Travel Reference
In-Depth Information
and halogenation with a charcoal matrix. Charcoal filtration should be used after halogen
disinfection because it removes iodine or chlorine from water.
When the charcoal binding sites are full, compounds pass through unadsorbed or dis-
place other chemicals from the charcoal. Color or taste in the water indicates that the car-
bon is exhausted and should be replaced. However, the capacity is large and the filter usu-
ally clogs before the charcoal is exhausted. Charcoal does not adsorb all microorganisms
and does not kill them, so it does not disinfect.
DESIRABLE CHARACTERISTICS OF WATER DISINFECTION SYSTEMS
Awaterdisinfectionsystemforuseinthewildernessordevelopingcountriesmusthaveall
of the following characteristics:
Simple and convenient
Fast
Small and lightweight
Reliable
Wilderness users tend to be young and impatient; many will not use a system that is
not simple and convenient or will not wait for a slow process. They may consume water
without disinfection if it appears clear and uncontaminated. They will not carry a system
that is not small and lightweight. A system that is not reliable should not be used by any-
one.
Disinfection systems suitable for wilderness use are also suitable for urban use in coun-
tries with an unsafe water supply. However, long-term residents usually develop a more
convenient system, optimally one that combines a filter with chemical or ultraviolet treat-
ment.
GOALS OF WATER DISINFECTION
The goal of water disinfection is the elimination of waterborne microorganisms. Unlike
urban systems, the techniques used to disinfect small quantities of water usually kill all or-
ganisms.
Three types of microorganisms must be eliminated: parasites, bacteria, and viruses.
Someparasitesaresingle-cellorganismssuchas Cryptosporidia, Cyclospora, Giardia ,and
amoebae; others are larger, multicellular organisms, such as tapeworms or roundworms.
When eliminated from the body, single-cell parasites often form thick, tough walls
around themselves—cysts—that are much more resistant to chemical agents or heat than
the unprotected organism. More complex parasites lay eggs that are excreted by the host.
Bacteria, which are intermediate in size between parasites and viruses, make up most of
thebulkoffeces.Theyproduceawiderangeofinfections,manyofthempotentiallylethal.
 
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