The Best Water Filters for Backpacking for 2019
We researched the best water filters and aggregated that data. Here's our findings.
After checking dozens of review sites and hundreds of customer reviews - and considering our own experiences - we put together a list of stand-out water filters for backpacking. If you’re hiking solo or on a trip where each person takes care of their own water, we think the Sawyer Squeeze has the speed-to-weight ratio that works best for most folks. Got a group to care for? We like the Platypus GravityWorks, which can filter four liters in four minutes with minimal fuss. For international travel, the upgrade-pick MSR Guardian filters out viruses and cleans itself with the press of a hand-pump.
THE BEST WATER FILTER FOR MOST PEOPLE: Sawyer Squeeze
The Sawyer Squeeze is a tried and tested filter that has an excellent speed-to-weight ratio. The number of high-quality and high-star user reviews at Amazon, REI, and Backcountry speak to how well the Sawyer Squeeze is regarded. It also made the best-of lists on four out of the seven sites we aggregated from.
Weighing 2.7 ounces for the filter - 5.1 ounces total for the filter and two provided bags - the speed of this filter can’t be beat. Though you can filter from the dirty bags the Squeeze comes with into a clean bottle if you like, we prefer to drink straight through the sports top, getting our fix instantly. And with a lifetime warranty - and a promise of filtering a million gallons over the course of a lifetime - the cheapest filter over time that we reviewed, providing clean water at under a penny per liter.
The Sawyer Squeeze’s absolute 0.1-micron hollow fibers remove protozoa, bacteria, and cysts from the water it filters. This means you’re covered for things like cryptosporidium and giardia, which are the most common worries for US and Canadian travel. If you’re traveling in a place where sewage is more of a concern, you’ll want a purifier like the MSR Guardian or the SteriPen Ultra, to make sure you get viruses out of the water as well.
If you’re more of an on-the-go water drinker, drinking from a hydration hose only requires a little alteration to your hose and filter. Take the sports top off the Sawyer and attach the inline pieces to both sides. Then, cut your hose, and attach the cut ends to either side of your filter, with the “Clean” side facing towards your bite valve. Then, voila: you can add dirty water to your hydration bladder, suck it through the filter, and drink clean water. Our testers didn’t notice a reduced flow. And at night, that same system can be hung as a gravity filter. Just pop off the bite valve and use the system to collect clean water into a bottle or cooking pot.
Still, the Squeeze has some issues, many related to the bags that come with the filter. These bags are intended to store and help filter dirty water, and they’re collapsible. We’ve noticed - as have both Switchback Travel and other user reviews - that because they have a small opening, they’re hard to use when collecting water from lakes and other stillwater sources. (It takes time, but skimming a bag across the surface until it has enough water in it to sink does the trick.) We’ve all also seen the bags break down easily under the pressure of the squeezing, so if you’re using them, it’s necessary to carry an extra to be sure you’re not left without. We prefer to attach the Squeeze to a SmartWater bottle or Evernew hydration bladder to eliminate these problems altogether. (Watch your gasket, though - this o-shaped ring makes a seal with the bladder or bottle, and is prone to falling out of the filter if you’re not careful. If this happens, Sawyer will replace it or you can save on shipping by replacing the ring at a hardware store for fifty cents.)
Other issues are related to the squeezing part of the Sawyer’s filtration process. Clever Hiker noted that “the squeezing process can become rather tedious over time”, making the filter impractical for large groups (and if you’ve got a large group, we’ve got you with a group recommendation). And because you don’t necessarily squeeze all the water out of the filter when you’re done filtering, Outdoor Gear Lab notes that the Squeeze can leak dirty water if you’re not paying attention. Still, a little forethought and care - or using it inline as a part of a hydration pack or gravity system, like we talked about - solves both of these issues, so the Sawyer Squeeze is still the best water filter for most folks headed outside.
As a side note, some might prefer the Sawyer Mini for its reduced size, weight, and price, but we agree with Clever Hiker’s analysis that "the cost/weight savings aren’t quite worth the reduced flow rate over time", particularly for long trips. If it’s between carrying an extra ounce and constantly cleaning the filter when (not if) it clogs, we’ll take the extra ounce, thanks.
Best for Group or Family Outings: Platypus GravityWorks 4L
Occupying the #1 slot at both Outdoor Gear Lab and Switchback Travel, the Platypus Gravity Works 4L involves the least amount of work among all the filters listed. All you do is fill the “Dirty” bag, hang it higher than the “Clean” bag, and open up the line to send a liter per minute into the “Clean” bag below. It’s that simple. The system is heavy in the pack and on the wallet - over twice the weight and price of the Sawyer Squeeze - but Switchback Travel still calls it “worth the cost and bulk.” And with a lifetime of 1500 liters per filter, the entire system costs about $0.08 per liter.
