UMEM Educational Pearls

Title: When Water is Undrinkable

Category: International EM

Keywords: water, international, cryptopsporidium, chlorine, iodine, boiling (PubMed Search)

Posted: 11/28/2012 by Andrea Tenner, MD
Click here to contact Andrea Tenner, MD

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.