Travel Reference
In-Depth Information
but four hours is a long time to wait for disinfection to take place. Water disinfection sys-
tems must be fast, or they will not be used.
The unit is approximately the size ofasmall Maglite® andweighs 3.5ounces, although
the entire kit, which includes test strips, an instruction booklet, a reference card, and a car-
rying sack, weighs 8 ounces. It is available online from a number of companies but is rel-
atively expensive.
Thissystemappearstobeparticularlyvaluableforindividualswhohaveiodineallergies
andhyperthyroidismandmustusesomedisinfectantotherthaniodine.Usuallywaterneeds
to be filtered—four hours is a long wait. A bottle of tetraglycine hydroperiodide tablets or
saturated aqueous iodine is smaller than this device and far cheaper.
Chlorine Dioxide
Chlorine dioxide (ClO
2
) has been used for many years as a disinfectant in a number of
applications. It is rapidly effective against a wide variety of organisms including bacter-
ia, protozoa, viruses, molds, spores, and mildew. It has 2.6 times the oxidizing capacity of
chlorine and is four to seven times as biocidal as sodium hypochlorite at equivalent con-
centrations. However, for most applications chlorine dioxide has to be generated at the site
whereitisusedbecauseitisunstable(explosive)andlargequantitiescannotbetransported
or stored.
Only in recent years has a technique for producing tablets that release chlorine dioxide
been developed. The tablets have a highly engineered surface that features sites at which
the activator is located and numerous pores. When the tablet is immersed in water, the ac-
tivator reacts with chlorite contained in the rest of the tablet to generate chlorine dioxide.
The reaction takes place in the pores because only in that location is the concentration of
chlorite high enough to produce chlorine dioxide at a sufficiently rapid rate to make the
system practical. The pH of the water is not changed as it is in most commercial chlorine
dioxide generating processes because the reaction is largely limited to the pores.
Chlorine dioxide was first used for water disinfection in 1944. It is effective at low con-
centrations and over a wide pH range. It biodegrades in the environment and does not gen-
erate harmful byproducts. It does not leave a residual chlorine taste or smell. Distributors
claim it actually improves the taste and smell of water.
The tablets are distributed in foil strips that donot allow contact with water orthe mois-
ture in air. To use, the foil packet should be cut open and the tablet quickly dropped into a
literofwater,whichshouldbeplacedoutofdirectsunlightduringdisinfection.Destruction
ofbacteria andvirusesrequiresfifteenminutes;elimination of
Cryptosporidia
and
Giardia
requires up to four hours.
Chlorine dioxide tablets are being produced by at least three manufacturers: Potable
Aqua® (Chlorine Dioxide Tablets), Katadyne® (Micropur®), andAquamira® (Water Pur-
ifier Tablets).
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