There are five water treatment methods available for backcountry use. Each removes different threats, weighs differently, and costs differently. The method you choose should match your destination, your group size, and your risk tolerance — not just what everyone else uses.
All five methods compared
| Method | Removes Bacteria | Removes Protozoa | Removes Viruses | Weight | Cost | Best For |
|---|---|---|---|---|---|---|
| Hollow fiber filter (Sawyer Squeeze) | ✓ 99.9999% | ✓ 99.9999% | ✕ | 3oz | $40 + $0 ongoing | US backcountry solo |
| Gravity filter (Platypus GravityWorks) | ✓ | ✓ | ✕ | 6.5oz | $80 + $0 ongoing | Group camping |
| UV treatment (SteriPen Ultra) | ✓ | ✓ | ✓ | 2.4oz | $100 + batteries | International travel |
| Chemical treatment (Aquamira drops) | ✓ | ✓ | ✓ | 0.5oz | $15 + $15/refill | Backup or international |
| Boiling | ✓ | ✓ | ✓ | 0oz (uses stove) | $0 + fuel cost | Camp use with stove |
Hollow fiber squeeze filters: the AT standard
The Sawyer Squeeze is the dominant water treatment on the AT for a simple reason: it is the best tool for the specific threat environment of US backcountry water. North American surface water rarely contains viruses — the primary threats are bacteria (Giardia, Campylobacter) and protozoa (Cryptosporidium). Hollow fiber filters remove both to 99.9999%. At 3oz and $40 with no ongoing consumable cost: it is the obvious choice for solo and small-group US hiking.
The Platypus GravityWorks ($80, 6.5oz) is the right choice when you filter large volumes for a group — hang it and walk away. Katadyn BeFree ($50, 2.3oz) is faster flowing but less versatile.
UV treatment: the international choice
SteriPen Ultra ($100, 2.4oz) uses ultraviolet light to kill bacteria, protozoa, and viruses by disrupting their DNA. It is the right primary treatment for international travel where viral contamination is a real concern (South America, Southeast Asia, developing-world water sources). Not practical for turbid water — requires pre-filtering to remove particles that shield microorganisms from UV light.
Weight and cost profile: lighter than most filters, rechargeable via USB, but dependent on battery/charge and ineffective in turbid water without a pre-filter.
Chemical treatment: the backup
Aquamira drops (chlorine dioxide, $15, 0.5oz) kill bacteria, protozoa, and viruses with 15-30 minutes of contact time. The right backup treatment: if your filter clogs or fails, Aquamira treats water with zero mechanical parts. Carry Aquamira drops on any trip as a 0.5oz insurance policy regardless of your primary treatment method.
Also used by AT hikers in emergencies, high-turbidity water where filters clog quickly, and fast-moving alpine streams where Giardia risk is lower.
Boiling: always available, always reliable
If you carry a stove — and most backpackers do — boiling is always available. One minute at a rolling boil (3 minutes above 6,500 feet) kills all pathogens including viruses. Cost: fuel. Limitation: must wait for water to cool before drinking. Practical for cooking and camp hot drinks where boiling happens anyway.
The recommended system for AT hiking
Backup: Aquamira drops ($15) in the first aid kit.
Combined weight: 3.5oz. Combined cost: $55. Covers all realistic AT water threats.