What to Do When the Water Is Unsafe: Boil Water Advisories Explained

Quick answer: during a boil water advisory, use bottled water or tap water brought to a rolling boil for one minute (three minutes above 6,500 feet) for drinking, cooking, brushing teeth, making ice, washing produce and mixing baby formula. A “do not drink” or “do not use” notice is different, because boiling will not fix chemical contamination. Follow your water utility’s instructions until officials say the water is safe again.

Most people never think about their tap water until a notice taped to the lobby door or a text alert tells them not to trust it. Boil water advisories are common. Water mains break, pressure drops after a storm, a treatment plant has a problem, or a flood pushes contaminated water into places it should not be. None of those situations is rare, and in a large city at least one neighborhood is usually under some kind of water notice at any given time.

The good news is that the steps are simple and well established. The Centers for Disease Control and Prevention publishes clear guidance on boiling and disinfecting water, and the Environmental Protection Agency sets the rules utilities follow when they warn the public. This guide puts that guidance in one place, along with the everyday questions people actually ask: Can I shower? Is the dishwasher safe? What about the coffee maker?

Why Utilities Issue Boil Water Notices

Water systems are pressurized for a reason. Steady pressure keeps outside water and soil from seeping into pipes through cracks or loose joints. A main break, a power failure at a pumping station, or a major firefighting effort can drop pressure low enough that contamination becomes possible. Utilities often issue a precautionary advisory in that situation even before any test comes back positive.

Other notices follow a confirmed problem, such as a test showing E. coli or a breakdown in disinfection. Under the EPA’s Public Notification Rule, water systems must alert customers to the most serious situations, called Tier 1 violations, within 24 hours. Notification can come by television, radio, text alerts, door hangers, social media or posted notices, depending on the system.

There are three common types of notice, and the difference matters:

• Boil water advisory or notice: germs may be present. Boiling makes the water safe for drinking and cooking.
• Do not drink notice: a contaminant is present that boiling may not remove. Use bottled water for drinking and cooking, though the water may still be fine for some other uses as instructed.
• Do not use notice: the water should not be used for any purpose, including bathing, often because of chemical contamination.

Boiling kills germs, but it does not remove chemicals, metals or fuel. The CDC notes that boiling water contaminated with chemicals can actually concentrate them as water evaporates. Read the exact wording of your notice before deciding what to do.

How to Boil Water Correctly

The CDC method is short. Bring clear water to a full rolling boil, the kind with big bubbles that keep breaking even when you stir, and hold it there for one minute. Above 6,500 feet, boil for three minutes, because water boils at a lower temperature at high altitude.

1. Fill a clean pot with tap water. Cloudy water should settle first, then be filtered through a clean cloth, paper towel or coffee filter.
2. Bring it to a rolling boil and keep it boiling for one minute, or three minutes at high elevation.
3. Let it cool naturally. Avoid adding ice made from the unsafe water.
4. Pour the water into clean, sanitized containers with tight lids.
5. Label the containers and keep them in the refrigerator or a cool place.

Boiled water can taste flat. The CDC suggests improving the taste by pouring it back and forth between two clean containers, or by adding a pinch of salt to each quart. For people without power, our guide to boiling water without electricity covers camp stoves and other options, along with the ventilation rules that keep them safe.

Disinfecting Water When You Cannot Boil It

A power outage combined with a water advisory is a common pairing after storms. When boiling is impossible, the CDC says plain, unscented household liquid bleach can disinfect water against most germs. Check the label for the sodium hypochlorite percentage, and skip any bleach with scents, color-safe formulas or added cleaners.

• For bleach that is 6 percent sodium hypochlorite: add 8 drops per gallon of water.
• For bleach that is 8.25 percent sodium hypochlorite: add 6 drops per gallon of water.
• Stir well and let the water stand for at least 30 minutes before using it.
• Water should have a slight chlorine smell afterward. No smell at all calls for another dose and another 15-minute wait.

Bleach is less effective against some parasites, such as Cryptosporidium, than boiling is. Water treatment tablets and some filters are other options, though each product has its own instructions and limits. The CDC points out that many portable filters remove parasites and some bacteria but not viruses, so read the packaging closely. Our article on ways to purify water compares methods side by side, and why filtering matters in an emergency explains where filters fit.

Everyday Tasks: What Needs Safe Water and What Does Not

Here is where most of the confusion sits. CDC guidance for boil water advisories breaks it down task by task.

Drinking, cooking and brushing teeth

Use bottled or boiled water for all of these. That includes rinsing your toothbrush, mixing juice or drink powders, and preparing any food that will not be cooked further. Washing fruits and vegetables also calls for safe water.

Baby formula

Infants are especially vulnerable. Prepare formula with bottled water or water that has been boiled and cooled. Ready-to-feed formula, which needs no added water, is another choice during an advisory. Ask a pediatrician about anything specific to your baby.

