The Time I Drank Unfiltered Water (Don't)
Let me start with a cautionary tale. Early in my hiking career, I was on a day hike to Snow Lake near Snoqualmie Pass. Hot day, I ran out of water, and the lake looked crystal clear. I told myself "mountain water is clean" and drank straight from the source. Two weeks later, I had giardia. If you've never had giardia, imagine the worst stomach flu of your life lasting 10 days, with cramps so bad you can't stand up straight. I lost 8 pounds. My doctor was not sympathetic. "You drank unfiltered backcountry water? Really?"
Clear water means nothing. Giardia cysts are invisible. Cryptosporidium is invisible. Animal waste from wildlife you never see contaminates even the most pristine-looking alpine streams. Filter your water. Every time. No exceptions. Now let me tell you which filters are actually worth buying.
Sawyer Squeeze — The One I Use
The Sawyer Squeeze has been the default backpacking water filter for years, and for good reason. It weighs 3 oz (85g), costs $35, filters down to 0.1 microns (removing 99.99999% of bacteria and 99.9999% of protozoa), and has a rated lifespan of 100,000 gallons. You could filter water every day for the rest of your life and never need a replacement.
I pair mine with a CNOC Vecto 2L dirty water bag ($15), which has a wide opening for scooping from shallow sources and threads directly onto the Sawyer. At camp, I hang the CNOC bag from a tree branch and let gravity feed water through the filter into a clean Smartwater bottle below — hands-free filtering while I set up my tent. On the go, I squeeze directly from the CNOC bag through the filter and drink from the output. The whole system weighs about 5 oz, costs $50, and has been my primary water treatment for three seasons.
Where the Sawyer falls short: flow rate degrades over time. A brand-new Sawyer Squeeze flows fast. After a few trips, especially in silty or tannin-rich water, the hollow-fiber membrane clogs and the flow rate drops to a frustrating trickle. Backflushing with the included syringe helps — I do it after every trip — but it never fully restores the original flow. I also carry a small coupler that lets me backflush with a Smartwater bottle in the field if the filter clogs mid-trip, which has saved me twice.
The other major caveat: freezing kills the Sawyer. If water inside the hollow fibers freezes, the expanding ice cracks the fibers and the filter silently fails — it still flows, but bacteria pass right through. On cold-weather trips, I sleep with my Sawyer inside my sleeping bag to prevent freezing. If you have any doubt whether your Sawyer has frozen, replace it. A $35 filter is not worth a case of giardia.
Best for: Most backpackers, most of the time. The gold standard for a reason.
Katadyn BeFree 1.0L — Fastest Flow
The Katadyn BeFree was my attempt to solve the Sawyer's flow rate problem, and it succeeded — at a cost. The BeFree uses a hollow-fiber membrane similar to the Sawyer, but with a different design that delivers dramatically faster flow rates. Fresh out of the box, it flows about 3x faster than the Sawyer. You can fill a liter in about 30 seconds of gentle squeezing. It weighs 2 oz (59g) and integrates directly into a 1L soft flask, making it an all-in-one system with no separate bags or hoses.
I took the BeFree on a fast-and-light trip through the Pasayten Wilderness, and the speed was revelatory. At water sources, I could filter, drink, and be moving again in under a minute. With the Sawyer, the same process takes 3-4 minutes. On a big-mile day where you hit 8-10 water sources, that time savings adds up.
The problem: durability. After about 4 months of regular use, the soft flask started cracking at the connection point where it threads onto the filter. The flask is proprietary — you can't use a standard Smartwater bottle — and a replacement costs $15. I've also found the BeFree harder to backflush effectively than the Sawyer, and the flow rate degrades faster in silty water. On a trip through the Wind River Range where I was filtering from glacial melt (basically liquid rock dust), the BeFree clogged to near-zero flow within two days. The Sawyer would have survived longer with its backflush syringe.
I still recommend the BeFree for specific use cases — day hikes, fastpacking, and trips where you're filtering from clean, clear sources. But for multi-day backpacking trips where reliability matters more than speed, the Sawyer's simplicity and serviceability make it the safer choice.
Best for: Day hikers, fastpackers, and anyone who values speed at water sources. Best on clean, clear water sources where clogging isn't a major concern.
Platypus GravityWorks 4.0L — Best for Groups
If you're backpacking with a partner or a group, the Platypus GravityWorks 4.0L changes the water game entirely. Hang the dirty bag, connect the hose to the clean bag, and walk away. Gravity does the filtering. Four liters in about 5-6 minutes with zero effort. When the clean bag is full, you have 4 liters of filtered water that you can pour into individual bottles — enough for two hikers to top off and cook dinner.
I use the GravityWorks on any trip with my wife or hiking group. The setup takes about 2 minutes: fill the dirty bag at a stream, find a branch or rock ledge to hang it from (the bag needs to be 3-4 feet above the clean bag for gravity to work), and connect the hose. While the water filters, we set up camp, change clothes, start organizing food — it's completely passive. With a Sawyer Squeeze, one person would be standing at the water source squeezing for 15 minutes while everyone else waits.
The system weighs 11.5 oz (326g) and costs about $110. That's significantly heavier and more expensive than the Sawyer, which is why I don't bring it on solo trips. But split between two people, each person carries about 6 oz of filter system that processes water faster than any squeeze filter on the market. The flow rate does degrade with use, and the cartridge is replaceable — I swap mine out after about a year of regular use, which costs about $40.
One thing I love about the GravityWorks: the clean bag doubles as a camp water reservoir. I hang it from a tree near the cook area and pour from the hose like a tap. No more trips back to the stream every time someone wants a drink.
Best for: Couples and groups. Car campers who want the easiest possible water filtering experience. Base camp setups where you want a lot of clean water available without effort.
Honorable Mention: Chemical Treatment
I always carry Aquamira drops as a backup, even when I have a filter. Aquamira uses chlorine dioxide to kill bacteria, viruses (which filters don't catch — though viruses are rarely a concern in North American backcountry), and protozoa. It weighs 3 oz for the two-bottle set and treats about 30 gallons. The process takes 30 minutes (mix the drops, add to water, wait), which is its main drawback — you need to plan ahead.
Chemical treatment is my backup if my filter breaks or freezes. It's also what I bring on winter trips where freezing concerns make hollow-fiber filters risky. The drops don't freeze at typical winter backpacking temperatures, and they work in any water temperature (though they take longer in cold water — up to 4 hours in near-freezing conditions).
My Actual Setup
Solo trips: Sawyer Squeeze + CNOC Vecto 2L bag + Aquamira backup. Total weight: 8 oz. Total cost: $60.
Group trips: Platypus GravityWorks 4.0L + Aquamira backup. One system for the whole group.
Day hikes: Katadyn BeFree when I expect to filter on trail, or just carry enough water from home if sources are limited.
Any of these systems will keep you safe. The Sawyer is the best all-around value and the one I'd recommend if you're buying your first filter. Just remember to backflush it, never let it freeze, and never drink unfiltered backcountry water no matter how clear it looks. Trust me on that last one.
