I live near a river, and it's nice to be able to cary this in my fanny pack on any day hike for emergencies. I plan to get several!

Take it from a guy who drinks copious amounts of water, this filter is the king of survival items. "Survivorman" Les Stroud has, in fact, contracted giardia in his survival adventures. Les is a teacher who's lessons are sometimes taught at the expense of his health. His lesson? Don't take chances with parasites or bacteria. This handy little filter fits in your back pocket and will filter up to 20 gallons, enough to sustain one person for days to weeks. I keep one in the car, one at home, and I never hike anywhere without one.