for chemical contamination. Boiling does not make chemically contaminated water safe. Read your notice carefully.
How to boil water correctly
- If the water is cloudy, let it settle and draw off the clear water, or filter it through a clean cloth or coffee filter.
- Bring it to a rolling boil for 1 minute. At elevations above 6,500 feet (about 2,000 metres), boil for 3 minutes.
- Let it cool, then store it in clean, covered containers.
- To improve flat taste, pour it between two clean containers a few times.
Electric kettles with automatic shut-off are fine if they reach a full rolling boil.
What’s safe and what isn’t
| Activity | During the advisory |
|---|---|
| Drinking, cooking, coffee, ice | Boiled (then cooled) or bottled water only. Throw out ice made after the problem began. |
| Baby formula | Boiled water cooled to a safe temperature, or bottled water labelled suitable for infants. |
| Brushing teeth | Boiled or bottled water. |
| Washing fruit and vegetables | Boiled or bottled water. |
| Showering and bathing | Generally OK for adults — don’t swallow. Sponge-bathe babies and young children. |
| Washing hands | Soap and tap water is usually fine; use hand sanitiser afterwards if advised. |
| Dishes | A dishwasher with a hot dry cycle or sanitising setting is usually fine. Hand-washing: rinse in water with a small amount of unscented bleach, per your health department’s instructions. |
| Pets | Give pets boiled (cooled) or bottled water. |
Filters during an advisory
Most pitcher, faucet and fridge filters are not designed to remove bacteria and viruses. Unless a product is certified for microbiological reduction (for example NSF/ANSI 55 Class A UV or an equivalent certified purifier), keep boiling.
When the advisory is lifted
- Run all cold water taps for a few minutes, starting at the top floor, until the water runs cold.
- Flush fridge water lines and discard the first three batches of ice.
- Replace filter cartridges that were used with untreated water (fridge, pitcher, under-sink).
- Run water softeners and RO systems through a regeneration or flush per the manufacturer.
- Drain and refill your water heater if your utility recommends it (often only after long advisories).
Who’s most at risk
Infants, older adults, pregnant people and anyone with a weakened immune system should be most careful. If someone develops diarrhoea, vomiting or fever during an advisory, contact a healthcare provider.
Stay informed
Sign up for your utility’s text or email alerts, and follow your local health department. Our daily water news also tracks boil-water advisories.
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