Ice, coffee makers and refrigerator dispensers

Throw away ice made during the advisory and turn off automatic ice makers. Refrigerator water dispensers and coffee makers that pull from the water line should not be used until the notice ends. A coffee maker that does not hold water at a boil does not make water safe.

Showering and bathing

The CDC says showering or bathing is generally fine, but be careful not to swallow any water. Supervise young children in the bath, and consider giving babies and toddlers a sponge bath instead so they do not drink the bathwater.

Handwashing

In most cases, the CDC says washing hands with soap and tap water is safe during a boil water advisory. Follow any different instructions from your health department, and use hand sanitizer as a backup when soap and water are not available.

Dishes

A household dishwasher is generally safe to use, according to the CDC, if the water reaches a final rinse temperature of at least 150 degrees Fahrenheit or the machine has a sanitizing cycle. Hand-washing dishes calls for an extra step: wash and rinse as usual, then soak the dishes for about a minute in a sanitizing solution of one teaspoon of unscented bleach per gallon of warm water and let them air dry.

Pets

Pets can get sick from some of the same germs people do. Give them bottled or boiled water that has cooled.

How to Hear About an Advisory, and Who Should Take Extra Care

A notice does little good if it reaches you two days late. Most water utilities post advisories on their websites and social media, and many cities route them through the same text and email alert systems used for storms. Sign up with your water provider directly, since the company name on your water bill may differ from your city government. Renters should ask the building manager how notices reach tenants, because the water account is often in the landlord’s name and the utility may contact the owner rather than the people living in each unit.

Local television and radio stations usually carry larger advisories, and the boundaries are often published as a map or a list of streets. Advisories can cover a few blocks around a main break or an entire service area. Check the map carefully. Neighbors across the street may be on a different side of a pressure zone and get different instructions.

Some people should be especially careful about following the notice to the letter. The CDC identifies infants, older adults, pregnant people and anyone with a weakened immune system, such as people receiving chemotherapy, transplant recipients and people living with HIV, as more likely to get seriously ill from waterborne germs. Anyone in those groups who develops diarrhea, vomiting, stomach cramps or fever during or after an advisory should contact a health care provider. Mention the water notice, since that detail can help a clinician decide on testing.

Households with someone in a high-risk group should keep a larger store of bottled water than the minimum, so nobody has to make a tired late-night decision about whether the tap is good enough. A few extra gallons on a closet shelf costs little and removes the guesswork.

Keep a Water Reserve So an Advisory Is an Inconvenience

The calmest households during a water notice are the ones that already had water on a shelf. Ready.gov recommends storing at least one gallon of water per person per day for several days, for drinking and sanitation. Pets, hot weather, pregnancy and illness all raise that amount.

Store-bought bottled water is the simplest option and should be kept sealed until you need it. Water you store yourself belongs in food-grade containers that have been cleaned and sanitized, and it should be replaced every six months, per Ready.gov. Our guide to storing water for emergencies walks through containers, rotation and where to put them in a small apartment.

A few small items make an advisory easier to manage: a large stockpot with a lid, a funnel, a few clean pitchers with lids, a bottle of plain unscented bleach checked for its expiration date, a medicine dropper, and masking tape and a marker for labels.

After the Advisory Is Lifted

Utilities announce when water is safe again, usually after lab tests come back clean. Do not assume it is over just because the tap water looks fine. Once the all-clear is official, the CDC and most utilities recommend a short reset routine:

1. Run all cold water taps for several minutes to flush the plumbing, following any time your utility gives.
2. Empty and clean the ice maker, throwing out the first few batches of ice.
3. Run water coolers, refrigerator water lines and dispensers to flush them, and replace filters as the manufacturer directs.
4. Flush and clean any home water treatment devices, such as softeners, according to their instructions.
5. Run an empty cycle on the dishwasher and the coffee maker.

Well owners face a different process. Private wells are not covered by utility advisories, and after flooding the CDC recommends that well water be tested and disinfected before drinking. Your local health department can explain testing options. For flooded areas, our flood safety guide explains why floodwater itself is a contamination hazard.

Frequently Asked Questions

How long should I boil water during a boil water advisory?

Bring it to a full rolling boil and keep it boiling for one minute. Above 6,500 feet, boil it for three minutes, as the CDC recommends.

Can I shower during a boil water notice?

Generally yes, according to the CDC, as long as you avoid swallowing water. Supervise children closely and consider sponge baths for babies.

Is it safe to brush my teeth with tap water during an advisory?

No. Use bottled or boiled water to brush teeth and rinse your toothbrush until the advisory ends.

Does a water filter pitcher make water safe during a boil advisory?

Not reliably. Most pitcher filters are designed to improve taste and reduce certain contaminants, not to remove all bacteria and viruses. Boil the water or use bottled water unless the filter is certified for the germs involved and your health department says it is acceptable.

What is the difference between a boil water notice and a do not drink notice?

A boil water notice means germs may be present and boiling makes the water safe. A do not drink notice means there is a contaminant boiling may not remove, and boiling can even concentrate some chemicals. Use bottled water when told not to drink.