To create the best review of backpacking water filters and treatment methods, we carefully researched and selected the best available models before subjecting them to a series of rigorous tests both in and out of the filed. We polled friends, colleagues, and other backcountry enthusiasts (including Appalachian Trail and Pacific Crest Trail thru-hikers), to see what treatment methods they choose to carry with them in the backcountry for months at a time. Over several seasons of testing on multiple continents and mountain ranges, our team of testers took these filters on multiple overnight camping trips, canyoneering, long rock climbing approaches, trail running, and mountain biking. With this information, we determine their worth in real-world situations, passing on our observations, comparisons, and recommendations to you.
Water Quality
To test and score on water quality, we looked at manufacturer claims for pathogen removal, enlisted third-party SGS Labs to perform water quality tests on each filter, and finally, took into account our own experience using the filters for months. Lab tests involved using a custom “cocktail” mix prepared by SGS (filled with live bacteria, viruses, and inert plastic beads the same size as protozoan cysts). We used each filter as directed and sent water samples back to SGS to evaluate removal rates for each pathogen. After all this, the main difference we found was whether a filter can treat Cryptosporidium (a particularly resilient, hard-to-kill protozoan) and whether it can remove viruses (extra small and hard to catch). Results showed that every filter in our lineup lived up to its claims of pathogen removal.
We also looked at how well systems rid super-dirty water of particulates. These are less of a safety issue, but can make water unpleasant to drink if they aren't removed. We did taste tests and tested each system in both clear and exceptionally turbid sources (water with lots of sediment). We also tested different systems in a “sludge slurry” to see how each fared. These results addressed what we're referring to as our Aesthetic and Health concerns, namely the water quality we perceived in the field as well as what the manufacturer claims each filter protects against, and whether the filters live up to those claims.
Ease of Use
For this metric, we considered all the steps you'd need to perform in order to get water from the source, whether or not the filter was shipped ready to filter on-the-go, or if you'd need to perform the extra steps to set up a gravity filtration system. We note the components that increase the ease of filtration along with those that slow you down. Designs that offer a simple and streamlined process score higher, and those that have a ton of extra parts to keep track of in the field score lower. We also assessed the filtration effort of each filter across different water sources, identifying those that work better in shallow sources and those that require a running stream to fill their reservoir. Some filters feature a ton of versatility, so we tested that too, converting gravity filters into solar showers, hand washing stations, as well as sipping directly from shallow water when we couldn't fill our soft bottle.
Durability and Maintenance
In order to determine the durability of each filter, we noted how well the components held up after each adventure. We noted which models were in need of repair and whether or not any of the components failed after use in the field. For some, we even went through the warranty process with the manufacturer in order to determine the level of support and customer service. We also performed the recommended maintenance on each filter in order to determine whether or not the procedure was cumbersome as well as how it affected the performance of the filter. We also did extensive research online to confirm our results with the experience of other backcountry enthusiasts.
Treatment Time
We time-tested each product by filling a one-liter bottle. We took a minimum of three trials for each and averaged the test results. Some systems offer water on-the-go, so for each of these, it was deemed “instantaneous.” Pump and collapsible squeeze soft bottle filters were also a little subjective, so we had the same tester do all the pumping and squeezing at a similar rate of “pump” to determine the overall effort of each individual filter. This helped us decipher which could intake more water and move it through the filter so we could record the amount of time required to stay hydrated with each model.
Weight and Packability
While each manufacturer identifies a weight for each filter, we didn't take their word for it. Instead, we used a scale to weigh each filter (as well as all the components we'd need to filter water in the backcountry) individually before recording the score and comparing it to the manufacturer's claim. We also packed each product into pockets, backpacks, hydration vests, even climbing harnesses, so that we could determine how easy or cumbersome they were to carry over long distances.
