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Emergency Preparedness

How to Disinfect Your Water

During a disaster or an emergency such as fire, earthquake, flood, contaminous event or hazardous chemical spill, please follow these EPA-recommended tips on how to disinfect your water:

USE ONLY WATER THAT HAS BEEN PROPERLY DISINFECTED WHEN DRINKING, COOKING, MAKING ANY PREPARED DRINK, OR FOR BRUSHING TEETH.

1. BOTTLED WATER: Use bottled water that has not been exposed to flood water if it is available.

2. BOILING: If you do not have bottled water, you can 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. Then, draw off the clear water for boiling. Boil the water for one minute, let it cool, and store it in clean containers with covers.

  • Filter murky or colored water through clean clothes or allow it to settle. It is better to do both: filter and then let the water settle.
  • Boiling is the best method to make water safe because it kills many disease-causing microorganisms like Giardia lamblia and Cryptosporidium, which are frequently found in rivers and lakes.
  • To improve the flat taste of boiled water, aerate it by pouring it back and forth from one container to another. Allow it to stand for a few hours or add a pinch of salt for each quart or liter of water boiled.

3. DISINFECTING: If you cannot boil water, you can disinfect it by using household bleach. Bleach will kill some, but not all, types of disease-causing organisms that may be in the water. If the water is cloudy, filter it through clean cloths or allow it to settle. Then, 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.

  • When boiling is not practical, certain chemicals will kill most harmful or disease-causing organisms. Chlorine (in the form of unscented bleach) and iodine are the two chemicals commonly used to treat water.
  • You can use non-scented, household chlorine bleach that contains a chlorine compound to disinfect water. Note:1/8 teaspoon and 8 drops are about the same quantity.
  • You can use a small amount of iodine to disinfect filtered and settled water. Common household iodine from the medicine chest or first aid kit may be used to disinfect water. For cloudy water add ten drops and let the solution stand for at least 30 minutes.

4. WATER WELLS: If you have a water well that has been flooded, the water from it should be tested and disinfected after floodwater recedes. If you suspect that your well may be contaminated, contact your local or State Health Department or Agriculture Extension Agent for specific advice.

If you would like to learn more about disinfecting your contaminated water after a disaster or emergency, please visit the US EPA online at www.epa.gov