Many travellers, climbers and hikers favour chemical treatment because of lightweight and ease of use.
A bottle of iodine crystals, weighing less than a bottle of painkillers, can be tucked into any pocket and yet has the ability to treat hundreds or thousands of litres of water.
Currently, American-based manufacturers of chemical treatments are required to register them with the Environmental Protection Agency (EPA) Pesticide Branch. This guarantees product ingredients, proper labelling and that the product will perform its function without undue negative affects to the environment.
The EPA does not require manufacturers to substantiate claims about the effectiveness of their products with lab results and Health Canada currently has no guidelines applicable to chemical treatment products.
Generally, iodine and chlorine (referred to as ‘halogens’) are quite effective against all pathogenic microorganisms except Cryptosporidium and helminth eggs and larvae. Halogens have the advantage of low cost, lightweight, ease of use and passive disinfection. This means that you can add the halogen to water and go to sleep or hike a few kilometres while it does the job with no more effort on your part.
Halogens are also useful for keeping disinfected water pathogen-free while it is being stored in jugs or tanks on a sea kayaking trip or at a climbing base camp. Particularly when used with dehalogens, high concentrations of halogens are very effective for disinfecting water and keeping it disinfected until it is needed.
In the future, if portable chlorine dioxide products become cheaper and are shown by independent lab tests to be as effective in the variable conditions faced by travellers and trekkers as in municipal water treatment plants, and without health risks, they could quickly become the chemical treatment of choice.