I've been backpacking several times borrowing other people's equipment, but now I'm getting ready for a trip in the Adirondacks and need to get some more gear of my own. Is it true that viruses are primarily a problem in the water in other countries? What viruses are potentially problematic in the U.S., and what illness do they cause? Adina Syracuse, New York
So, what to do? Always filter water, of course. Beyond that, my policy is to consider its source. The closer I am to where the water got its starta glacier, a snowfield, a springthe less concerned I am about viruses. I don't think the Adirondacks area poses a particular risk, but its high usage by humans might warrant caution. If you are concerned, then it's prudent to treat the water with a virus-killing agent such as SweetWater Purifier ($9; www.msrcorp.com), a chlorine-based agent that kills just about anything that wiggles... in your water, that is.
Otherwise, you might want to consider one of Katadyn's filtration pumps, albeit a little more costly and bulky, but able to deliver quick, potable water on the go. The 11-ounce Katadyn Hiker ($60; www.katadyn.com) is a compact system that delivers about a liter a minute without too much effortgreat if you're in a group or don't fancy the aftertaste of some of the chemical treatments.
Get more water-filtration advice in Outside's 2004 Buyer's Guide.