Contaminated Water

• Water that is contaminated following a natural disaster or that is unsafe because of viruses or bacteria can be purified by adding bleach. Washington State Department of Health outlines the following instructions for the proper amount of bleach to add to contaminated water. For water that is clear to cloudy, add 3 drops to every qt., 5 drops to every 1/2 gallon; 1/8 tsp. to every gallon; 1/2 tsp. to every 5 gallons and 1 tsp. to every 10 gallons. For water that is cloudy, very cold or surface water, add 5 drops to every qt., 10 drops to every 1/2 gallon; 1/4 tsp. to every 1 gallon; 1 tsp. to every 5 gallons and 2 tsp. to every 10 gallons. Close the container; swish around and let stand for 30 minutes before use.
  
  

Emergency Household Water

• To prepare water in the event of an emergency, use a 10-gallon container, and fill it with water from a source that has not been treated with chlorine. Add 2 tsp. of bleach, close the container and swish around. Label the top with the date, and store in a dark, cool place for up to 6 months. If storing water that has been commercially treated, omit the 2 tsp. of bleach.
  
  

Type of Bleach

• Liquid household bleach is the best type of bleach to use when treating contaminated water or when preparing water for emergency storage. Household bleach contains between 5 and 6 percent chlorine. Bleaches that have fragrance or other additives should not be used.
  
  

Containers

• Always use clean containers to store water. Do not reuse containers that previously contained toxic materials like antifreeze, solvents or pesticides. If reusing plastic soda bottles to prepare water for emergency storage, first thoroughly clean with soap and water, and carefully rinse to remove any residual soap. Add 1 tsp. of bleach to 1 qt. of water, close the bottle and swish around to sanitize the container. Empty the bleach water solution, and rinse the sanitizing solution with clean water.