Safe drinking water remains essential for backcountry travel, but carrying sufficient water for multi-day trips proves impractical given its weight. Water purification methods allow hikers to treat water from natural sources, reducing pack weight while ensuring adequate hydration throughout extended wilderness adventures.
Understanding Water Contaminants
Backcountry water sources may contain bacteria, viruses, protozoa, and chemical contaminants. Bacteria like E. coli and Salmonella cause gastrointestinal illness. Protozoa including Giardia and Cryptosporidium resist some treatment methods and cause severe intestinal problems. Viruses rarely present concerns in North American backcountry but become important considerations for international travel.
Chemical contaminants from agricultural runoff, mining operations, and natural mineral deposits require specialized filtration beyond what standard backcountry treatment provides. Research your hiking destination to identify any known chemical contamination concerns.
Filtration Methods
Mechanical filters physically remove contaminants by forcing water through filter media. Pump filters like the Katadyn Hiker and MSR MiniWorks provide reliable treatment but require manual effort and add weight. Gravity filters from Platypus and Sawyer hang from trees and filter large volumes hands-free, making them ideal for group camping.
Squeeze filters offer the lightest weight option for solo hikers. The Sawyer Squeeze and Sawyer Micro filter thousands of liters before replacement. These inline filters attach directly to water bottles or hydration bladders for convenient use throughout the day.
Filter pore size determines what contaminants are removed. Filters rated at 0.2 microns or smaller remove bacteria and protozoa effectively. Hollow fiber filters can be cleaned by backflushing, extending their usable life significantly.
Chemical Treatment
Chemical treatments kill pathogens through oxidation or other chemical reactions. Chlorine dioxide tablets like Aquamira and Potable Aqua effectively treat bacteria, viruses, and most protozoa. Treatment times vary from fifteen minutes to four hours depending on water temperature and contamination level.
Iodine tablets provide backup treatment but leave unpleasant taste and are not recommended for pregnant women or people with thyroid conditions. Chemical treatments work best in combination with filtering to remove sediment that can shield organisms from chemical contact.
Ultraviolet Treatment
UV purifiers like the SteriPEN destroy pathogens by disrupting their DNA. UV treatment works quickly, typically requiring only ninety seconds per liter. However, UV treatment requires clear water because sediment blocks UV penetration. Pre-filter cloudy water or allow sediment to settle before UV treatment.
UV devices require batteries or charging, adding potential failure points in remote areas. Carry backup treatment methods when relying primarily on UV purification.
Boiling Water
Boiling remains the most reliable purification method, killing all pathogens including viruses and Cryptosporidium cysts. Bring water to a rolling boil for one minute at sea level, adding one minute for each thousand feet of elevation above five thousand feet.
Boiling requires fuel, time, and produces hot water that must cool before drinking. Most hikers reserve boiling for cooking rather than primary drinking water treatment, but it provides reliable backup when other methods fail.
Choosing Water Sources
Source selection affects treatment difficulty and safety. Flowing water from streams generally contains fewer contaminants than stagnant ponds. Collect water upstream from trails, campsites, and grazing areas to minimize contamination from human and animal activity.
Spring sources emerging directly from the ground often provide the cleanest natural water. However, treat all backcountry water regardless of how clean it appears. Invisible pathogens cause most waterborne illness, not visible contamination.
Hydration Strategy
Plan water carries based on source availability along your route. In well-watered areas, carry one to two liters and refill frequently. In dry terrain, cache water or carry four or more liters between reliable sources. Dehydration impairs judgment and physical performance, so err on the side of carrying extra water when uncertain about source reliability.
