A boil water advisory means your utility has reason to believe the water may carry microorganisms that can make you ill. It is issued as a precaution and should be treated as binding until lifted.
Why they are issued
Common triggers include a water main break, loss of pressure in the distribution system, equipment failure at the treatment plant, or a bacterial test result that fails. Loss of pressure matters because it can draw contamination into pipes.
What to do
Bring water to a rolling boil for at least one minute, then let it cool. Use boiled or bottled water for drinking, preparing food and drinks, making ice, washing produce, and brushing teeth. Boiled water keeps safely in a covered container in the fridge.
You can generally still shower and bathe, taking care not to swallow water — but follow the specific wording of your advisory, and supervise young children. Handwashing with soap is usually fine.
The part people get wrong
A household water filter does not make water safe during an advisory. Carbon filters, pitchers, faucet mounts and fridge filters are designed for taste, chlorine and chemical contaminants — not for disinfecting microbiologically unsafe water. Running affected water through a filter and drinking it unboiled is not safe.
Two exceptions exist: a reverse osmosis system, or a UV unit, both of which are designed to address microorganisms. Even then, most manufacturers advise boiling during an advisory because the system itself may have been contaminated.
Once it is lifted
Flush your cold taps for several minutes, run and discard a few batches of ice, and change your water filter cartridges. A cartridge that filtered contaminated water should not stay in service.
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