Purifiers so packable they’ll never get left behind
There’s a chance, just a chance, that you could dip your Sierra cup into a crystalline mountain stream, quaff heartily, and avoid all consequences save slaking your thirst. But the odds are better that you’d pay for your indiscretion a couple of days later. While doubled-over from cramps and other intestinal indignities, you’ll vow never again to shave grams from your pack by jettisoning your handheld water filter.
I speak with the zeal of a repentant filter-jettisoner because I know all too well what can be wreaked by the microvermin that lurk in even the most pristine-seeming water — critters like giardia and cryptosporidium pack a visceral wallop, and you’ll never see ’em coming. These days, there’s really no excuse for going without a filter: The handheld models are getting more compact, lighter, and easier to use. And with prices starting around $30, it should be simple enough to strain the vermin without straining your wallet.
The goal of a filter is to rid your drinking water of microscopic contaminants, rendering water clear and somewhat pure, depending on the size of the filter’s pores — more specifically, what manufacturers call pore-size efficiency. A filter with a rating of one micron or smaller will remove protozoa like giardia and cryptosporidium, as well as parasitic eggs and larva, but it takes a pore-size efficiency of less than 0.4 microns to remove bacteria. All of the filters here take care of bacteria.
If you travel in the Third World, or places where water might be contaminated by sewage, you’ll have to concern yourself with viruses. Until recently, that meant getting a filter that incorporated iodine, or using iodine tablets like Potable Aqua. One filter in this review, though, claims to meet EPA virus-removal standards by filtration alone: Good news, because iodine tastes awful and can be a health risk to some people. Many filters that employ it include a carbon element to remove the iodine when its job is done. Carbon also gets rid of pesticides, herbicides, heavy metals, and chlorine — but heed a couple of caveats: A few recent studies have shown that in certain situations it’s best to leave a little iodine intact. If you believe your water source is contaminated with sewage, remove the carbon filter. I’ve found that orange juice crystals (ascorbic acid) can help offset the iodine’s nasty taste, but remember to wait a half-hour after filtering before stirring in the flavor booster. In addition, when a carbon element reaches its limit for what is known as adsorbing a chemical, it lets bad stuff through. Always replace the filter and the carbon element according to the manufacturer’s schedule.
A good backcountry water filter weighs less than 20 ounces, is simple to use, and a snap to clean and maintain. At the very least, buy one that removes protozoa and bacteria. Consider the flow rate, too: If it’s slower than a liter per minute, you’ll be very thirsty before your bottle’s full.
All filters eventually will clog — it means they’ve been doing their job. Don’t force water through a filter that’s becoming difficult to pump; you risk injecting a load of microbial nasties into your bottle. Clean it or replace the element. And if the filter has a prefilter to screen out the big stuff, it will give your filter a boost in mileage, which can then top out at about 100 gallons per disposable element. Finally, each filter has its own idiosyncrasies, so read the instructions carefully.
|Bad bugs lurk in the clearest streams: Be sure the filter zaps tiny protozoa and tinier bacteria. Third World-bound? Virus protection is a must.Weight matters: You might be tempted to jettison a filter weighing much more than a pound.|
What to look for
- Good grip and smooth action assure trouble-free pumping.
- Filters clog if they’re doing their job, so it’s a bonus if yours can be cleaned. Ceramic filters can be scrubbed over and over.
- An output hose lets you easily aim purified water, but be sure it doesn’t touch the contaminated source. Some can be fastened directly to a bottle.
- You’ll appreciate a long intake hose when there’s no easy pumping platform right beside the stream.
- A prefilter on the end of the hose keeps grit from prematurely clogging the main element.
1944: Opting for portability over pleasant taste, the U.S. Army returns to using iodine tablets for water purification in the field.
1956: The Katadyn Pocket Filter is introduced as the first truly compact, handheld water filtration system.
Early 1960s-1980s: Annual number of waterborne-disease outbreaks in the U.S. rises more than 330 percent.
1993: Cryptosporidium leaps into the lexicon when more than 400,000 people in Milwaukee, Wisconsin, become ill. Officials discover the waterborne parasite is impervious to chemical treatment, underlining the importance of filters.
1997: The U.S. Army continues to use iodine tablets.