A friend once hypothesized that by drinking untreated water from scuzzy sources—ponds, puddles and swamps—he would develop a tolerance to water-borne pathogens.
After seven years of intolerant bowels, he finally got around to visiting a doctor and learned that his intestines were home to countless varieties of pathogenic cling-ons. Ridding his body of these parasites, he said, was even worse than hosting them.
While drinking from a puddle is—for most—an obvious no-no, the threat of contamination exists in virtually all bodies of water. In canoe country, waterborne nasties fall into the ranks of protozoa, bacteria and viruses. Protozoa cause unpleasantries such as giardiasis. These are the largest pathogenic micro-organisms, measuring in at one micron (one-thousandth of a millimetre) or more. Bacteria are ubiquitous in most bodies of water and can generally be consumed without harm. The odd few, however, trigger diarrhea and dysentery.
Most measure about one micron in size, though some particularly dangerous ones, such as e. coli, are smaller. Viruses are less common in North America but can be smaller than 0.1 microns and cause diseases like polio. They are more of a concern for those in developing countries.
The simplest means of ensuring your water is clean is to boil it. While most cooties are eradicated once water hits 100 degrees Celsius, you’re best to boil for three to five minutes to be safe. This means boiled water used for cooking need not be treated by other means.
But scalding water tends not to be too thirst-quenching. Canoe trippers have long treated suspect water with a few drops of bleach or iodine. These old-school chemicals require proper incubation times of up to an hour depending on water temperature and murkiness. What’s more, both have associated health risks: bleach destroys intestinal micro-organisms known to aid in digestion, and pregnant women should not drink iodine-treated water.
A better chemical treatment employs a solution of chlorine dioxide—the same chemical used in municipal water treatment plants. Treatment involves mixing liquid chemical components (like the Pristine drops at right) or by using a battery powered device (such as the MSR Miox) that produces a briny mixture of water-purifying oxidants. Wait times are generally less than 10 minutes.
Battery-generated short-wavelength UV-C units employ light to attack the DNA of microbes, meaning the microbes can’t reproduce and wreak havoc inside you. As is the way with lightbulbs, the units are fragile while not in their case but work in less than two minutes for amounts up to one litre.
Water filters force water (by way of pumping or gravity) through microscopic pores. Filters remove all protozoa and, depending on pore size, bacteria also. A typical 0.5 micron filter will remove all but a select few (and less common) bacteria; some manufacturers add a thinner-gauge pre-filter to screen out all bacteria.
Water purifiers are essentially filters as described above with a layer of iodine resin to inactivate viruses and over the highest level of protection. Many filters and purifiers feature a carbon core to remove tastes and residual iodine.
Whether you’re using chemicals, UV light, filters or purifiers, it makes sense to start with the cleanest water possible. Collect away from shore or filter over the gunwale. Allow silty water to settle in a pot before pumping. Over time, filter and purifier cartridges will become clogged with particulates and need to be cleaned by scrubbing, and eventually replaced.
This photo is courtesy of Flickr user nucce.