Despite the recent reports, stream water still poses a risk
TO filter or not to filter? The result of a recent study has some wilderness experts questioning whether water purification practices are always necessary in the backcountry.
It depends partly on who or what is up there with you, says Dr. Robert Derlet, a professor of emergency medicine at UC Davis, Sacramento.
Derlet, a backpacker for 50 years, sampled water from the wilderness areas of the Sierra Nevada over several years and reported the results of water analysis from 60 sampling sites in the spring 2006 issue of the journal Wilderness and Environmental Medicine.
He categorized sites by whether they were used most by backpackers or pack animals, cattle and sheep, and whether they were in grazing areas or natural areas that humans and domestic animals don’t often visit.
Only one of 15 backpacker sites yielded coliform bacteria, Derlet says. The bacteria indicate a risk for harboring of microbes capable of causing human disease.
All 15 sites sampled downstream of cattle-grazing areas grew coliform, he found, and 12 of 15 sites with heavy pack-animal traffic did. All coliform bacteria he found were Escherichia coli, which can cause diarrhea.
The study produced important clues about when it’s necessary to treat water in the wilderness, Derlet says, but its other important finding is that backpackers aren’t primarily to blame for water pollution, at least not nearly as much as cattle are.
Backpacker Magazine also conducted a nationwide study of wilderness water several years ago, asking readers and its editors to collect samples all over the country. It published the results in December 2003.
“We were primarily testing for Giardia and Cryptosporidium,” says Jonathan Dorn, the magazine’s editor in chief. The organisms can cause intestinal distress. “The results were actually fairly positive. Only one location that actually flunked the test had enough pathogens to require filtering the drinking water.”
But another expert always filters his water. “I just don’t like to take a chance,” says Dr. Robert Norris, editor in chief of Wilderness and Environmental Medicine and chief of the division of emergency medicine at Stanford University Medical Center in Palo Alto. “You just don’t know what is above you.”
For those following Norris’ advice, the Centers for Disease Control and Prevention recommends three options for purifying your drinking water:
* Boil vigorously for one minute (or for three minutes at altitudes greater than 6,562 feet) and allow to cool to room temperature.
* Use a chemical disinfectant with iodine (such as Coghlan’s, Globaline or Potable-Aqua).
* Use a portable water filter, which can remove some microorganisms. But most portable filters on the market don’t effectively remove viruses, the CDC says, so the agency also recommends chemical disinfection. Filters with a pore size of 0.1 to 1 micrometer are meant to take out parasites as well as most diarrhea-causing bacteria, the CDC says. But viruses are smaller than 0.1 micron in size, according to the CDC.
Water isn’t your only worry if you want to enjoy a backpacking trip. “Backpacking is a remarkably safe sport,” Dorn says, but “there are certain specific health worries.”
Being in good physical condition is important. Norris and Derlet recommend cross-training such as walking or bicycling to get in shape.
Training to handle the amount of gear you expect to carry can also help.
“A lot of people are reluctant to train with the pack on their back,” Dorn says, “because they think they will look geeky walking around the local park or on the treadmill at the gym.” But he often does it before a big trip.
“It develops the lower body power and endurance you need.” It’s not necessary to put in exactly what you’ll take; simply include about the same number of pounds you expect to tote. “I’ll put in big jugs of water,” Dorn says, “or, at the gym, a couple barbell plates.”
Trim down the load, Derlet says, especially if it’s your first trip. “People take too much.” Get back to basics, he advises.
Paying attention to gear helps reduce problems. “Make sure your boots are broken in,” Derlet says. “Hike on trails at least two or three times” with new boots, he tells backpackers.
Derlet and Norris are fans of wool socks because they leave their feet blister-free. Norris adds a liner sock under the wool to wick away moisture.
Consider getting your backpack professionally fitted, Norris says, so it fits you well and will reduce the risk of sores or blisters.
Novices should start with a two-night trip, Derlet advises. Find a reputable organization, such as the Sierra Club, experts advise, or go with recommendations from veteran backpackers.
Protect against sunburn by using a sunscreen with an SPF of at least 15.
Derlet advises insect repellent with 20% DEET (N,N-diethyl-m-toluamide).
And drink plenty of water to avoid dehydration.
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Healthy Traveler appears every other week. Kathleen Doheny can be reached at kathleendoheny@earthlink.net.
