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How To Disinfect Water by Boiling


Updated January 23, 2014

Giardia lamblia and Cryptosporidium are commonly found in rivers and lakes. Boiling is the best method to remove these types of organisms.

Always choose flowing water sources (rivers and streams) over stagnant water (lakes and ponds) and disinfect before using. Well water is usually safe, but can become contaminated during a flood. Don't consume well water after a natural disaster unless instructed to do so by authorities.

Unless water has been deemed safe by authorities, it must be disinfected before drinking, cooking, making prepared drinks (such as baby formula), or brushing teeth.

Difficulty: Easy

Time Required: 2-3 Hours

Here's How:

  1. Filter cloudy water through clean cloths or coffee filters.
  2. Let water sit for an hour or two after filtering to allow any sediment to settle. Pour the clear water off the top into another container. Be careful not to dump the sediment into the new container.
  3. Boil filtered and settled water vigorously for one minute (at altitudes above a mile, boil for three minutes). Don't start the clock until you have a good rolling boil going.
  4. To improve the taste of boiled water, aerate by pouring it back and forth between containers and let it stand for a few hours. You can also add a pinch of salt for each quart (or liter) of boiled water.
  5. Store boiled water in clean containers with covers.


    "Emergency disinfection of drinking water." 28 Nov 2006. Ground water and drinking water. US EPA. 27 Nov 2007.

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