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   Tip #115 – Emergency Water Disinfection

In the event of a natural disaster, which may compromise your access to water from your tap or bottle source, follow these techniques to purify water for drinking: 

  • Boiling -– vigorously, for 10 minutes
  • Bleaching -– add 10-20 drops of household bleach per gallon of water, mix well, and let stand for 30 minutes.  A slight smell or taste of chlorine indicates water is good to drink. (Note: do not use scented bleaches, colorsafe bleaches, or bleaches with added cleaners.)
  • Tablets -– commercially available purification tablets
  • Solar disinfection, known as SODIS -- a new technique developed by researchers at the Swiss Federal Institute for Environmental Science and Technology.  Clear plastic bottles are filled with water and left in the sun.  The heat warms the water and the combination of warm water and ultraviolet radiation kills most microorganisms.  The Institute’s tests showed that 99.9% of the E. coli in a sample of contaminated water were killed when the sun heated the water beyond 122F (50C).  At that temperature, disinfection takes about an hour, but placing a corrugated metal sheet under the bottle can shorten the time.  Additional tests demonstrate SODIS as an effective approach for killing the cholera bacteria, Vibrio cholerae, and that it could inactivate parasites including the diarrhea-causing Cryptosporidium.


"One of the tests of leadership is the ability to recognize a problem before it becomes an emergency." ~ Arnold Glasgow

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