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General Information:
• Millions of people around the world (including our patients who travel and victims of disasters like Hurricane Sandy) are exposed to non-potable water.
• How to treat contaminated water:
♦ Filter cloudy water through a clean cloth or allow to settle prior to treatment
♦ The safest method is boiling water vigorously for 1 minute (or, at least 3 minutes at altitudes >6,000ft)
♦ Chemical disinfection is not as effective but, if boiling is not possible, use either:
• 2 drops of unscented bleach (5.52% Cl) per quart/liter of water. (Unknown strength? Add 10 drops per quart/liter.)
-Or-
• 5 drops of tincture of 2% iodine per quart/liter.
- If the water is cloudy or cold, double the chlorine or iodine.
- Notes: Pregnant women or people with thyroid conditions should not use iodine
♦ UV decontamination can be accomplished by leaving clear bottles of water in direct sun for >6 hours or special equipment, but requires clear water
• Boiling, Chlorine/Iodine, and UV will kill viruses, bacteria, and Giardia
• Only Boiling kills Cryptosporidium
Bottom Line:
• If bottled water is available, use it.
• If not, boil your water.
• In order to treat for a wide variety of pathogens, it is best to combine available methods.
University of Maryland Section for Global Emergency Health
Author: Andi Tenner
References
United States Environmental Protection Agency. Water Health Series: Filtration Facts. 2005. http://water.epa.gov/drink/info/upload/2005_11_17_faq_fs_healthseries_filtration.pdf
United States Environmental Protection Agenecy. Emergency Disinfection of Drinking Water. 2006. http://water.epa.gov/drink/emerprep/emergencydisinfection.cfm .
United States Center for Disease Control. Water Treatment Methods. 2011. http://wwwnc.cdc.gov/travel/page/water-treatment.htm.