Finding a Water Filter
A drinking water system is basic safety equipment for any traveler or hiker. Untreated water can contain protozoa, giardia or cryptosporidium, bacterium like E. coli and other parasites. The ability to screen out viruses, size and other features will help determine the filter system thats right for you.
Potable water describes the drinkable quality of water that has been treated to remove any harmful microorganisms. For safetys sake, virtually any water taken from streams or lakes should be treated, or made potable, before its consumed. This is true whether youre camping in a national park or canoeing in a tropical rainforest.
Protozoa are the single-cell parasitic microorganisms causing the most water-related illnesses in the United States.
Giardia, the most common protozoa, attaches to the wall of the
intestine and wreaks havoc in the digestive system. Protozoa are resistant
to iodine and must be removed
Bacteria are smaller than protozoan cysts, but no less unpleasant.
Cholera, Salmonella and E. Coli. Some bacteria are small enough to pass through a filter and must be eliminated with chemical disinfection. Virulent strains of E. coli, such as Escherichia coli, can multiply quickly in the intestinal tract. First symptoms usually begin within twelve hours of ingestion. As the infection runs its course, it may cause cramping, water loss, diarrhea and other various discomforts.
Viruses are the smallest and most dangerous water contaminants, causing life-threatening diseases such as polio and hepatitis. They are particularly a concern for water outside North America; however, they most often occur in areas with significant human contact. Small enough to fit through a filter, they must be removed by chemical disinfection.
Boiling your drinking water, while less convenient, is still an
Chemical Disinfection is generally lightweight, inexpensive, effective
and easy to use. However, without a neutralizer, the taste is strong and
unpleasant. Adding a little lemonade or other powdered drink mix can help
mask the taste.
Filtration is the most foolproof way to create potable water.
A water filter blocks the passage of objects through a porous filter.
Filters are ranked on a pore-efficiency rating, which roughly corresponds
to the smallest object that can pass through it. A filter with a one-micron
rating will eliminate most protozoa. It takes a filter with a rating of
0.2 microns to get bacteriumas well as parasites.
Filter Usage Tips
Page Last Updated 4/14/02
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