Water Purification

When to use this

Any water source that isn't a sealed municipal supply. "Clear" does not mean "clean."

• Any trip where you're sourcing water from streams, lakes, or springs
• Emergency backup when camp water runs out
• Filtering well water at primitive sites

See it done

What you need

• Filter method: a squeeze filter (Sawyer Squeeze, Platypus QuickDraw)
• Chemical method: iodine tablets or Aquatabs (chlorine dioxide)
• Boil method: a pot and a heat source
• A collection vessel (water bottle or soft flask)

Step by step

1. 1.Collect water from the fastest-moving, clearest part of the source — upstream of any camp or trail crossing.
2. 2.Filter method: fill the dirty bag, screw on the filter, squeeze into a clean vessel. Fast (1 liter in under a minute) and tastes natural.
3. 3.Chemical method: drop one tablet per liter. Wait 30 minutes before drinking (4 hours for Giardia-safe treatment with chlorine dioxide). Best as backup.
4. 4.Boil method: bring water to a rolling boil for 1 minute (3 minutes above 6,500 ft). Let cool. Most reliable — kills everything. Slowest.
5. 5.For turbid (murky) water: pre-filter through a bandana into a separate vessel before using your main filter.

Pro tips

• A Sawyer Squeeze weighs 3 oz and lasts a lifetime with backflushing. It's the easiest upgrade from chemical tabs.
• Keep your dirty and clean bags on opposite sides of your pack. Cross-contamination defeats the purpose.
• At a car campsite with a hose bib: still verify it's potable — some non-potable taps exist at trailheads.

Common mistakes

• Touching the dirty bag threads to the clean vessel neck — this bypasses the filter entirely.
• Not backflushing the Sawyer filter after use. It clogs and flow rate drops to unusable.
• Assuming fast-moving water is safe. Giardia cysts float and thrive in any natural source.