How long do I need to boil water to make it safe?

Bring clear water to a rolling boil for 1 minute. At elevations above 6,500 feet, boil for 3 minutes. If the water is cloudy, filter it through a clean cloth or coffee filter first, or let it settle and draw off the clear water.

How much bleach do I add to disinfect water?

Add 8 drops, about 1/8 teaspoon, of unscented household bleach (5 to 9% sodium hypochlorite) per gallon of clear water. Double the amount for cloudy water. Stir and let stand for 30 minutes before use; the water should have a slight chlorine smell.

Does boiling water remove chemical contamination?

No. According to the CDC, water contaminated with fuel or toxic chemicals is not made safe by boiling or disinfection. If you know or suspect chemical contamination, switch to stored or bottled water and follow guidance from your local health department instead.

What should I do if my private well was flooded?

Have the well tested before drinking from it again, and disinfect it following guidance from your local health department or state extension office. Flooded wells can carry contamination even after the water looks clear.

Can I use bleach-treated water for baby formula?

Bottled water or water you have properly boiled is generally preferred for mixing infant formula during a contamination event. If you are breastfeeding, continue breastfeeding, since it does not carry the same water-safety concerns as formula preparation.

Hazard Checklist

Water Contamination Checklist. Before, during, and after.

A step-by-step checklist for a boil-water notice or a suspected contamination event. Print it for your refrigerator or save it to your My Readiness dashboard.

1 min

rolling boil to kill germs (3 min above 6,500 ft)

8 drops

unscented bleach per gallon of clear water

30 min

wait time before drinking bleach-treated water

Never

boiling or bleach removes chemical contamination

Phase 1

Before contamination. Know the two different problems.

Germs and chemicals both make water unsafe, but they call for different responses. Knowing which one you are dealing with, and having a treatment method ready either way, matters more than any single supply.

Water

Store 1 gallon per person per day for at least 3 days, including pets
Work toward extending storage to the same rate for 14 days in sealed, dated containers
Get a way to treat additional water: a gravity filter or water treatment tablets, either under $30 and good for years
Have a second treatment method in case your primary fails. Boiling, chemical treatment, or a second filter gives you redundancy
Add a chemical contamination note to your water plan: boiling addresses germs but not fuel, chemicals, or flood contamination
Learn the boil-water and bleach-disinfection steps before you need them under pressure

Sanitation

Stock basic hygiene supplies for 14 days: soap, hand sanitizer, toilet paper, and personal care items

Communications

Turn on Wireless Emergency Alerts to receive boil-water notices as soon as they are issued

Phase 2

During contamination. Match the treatment to the threat.

A boil-water notice and a chemical contamination warning call for different responses. Getting this distinction right matters more than acting fast on the wrong method.

Following a Boil-Water Notice

Stop using tap water for drinking, cooking, and brushing teeth until you know it is safe
Boil clear water at a rolling boil for 1 minute (3 minutes above 6,500 feet), or use 8 drops of unscented bleach per gallon and wait 30 minutes
Use bottled or already-treated water for infant formula. Continue breastfeeding if you are nursing
Keep pets away from untreated tap water too

If Chemical Contamination Is Suspected

Do not boil or chemically treat water that may contain fuel, industrial chemicals, or pesticide runoff. Neither method removes these contaminants
Switch immediately to stored or bottled water and follow guidance from your local health department
Note any unusual odor, color, or oily sheen and report it to your water utility
Avoid showering or bathing in water you suspect contains chemical contamination until officials confirm it is safe

Phase 3

After contamination. Clear does not always mean safe.

Water that looks fine again is not always safe again. Waiting for the official confirmation, and testing a well if you have one, closes out the event properly.

Returning to Normal Use

Wait for your water utility or health department to issue an official all-clear before resuming normal tap water use
Flush your home's plumbing as directed. Utilities often recommend running cold taps for several minutes after an advisory lifts
Clean and sanitize any container that held contaminated water before reusing it
Replace water filter cartridges that were in use during the contamination event

If You Have a Private Well

Have your well tested after flooding or any suspected contamination before drinking from it again
Disinfect a flooded well following guidance from your local health department or state extension office
Watch for signs of continued contamination: unusual taste, odor, or color after treatment
Keep a stored backup supply on hand. Wells can take time to test and clear

Gear

Still need to get equipped? Start here.

A few items do most of the work when the tap water isn't safe. These are the ones worth having ready.

Browse all gear reviews →

My Readiness

Save this checklist to your dashboard

Free account. Access your saved checklists from any device. No spam.

Personalize

Get a checklist built for your household

Answer 21 questions about your home, location, and situation. We'll tailor this checklist and every other one to match.

Take the Assessment

Keep Going

Browse all checklists