Emergency Information
If you are uncertain how pure your water source is, you should purify the water before consuming or storing it.
The treatments described below work only in situations where the water is unsafe because of the presence of bacteria or viruses. If you suspect the water is unsafe because of chemicals, oils, poisonous substances, sewage or other contaminants, do not use the water for drinking.
To purify your water, follow these steps.
Boiling
Boiling is the safest way to purify water. Bring the water to a rolling boil for 3-5 minutes and let it cool before drinking.
Purifying With Bleach
If boiling is not possible, treat water by adding liquid household bleach, such as Clorox or Purex. Household bleach is typically between 5 percent and 6 percent chlorine. Avoid using bleaches that contain perfumes, dyes, or other additives. Be sure to read the label.
Place the water (filtered, if necessary) in a clean container. Add the amount of bleach listed in the table below. Mix thoroughly and allow to stand for at least 30 minutes before using (60 minutes if the water is cloudy or very cold).
| Volume of Water to be Treated |
Treating Clear/ Cloudy Water Bleach Solution to Add |
Treating Very Cold or Surface Water Bleach Solution to Add |
|---|---|---|
| 1 quart/1 liter | 3 drops | 5 drops |
| 1/2 gallon/2 quarts/2 liters | 5 drops | 10 drops |
| 1 gallon | 1/8 teaspoon | 1/4 teaspoon |
| 5 gallons | 1/2 teaspoon | 1 teaspoon |
| 10 gallons | 1 teaspoon | 2 teaspoon |
For more information, see Purifying Water During an Emergency from the Washington State Department of Health.