How to Boil or Disinfect Water

After a natural disaster, water may not be safe to drink. Listen to local officials to find out if your water is safe.

**Warning: water contaminated with fuel or other toxic chemicals cannot be made safe by boiling or disinfecting with bleach.

How to disinfect water by boiling

  • Bring tap water to a solid boil. Once the water is steadily boiling, continue to boil for one full minute. Allow to cool. Store water in a clean container (not washed in contaminated water), cover with a tight lid.

  • If the water is cloudy, filter it through clean cloths or allow it to settle, and draw off the clear water for boiling.

  • This includes water used for brushing teeth, making ice, washing raw foods, preparation of drinks, and water for pets. You should throw away ice made during the time the advisory or notice was issued, as freezing does not kill bacteria.

How to disinfect water with bleach

  • If you are unable to boil your water, you can disinfect it with unscented household chlorine bleach using the following instructions. (Warning: do not use bleach that contains any additives, such as scents, as the additives are not safe to use in drinking water).

  • If boiling is not possible, chemical disinfection of filtered and settled water collected from a well, spring, river, or other surface water body will still provide some health benefits and is better than no treatment at all."

  • If the water is cloudy, filter it through clean cloths or allow it to settle, and draw off the clear water for disinfection.

-or-

If the water is cloudy, add ¼ teaspoon of unscented bleach to one gallon of water, stir well, and allow the water to stand for 30 minutes before using.

  • If the water is clear, add 1/8 teaspoon of unscented bleach to one gallon of water, stir well, and allow the water to stand for 30 minutes before using.

If the strength of the bleach is unknown, add ten drops per quart or liter of filtered and settled water. Double the amount of chlorine for cloudy, murky or colored water or water that is extremely cold.

Chlorine Disinfection
Available Chlorine

Drops per Quart/Gallon of Clear Water

Drops per Liter of Clear Water

1%

10 drops per Quart - 40 per Gallon

10 per Liter

4-6%

2 drops per Quart - 8 per Gallon (1⁄8 teaspoon)

2 per Liter

7-10%

1 drop per Quart - 4 per Gallon

1 per Liter

Mix the treated water thoroughly and allow it to stand, preferably covered, for 30 minutes. The water should have a slight chlorine odor. If not, repeat the dosage and allow the water to stand for an additional 15 minutes. If the treated water has too strong a chlorine taste, allow the water to stand exposed to the air for a few hours or pour it from one clean container to another several times.

*Note: If your local health department has issued a Boil Water advisory, follow their instructions on how to make your drinking water safe. At times, local health departments may give instructions on how to boil/disinfect water that are different from those listed here, or different from those given by a health department in another jurisdiction. This is due to the specific contamination situation in your area and you should follow your local health department's instructions.

After a Water Advisory or Notice

After an advisory or notice has been lifted (if contamination of the water system did occur), you should flush household pipes, ice makers, water fountains, etc. prior to using for drinking or cooking. Flushing simply means letting the water run to ensure that no contaminated water remains in your pipes. Follow the these guidelines for flushing:

  • Run all cold water faucets in your home for one minute

  • To flush automatic ice makers, make three batches of ice and discard

  • Run water softeners through a regeneration cycle

  • Run drinking water fountains for one minute

  • Run water coolers with direct water connections for five minutes.

Additional Information