The GravityWorks has a 0.2-micron filter, which means you’re safe from the major microscopic concerns in the US and Canada. If you’re traveling outside of the US or Canada in a place where sewage contamination is more of a concern, you’ll want a purifier like the MSR Guardian or the SteriPen Ultra, to make sure those viruses are eradicated as well.
Outdoor Gear Lab notes that the GravityWorks system is fast, great for large groups, light for what you get, and “requires little to no maintenance.” Customer reviews across Amazon, REI, and Backcountry loved this system for the same reasons. And that maintenance they mention? All you have to do to is keep some water in the “Clean” bag after filtering, and raise it higher than the dirty bag to send the water back through the filter.
We interviewed desert adventurist Sirena Dufault who likes that unlike other systems, the Platypus GravityWorks could process large amounts of water (a necessity when finding water may be a once per day affair—or even less frequent). Although she often travels solo, she values its ability to handle silty water and to maintain in the field easily. She also uses, “the [clean and dirty] bags for additional water storage in the desert and as backups in case there’s a problem or [I] lose a container.”
The GravityWorks is not a perfect system. Complaints abound about the bags. REI reviewers warn the hang grommets fall apart. “The first few liters [...] taste like plastic” was a common complaint on Amazon reviews. Customers on both sites complain that only one of the bags dries easily. A bigger argument against the GravityWorks is that the Sawyer Squeeze can also act as a gravity filter at less than half the cost, while also working as an on-the-go filter. Still, these complaints feel nitpicky for the speed and ease with which the Platypus GravityWorks provides a lot of water for a little effort.
International Travel Upgrade Pick: MSR Guardian
If you’re headed backpacking in a country where viruses lurk in the groundwater, you’ll want to have the MSR Guardian with you. Where 0.2-micron filters like the Platypus GravityWorks are big enough for viruses to pass through, the MSR Guardian’s 0.02-micron, military-grade filter catches everything. It also uses about ten percent of the water it filters to backflush itself, essentially eliminating the need to clean this filter by hand. MSR drop-tested it from six feet onto concrete, and freeze-tested it to make sure the filter doesn’t break in freezing weather. And, even with hand pumping, it filters a liter of water in about 45 seconds. But you pay for what you get: the MSR Guardian is the heaviest of our reviewed filters at 22 ounces, and is five times the price of systems like the Sawyer Squeeze. But with a lifetime of 10,000 liters, the $0.03 price per liter is among the lowest of water filters reviewed.
Both Outdoor Gear Lab and Switchback Travel rave about the quality and performance of the MSR Guardian. And it does seem pretty easy to use: toss the tubing into the water, set the filter on top of your bottle, and hand-pump clean water into your bottle. Outdoor Gear Lab even recommends it for groups, despite the hand-pumping - though maybe they spread the work out among group members. Customer reviews are consistently high - right around 4.5 out of 5 stars on Amazon, REI, and Backcountry - although they’re less exuberant than we were expecting. We think that stems from high expectations, given the high promises and high price. Many reviewers express disappointment that the MSR Guardian doesn’t perform better in silty water, as reviewers at all three sites report clogs in silty water. But it’s a filter, not a miracle worker: consider pre-filtering your water, or at least gathering it into a bottle or bucket and letting it settle a bit before filtering off the top. If you do have issues, though, a Backcountry reviewer reports that MSR’s customer service is on point and ready to help.
Also, maybe you noticed, maybe you didn't, but the MSR Guardian is the only hand pump filtration and purification system that made the cut for us. Weird? Maybe. A number of the other professional review sites recommended the Katadyn Hiker Pro, another hand-pump filter, as a good option. But having walked tens of thousands of miles, we think hand pumps are laborious, heavy, and prone to breaking, and generally wouldn't recommend them - but the durability and features the Guardian offers won us over.
Best Filter for Short Trips: Katadyn BeFree 1L
The filter with the most mentions across all professional review sites, the Katadyn BeFree is a filter that’s essentially the lid on a collapsible water bottle. The lightest filter at 2.3 ounces, and one of the most collapsible, it filters a liter just about as fast as you can drink it. At 0.1 microns, this filters out everything but viruses, and at a lifetime of 1,000 liters, the price per liter is about $0.05. While we reviewed the 1-liter version, 0.6- and 3-liter versions also exist, if you need more or less water for your excursions.
Customer reviews that have loved the BeFree have taken it out on shorter backpacking trips or day hikes. Like Clever Hiker, we questioned the use of this bottle for longer backpacking trips: "The soft bottle of the BeFree isn’t built to withstand squeeze filtering 4-6 liters per day and hauling water from one source to the next. Also, the filtration unit on the BeFree is relatively small, which impacts its flow rate over time faster than we’d prefer." Outdoor Gear Lab and Backpacker also reported leaks, and while those leaks were easy to fix, this makes us nervous about its use for longer trips. Still, for shorter outings with lots of water, the Katadyn BeFree is a handy, lightweight filter.
