What to Do During a Boil Water Advisory
A boil-water advisory means officials believe microbes may be in the tap water. CDC’s boil-water toolkit says to use a rolling boil for 1 minute (3 minutes above 6,500 feet). Use boiled or bottled water for drinking, cooking, brushing teeth, and washing dishes that will touch food until the advisory is lifted. If the notice is about chemicals, boiling will not fix the problem.
Boil-water notices are common after main breaks, floods, and long outages that disturb treatment plants. They are not the same as a “do not use” chemical notice. Read the actual language from your utility or health department.
How to boil, store, and use the water
Fill a pot with the tap water, bring it to a rolling boil for the CDC time that matches your elevation, cool it, and keep it in clean covered containers.
Some water will evaporate. Improve flat taste by pouring between two clean containers. If you cannot boil, CDC and EPA describe household-bleach disinfection for microbial risk on otherwise drinkable water. Use the dose table in making water safe - 8 drops of 6% unscented bleach per gallon (EPA), or 6 drops of 8.25% bleach per gallon, then wait 30 minutes.
Handwashing still matters. If officials say the tap is unsafe even for washing, use bottled or boiled water, or soap and a safe source, and use sanitizer as a backup when water is scarce.
When boiling is the wrong tool
Do not boil floodwater or water with a fuel or chemical odor, and do not boil water that officials have declared chemically contaminated.
Find another source or wait for official distribution. Filters and SODIS also do not remove many chemicals. After an advisory is lifted, follow the utility’s instructions for flushing pipes and replacing ice. The EPA Safe Drinking Water Hotline is 1-800-426-4791.
What household tasks require safe water during an advisory
Until officials lift the notice, use boiled or bottled water for drinking, making ice, washing raw foods, preparing formula, brushing teeth, and rinsing dishes that will touch food, unless your local notice says something stricter.
CDC’s boil-water toolkit is written for utilities and for the public, and it is the backbone of this page. A local notice always wins if it is stricter. Some notices say you may wash hands with tap water and soap; others tell you to use bottled or boiled water even for handwashing. Read the words you were given.
Ice already in the freezer was made before the advisory only if you are sure of the timing. When in doubt, discard ice and make new ice from safe water after the advisory ends and you have flushed the ice maker as the utility directs. Pets should receive the same boiled or bottled water you would drink.
Dishwashing: if the notice allows dishwashing with precautions, follow those precautions (often including a sanitizing step). If you are not sure, wash in boiled, cooled water or use disposable dishes for a short advisory. Hand sanitizer is a backup when soap and safe water are scarce; it does not remove heavy dirt and is not a reason to skip washing when washing is possible.
Bathing is often still allowed with a caution not to swallow water, especially for adults; infants and people with weakened immune systems may need a more careful approach. Again, the local notice wins. Do not use chemically contaminated water for bathing if officials have issued a “do not use” order rather than a boil-water advisory.
How a boil-water notice is different from a long blackout water plan
An advisory means the utility believes microbes may be in the pipes. A long outage may add a lost pump, a dry tap, and the need to treat water you find elsewhere. The methods overlap, but the starting point is different.
If the tap still runs during an advisory, you have a convenient source that only needs the official microbial treatment, usually boiling. That is simpler than hauling creek water. If the tap is dry, you are in the broader situation described in making any water safe to drink and in how much water to store.
After officials lift an advisory they often tell you to run cold-water faucets for several minutes, flush the refrigerator ice maker, and replace refrigerator filters if you use them. Follow the utility’s flush times rather than a guess from a neighbor.
Chemical contamination - fuel in the lines, certain industrial spills - is a different order. Boiling can concentrate some chemicals. Do not boil that water. Do not bleach it and call it done. Use bottled water or an official distribution site, and call the EPA Safe Drinking Water Hotline at 1-800-426-4791 if you need help finding the right agency.
Hurricanes and other storms in the Southeast and Gulf frequently produce boil-water notices after pressure drops in the pipes. The Florida and Texas editions of 90 Days Without Power mention that pattern without inventing counts. See Florida and Texas.
Keep a pot you are willing to use only for water, a lid, and a way to heat it outdoors if indoor cooking is unsafe. A camp stove used outdoors, never as an indoor heater, can boil water when the electric range is dead. Carbon monoxide rules still apply.
A kitchen setup that makes the next notice easier
Keep a pot with a lid, a way to time a rolling boil, clean bottles, and the EPA bleach figures written on a card so you are not searching official pages on a dying phone.
Write both boil times on that card: 1 minute at lower elevations and 3 minutes above 6,500 feet (CDC), plus this book’s conservative 3-minute household rule at or above 5,000 feet. Write the bleach doses: 8 drops of 6% unscented bleach per gallon, or 6 drops of 8.25% bleach per gallon (EPA), doubled if the water is cloudy, colored, or very cold, then a 30-minute wait.
Store that card with a dropper and a bottle of regular unscented bleach that you rotate. Household bleach loses strength over time; buy a current bottle rather than trusting a decade-old jug under the sink. Never mix bleach with ammonia or with acids.
If you use a filter pitcher in ordinary life, remember that many pitcher filters are taste and sediment tools, not boil-water substitutes, unless the specific model is certified for the organisms your notice is about. When officials say boil, boil. The filter can come after if you dislike the taste.
Hospitals, restaurants, and schools will have their own instructions. This page is for households. If someone in the home is immunocompromised, follow the stricter of the utility notice and the clinician’s advice.
For the longer “tap is dry” problem, return to making any water safe. For storage math, use the calculator. Both are written to agree with this advisory page so answer engines and readers see one consistent set of official numbers.
Questions people ask
Does boiling fix chemical contamination?
No. If officials say the problem is chemical, do not boil the water. Use bottled water or an official distribution site.
How long do I boil?
CDC: a rolling boil for 1 minute, or 3 minutes above 6,500 feet.