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How to Use a Squeeze Water Filter

Set up, use, backflush, and store a squeeze-type water filter, plus why you still disinfect after filtering. Plain steps from CDC and Sawyer guidance.

4 min read · Crew role: Cookie · Shelf: Water

What it's for

A squeeze filter turns creek, pond, or questionable tap water into water you can drink, a pouch at a time. It's light, it needs no power, and it works fast. It's the Cookie's everyday tool for keeping the outfit watered when the jugs run low.

One thing to know up front: the CDC says portable filters do not remove viruses. To remove bacteria a filter needs an absolute pore size of 0.3 micron or smaller, and 1 micron or smaller for parasites like Giardia and Cryptosporidium. So after filtering, the CDC recommends adding a chemical disinfectant to catch what the filter can't. Read your filter's box for its rated pore size.

Before you need it (practice)

  • Read your filter's manual. Steps differ by brand. The Sawyer steps below are for Sawyer filters; follow your own maker's instructions for anything else.
  • Backflush it once before first use. Sawyer recommends backwashing before first use, when flow slows, before long storage, and when you start using it again.
  • Do a backyard run. Fill the pouch from the garden hose, squeeze a liter into your canteen, and time it. You'll learn how hard to squeeze without bursting the pouch.
  • Label your containers. Mark one "DIRTY" and one "CLEAN" with a permanent marker so nobody mixes them up in the dark.

Step by step

  1. Pick the clearest water you can. If it's cloudy, let it settle or pour it through a clean cloth or coffee filter first (CDC). Sawyer notes muddy water means backflushing as often as every 10 gallons.
  2. Fill the dirty pouch or collapsible container.
  3. Screw the filter on snug, not cranked. Sawyer notes that overtightening can unseat the washer and cause leaks.
  4. Squeeze into your clean canteen or bottle.
  5. Disinfect the filtered water with tablets or bleach per the label (see our purification guide). CDC: filters don't stop viruses.
  6. Drink, then repeat.

Common mistakes

  • Backflushing with dirty water. Sawyer says don't. If it happens, run at least a gallon through and dump it before drinking.
  • Letting a wet filter freeze. Sawyer rates its 0.1-micron filters for 32-140°F. Once wet, freezing can damage the fibers with no way to tell, so Sawyer says replace a filter you suspect froze. On cold nights, sleep with it in your bag; in the day, keep it in an inside pocket. An unused, never-wet filter isn't harmed by freezing.
  • Treating filtered water as finished. Add the disinfectant step.
  • Squeezing so hard the pouch bursts. Sawyer says its pouches are made to burst before the force would damage the filter. A burst pouch means ease up and backflush.
  • Trying to filter out fuel or chemicals. The CDC says you can't make water with fuel or toxic chemicals safe by filtering, boiling, or disinfecting. Find another source.

Care & storage

  • Backflush forcefully with clean water using the plunger until water runs clear and easy (Sawyer). With clear sources this may be rare; with muddy water it can be every 10 gallons.
  • Slow even after backflushing? Sawyer suggests soaking in hot (not scalding) water, then backflushing; for mineral buildup, a short vinegar soak first.
  • Before long storage: backflush, sanitize per the manual (Sawyer describes a dilute fragrance-free bleach backflush), let it dry, and store it somewhere that never freezes. Not the truck in January.
  • Wake it up after storage with a backflush to re-wet the fibers.

Related gear

Sources

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