Note: we used the BeFree filter component with a home-made system that uses a stuff sack and medical tubing. This system isn’t commercially available, but solved the capacity issues that make the Katadyn BeFree system our recommendation for short trips only.
Best Filter for Lakes and Puddles: MSR Trailshot
It feels so good to come across a burbling stream with a clear, strong flow, knowing that’s what you’ll be drinking shortly. It feels less good to come up to a stagnant puddle and know that’s your only water source for the next five miles. Enter the MSR Trailshot. Just place the plastic intake in the source, work the miniaturized hand pump by squeezing your fingers, and you’re filtering comfortably from still water sources like puddles, lakes, and even cow troughs. If you’re worried about leaks from the Katadyn BeFree, but are still looking for something for shorter trips or trail running that’s lightweight, the MSR Trailshot might be for you.
Like most the other filters in the review, the Trailshot takes about a minute to filter a liter of water through the 0.2-micron filter. You wouldn’t want to use it in places where sewage might be in the water, but it’s good for filtering out the nasties found in the US and Canada. With a lifespan of 2,000 liters, it’s one of the cheapest filters over time at $0.03 per liter. And while it’s not the lightest filter in the review at 5.6 ounces, it has one of the smallest packed sizes. Backpacker notes that it doesn’t change the taste of gross water and doesn’t do well with silt, but Gear Junkie elaborates that you simply shake it to clean it.
While the Trailshot is generally well-liked, REI reviewers that disliked it complained of a slow flow rate. Many users across Amazon and REI reported the distinctive taste of plastic initially, and many recommended running lime or lemon water through the system to help clear up that taste. Others agree with Switchback Travel, suggesting that this is not a filter to be used for groups - the Platypus GravityWorks is a much better system if you’ve got a lot of people. Still, if you don’t want to wrestle with hydration bladders when filtering out of small, shallow puddles, check out the MSR Trailshot.
International Filter of Subtlety: Grayl Ultralight Purifier Bottle
While less practical for trail backpacking, if you’re backpacking the world the Grayl Ultralight Purifier Bottle is definitely worth a look. While taller and skinnier than a Nalgene and relatively heavy at 10.9 ounces, this filter wins for subtlety, as it looks much like a coffee cup. It functions much like a french press - pour dirty water in, press the filter down slowly, and let the electroadsorption (read: bitty electrical charge) destroy protozoa, bacteria, and viruses. But it only filters 16 ounces at a time, and dependent on how you press, this is likely the slowest filter in the review. It’s also the most expensive when it comes to price per liter filtered; as each replaceable filter only goes for 150 liters, the price per liter shakes out to $0.40 per liter.
Adventure Junkies notes that it’s impossible to tell when you need to change the filter - you have to give it your best guess, which is concerning (although Grayl’s website notes that as the cartridge life nears its endpoint, press time increases). Backpacker says it produced the best-tasting water in their review, and while Clever Hiker didn’t like it for longer backpacking on trails, they called it a “good choice for city travel and quick backpacking trips.” One Backcountry reviewer called their review “International Travelers Delight,” but Amazon reviewers were more focused on how durable the bottle felt. Across Amazon, REI, and Backcountry, all reviewers had feelings about how easy or hard the filter was to push down, so your experience will likely vary as well. Still, we think it’s super cool, and will likely take it with us on our next sightseeing trip out of the country.
The Best Water Purified for Techies: Steripen Ultra
It’s not exactly a filter per se, but we like the rechargeable Steripen Ultra for its quick and easy use. It’s a purifier like both the MSR Guardian and Grayl Ultralight Purifier Bottle - so it removes viruses as well as protozoa and bacteria. The advantage? The only effort you put in is turning it on, sticking it in your bottle, flipping the bottle upside down, and swirling for 90 seconds. Sure, that’s longer than the other filters in this review, but at 6 ounces including the charging cable, it’s the lightest purifier in the review. With a lifetime of 8000 liters, or 50 liters per charge, the price is about $0.01 per liter - one of the cheapest filters in our review. The catch? It’s ineffective in murky water, as Clever Hiker notes, so you’ll definitely need to pre-filter if you want to make sure you’re in the clear. It’s also dependent on its battery, so if that goes, so does your ability to purify your water.
Amazon reviewers seem to primarily use this model for international travel, and several complain of quality control issues where their SteriPen did not work out of the box. An REI reviewer reminded us that as a battery-powered device, it’s less apt to work correctly in the cold, and the cold will sap the battery power more rapidly. Always make sure to test any filter before you go out, just in case, and protect it from cold nights by keeping it with you in your sleeping bag. For the price and the effectiveness, the SteriPen Ultra is a worthy buy.