Emergency Disinfection of Drinking Water

If a community or well water system with clean water is not available, it is important to find safe water or disinfect water for drinking, cooking, and brushing teeth.

U.S. federal agencies and the Red Cross recommend these same four steps to disinfect drinking water in an emergency.

1. Use bottled water that has not been exposed to flood waters if it is available.
2. If you don’t have bottled water, you should boil water to make it safe. Boiling water will kill most types of disease-causing organisms that may be present. If the water is cloudy, filter it through clean cloths or allow it to settle, and draw off the clear water for boiling. Boil the water for one minute, let it cool, and store it in clean containers with covers.
3. If you can’t boil water, you can disinfect it using household bleach. Bleach will kill some, but not all, types of disease-causing organisms that may be in the water (Chlorine and iodine may not be effective in controlling more resistant organisms like Cryptosporidium). If the water is cloudy, filter it through clean cloths or allow it to settle, and draw off the clear water for disinfection. Add 1/8 teaspoon (or 8 drops) of regular, unscented, liquid household bleach for each gallon of water, stir it well, and let it stand for 30 minutes before you use it. Store disinfected water in clean containers with covers.
4. If you have a well that has been flooded, the water should be tested and disinfected after flood waters recede. If you suspect that your well may be contaminated, contact your local or state health department for specific advice.

Information on Emergency Disinfection of Drinking Water:

Emergency Disinfection of Drinking Water (EPA)

Information on Well Remediation and Disinfection after Flooding:

Disinfecting Wells Following an Emergency (CDC)

What to Do After the Flood (EPA)

Information on Water Treatment:

Water Treatment Methods (CDC)

A Guide to Drinking Water Treatment and Sanitation for Backcountry and Travel Use (CDC)

A Guide to Drinking Water Treatment for Household Use (CDC)

Information on Bottled Water:

Bottled Water (CDC)

Bottled Water Regulation and the FDA (FDA)