Water is the stuff of life, and when you’re exploring in the backcountry, having access to clean H2O is vital. For that, you need a portable water filter. Unlike many home units, systems designed for backpacking, camping, and hiking are equipped to remove bacteria, protozoa, and sometimes viruses, too. They also sift out particulate matter and can neutralize funky tastes, so you can chug with confidence.
Read quick reviews of five top-performing backpacking water filters, then keep scrolling for buying and maintenance advice along with full reviews of these and other models we tested.
The Difference Between Filters and Purifiers (And How They Work)
Water treatment is often lumped into one category—filters—but there are also purifiers, which remove viruses, too. On the surface, more protection sounds better, but the level you need depends on where you’re going. Water-borne viruses aren’t a threat in the U.S., Canada, parts of Europe, and Australia, so a filter is just fine. If you’ll be traveling elsewhere overseas, pack a purifier.
Despite the difference in their capabilities, the way filters and purifiers work is similar. They push water through a hollow fiber or ceramic element with very small pores so the liquid can escape but bacteria, protozoa, and other harmful contaminants can’t. These pores typically measure 0.2 micron for filters and 0.01 micron for purifiers. (For comparison, a human hair measures 25 microns or more.) Many filters and purifiers, including the majority on this list, have hollow-fiber elements. Compared to their ceramic counterparts, these elements are cheaper to produce (saving you money) but have shorter lifespans, requiring replacement sooner. Sometimes companies pair hollow-fiber or ceramic filters with activated carbon, which neutralizes tastes and odors by trapping contaminants to its surface. However, like other adsorptive elements, carbon has a shorter lifespan and is especially taxed by sediment-rich water.
Water can also be purified by UV light or chemicals, which kill microorganisms or block their ability to reproduce, making the treated liquid safe to drink. Neither of these methods remove particulate matter though, so first, you’ll want to filter water (either with a system or with a piece of fabric) or let it rest so you can separate out the clear stuff. Because of their time-consuming nature, these methods are far less common, except in cold-weather environments. Freezing temperatures don’t impair the effectiveness of UV light or chemical treatment unlike the damage it causes to hollow fiber and ceramic elements.
Types of Treatment Systems
Filters and purifiers have mechanical differences, too. Pumps and gravity systems are best for treating a large volume of water, whereas bottles, in-line filters, and straws are better for personal hydration.
Care and Maintenance
Be smart about using your filter or purifier when you’re in the field. Look for the cleanest water source available, and don’t throw or drop the filter, which can damage the element. Minimize cross-contamination by storing dirty and clean parts separately and washing or sanitizing your hands after touching untreated water. You should also regularly backwash your system’s filter to clear build-up. For hollow-fiber systems, use a syringe, drinking tube, or outlet hose to force clean water through the filter in the opposite direction as water is normally dispensed. Ceramic elements should be removed from their housing, wiped down, and rinsed with clean water. In cold conditions, put your system in a Ziploc bag and place that at the foot of your sleeping bag to keep it from freezing. We always pack a chemical treatment as a backup, but when in doubt, boiling water will rid it of harmful microorganisms.
Back at home, disinfect your whole hydration setup before storing it. Your kit will come with specific instructions, but remember to never use soap on the element as this will damage it. In most cases, you’ll know it’s time to replace your filtration element when your system gets harder to use and backwashing doesn’t improve speed much.
How We Tested
To find the best backpacking water filters and purifiers, we evaluated the speed, ease of use and maintenance, weight, element lifespan, and price of the contenders. We recorded how long each model took to treat one liter of water from the same creek, repeated that test two more times, and averaged the three results to calculate our average treatment time. Contenders earned extra points if we noticed a significant improvement in clarity over the unfiltered liquid. After that, we weighed the systems with their accessories and any carrying bags to see how they measured when the filters had retained some water. We’ve cleaned these treatment options and used them in the field like you will. We’ll keep using them, too, so we can report how they stack up over time.
