What's in Backcountry Water
Three threats: protozoa (Giardia, Crypto — 1-15μm), bacteria (E. coli — 0.2-5μm), viruses (Noro, Hep A — 0.02-0.1μm). In North America, viruses are rare — protozoa and bacteria are the concern.
Filter vs Purifier
Filter: removes protozoa + bacteria (sufficient for N. American backcountry). Purifier: also removes viruses (needed for international travel).
Squeeze Filters: Best All-Around
Sawyer Squeeze
0.1μm absolute, 3 oz, rated 100,000 gallons. Most popular backpacking filter — backflushable, nearly indestructible.
Katadyn BeFree 1.0L
0.1μm, 2 oz, 2L/min flow when new. Fastest squeeze filter — great for trail running.
UV Purifiers
SteriPEN Ultra
UV-C purification (kills viruses too), 5 oz, rechargeable, 90-sec per liter. Best for international travel.
Chemical: Ultralight Backup
Aquamira Water Treatment Drops
Chlorine dioxide, 1 oz for 30 gallons. 15-30 min treatment time.
Katadyn Micropur MP1 Tablets
$14/30 Check Price on Amazon
Chlorine dioxide tablets. 15-min bacteria, 4-hour Crypto.
Sources
- CDC. "Water Treatment for Backcountry & Travel Use." 2024.
- EPA. "Guide Standard for Testing Microbiological Purifiers." 2023.
- Outdoor Gear Lab. "Best Backpacking Water Filters 2025."