Weight: 14.4 oz. | Average Treatment Time: 43 seconds | Element Lifespan: 750 L
Katadyn’s Hiker looks unassuming, but this filter pump is a workhorse. The pleated glass-fiber filtering element has a greater surface area than ceramic cartridges to allow for increased water flow. In our speed comparison, it was only bested by the Grayl GeoPress, but unlike that bottle, it doesn’t limit the amount of water you can treat in one sitting. That speed comes with another advantage, too: We were less likely to fatigue when refilling our practically empty hydration reservoir. This reasonably priced model also scored points because it comes with a plastic pouch with an easy-to-use sliding lock for storing the output hose and removable bottle adapter. It’s a thoughtful addition that lowers the risk of cross-contamination. As for its shortcomings, the filter’s 750-liter lifespan is below average, and we’ve noticed some small scratches on the pump after propping it on rocky surfaces. The damage is only cosmetic, though, so we don’t find it a major concern. With the Hiker, you’ll be restocked and back on the trail in hardly any time at all.
—EASIEST-TO-CLEAN PUMP FILTER—
MSR MiniWorks EX Microfilter
Weight: 1 lb. 2.8 oz. | Average Treatment Time: 1:10 | Element Lifespan: 2,000 L
MiniWorks EX Microfilter
Tubes from treatment gadgets and hydration reservoirs are a pain to clean, and MSR minimizes that headache by only having an input hose on the MiniWorks EX (and its other pump filters and purifiers). Clean water flows from the bottom of the unit, which screws onto wide-mouth water bottles. You can also attach it to hydration reservoirs, but only the ones that MSR makes. The MiniWorks ranked near the top of our speed test and further impressed us because the treated water was visibly clearer than the original stuff. The full-size handle, positioned on the side of the unit, provided the best grip among the pump filters we’ve tested, but adds weight and bulk. MSR also offers the MiniWorks in a purifying kit that comes with virus-neutralizing Aquatabs.
Grayl GeoPress Purifier
Weight: 1 lb. 2.7 oz. | Average Filter Time (for 24 oz.): 0:26 | Element Lifespan: 250 L
Grayl has made its name on the fast performance of its purifiers that work like French presses. Fill an outer bottle up with dirty water (there’s a helpful line indicating the max amount), then push the inner bottle, which has an electro-absorptive filter at the bottom, into the muck. In less than 30 seconds, the GeoPress produced 24 ounces of water (for a full liter, the average was 1 minute, 46 seconds) so clear we would have thought it came from the tap if we hadn’t treated it ourselves. It became the standard for clarity that no other models were able to match. We’ve also used Grayl’s Ultralight Purifier and recommend shelling out the extra 20 bucks for the GeoPress, which holds eight more ounces of liquid and has a much better lid. The slightly tacky pads on either side of the carry handle kept our palms comfortable under strain, and the narrow-mouth screw-top cap was pleasant to drink from and easy to open when we needed to let air escape while purifying. Not everything was as smooth to operate. We struggled to separate the inner press from the other bottle, despite the grips designed to help with this. (People with large hands might have an easier time.) And between the large cartridge and all the plastic, the GeoPress is one of the heaviest on our list.
—BEST FOR BASE CAMP—
Platypus GravityWorks 4.0L
Weight: 12.9 oz. | Average Filter Time: 1:10 | Element Lifespan: 1,500 L
If you won’t need to restock your water supply in the middle of your day or are traveling with a buddy, choose this high-output gravity filter. It recorded one of the fastest times in our testing, and the treated water was distinctly clearer than the source. What’s more, the most taxing part of using it was lugging the water-loaded dirty reservoir from a creek or stream a few feet onto the bank where we connected it to the clean side. Then, we released the hose clamp, and physics did the rest. It was most convenient to use when there was a tree branch within reach to hang the dirty side from, but holding that side up or propping it on top of our pack also did the trick. If the four-liter size isn’t right for you, the GravityWorks system also comes in two- and six-liter models. And so you don’t have to carry a third reservoir, Platypus makes a compatible drinking tube that converts the clean one into a usable hydration bladder.
Sawyer Squeeze Water Filtration System
Weight: 6.6 oz. | Average Filter Time: 1:37 | Element Lifespan: 378,541 L
The Sawyer Squeeze is practically as versatile as it is popular. This kit includes all the accessories you need to use it as a bottle, straw, in-line or gravity system, or in its classic squeeze mode. For that, fill one of the two 32-ounce mylar pouches with dirty water, attach the filter, and squeeze the bag so water flows into your clean container. It’s straightforward, but if you’re feeling rusty, the directions are printed right on the pouches. Because of their narrow openings, it was difficult to completely fill the bag in shallow streams, like the one where we did our timed test. We had to refill the pouch twice to reach one liter of clean water, which significantly slowed the process, but in better conditions, it’s never taken more than two minutes. Our sample is still pretty new, so we haven’t encountered the durability issues that some customers and other gear reviewers report. The pouches can burst at the seam after too much pressure, and the O-ring seal on the input side of the filter has been known to leak. The kit includes replacements for each, and you can buy more online, if needed. Still, the Squeeze’s small price tag, lightness, and range of filtering options make it the best bargain buy.
—BEST VALUE PURIFIER—
Survivor Filter Pro Portable Water Filter Pump
Weight: 13.7 oz. | Average Treatment Time: 1:57 | Element Lifespan: 100,000 L
Most purifying gadgets run over $100, but the Survivor Filter Pro bucks that trend. It’s also a compact pump, which saved room in our pack for other gear. The tradeoff is slower speed. Twice during our timed test, the force of the pumping caused the output hose to wiggle out of our water bottle. We had to stop and reposition the tubing before continuing. Survivor Filter adds a clip to help avoid this, but the plastic loop attached to it wasn’t tight enough to be foolproof. Jamming the tube way down into your vessel and using the clip is your best bet. The weight on the pre-filter, which sits at the end of the intake hose to block large particles, isn’t as heavy as those on other pumps, so it had a tendency to float and head down stream in slow moving water. Performance hindrances aside, the purifier does what you need it to do, and the filtration elements are long-lasting (though the carbon element needs to be replaced about every 2,000 liters of water treated). We have noticed some nicks in the plastic housing, but with a little care, the Pro should withstand years of adventures.
Weight: 5.0 oz. | Average Treatment Time: 4:02 | Element Lifespan: 1,000 L
This year, MSR brings its in-line filter, which it developed for the military back in the early 2000s, to the masses. Lightweight and inexpensive, the Thru-Link is also dead simple: Clip it into your reservoir’s drinking tube and access to clean water is just a sip away. It’s slightly more complicated if you don’t have a reservoir with a two-part drinking hose (like Platypus’ Big Zip EVO). Then, you’ll need to cut your reservoir’s drinking hose and install the included connection adapters, which fit together when you don’t need the filter. Our first drink took a little more suction than normal, but once the Thru-Link was primed, we hardly noticed it was there. It can also work—slowly—as a gravity filter, which is the mode we used when determining its average treatment time. Still, that didn’t bother us much given that it’s ideal use is for on-the-move hydration. If you regularly skip reading directions, this is the filter for you.
—BEST FOR EMERGENCIES—
Weight: 2.8 oz. | Average Treatment Time: n/a | Element Lifespan: 4,000 L
Like the Thru-Link, the LifeStraw provided taste-free water almost instantly. Its short stature made it a little uncomfortable to drink with unless we first collected water into a bottle. It’s also not designed for treating water to drink later. But it boasts a long lifespan and the easiest cleaning process of any on this list. All we had to do was blow through the mouthpiece to clear out liquid and other gunk inside the filter. Very lightweight and affordable to boot, it’s a nice backup option to keep on hand.
Katadyn Steripen Ultra
Weight: 5.7 oz. | Average Treatment Time: 1:30 | Element Lifespan: 8,000 activations
The Steripen Ultra uses concentrated UV light to sterilize water. With the touch of a button, the small device treats a half-liter in 48 seconds or a full liter in a minute and half. The OLED screen has a countdown clock, battery life indicator, and tells you when the water is ready or when something’s gone wrong. As for regular maintenance, you only have to worry about the occasional recharge. (A cable and carrying case with a Velcro strap come with the kit.) Katadyn reports the USB-rechargeable device can treat 50 liters on one charge and that the lamp is safe to use up to 8,000 times. A big downside of the Ultra (and other UV units) is that it doesn’t separate out particulate matter, and cloudy water can hamper its performance. So Katadyn makes a pre-filter that screws onto wide-mouth water bottles to catch sediment. It’s an extra expense on top of an already pricey gadget, but the filter shouldn’t need replacing until it forms a hole. For a lower cost alternative, pour water through a piece of cheesecloth or simply let it rest and scoop the cleaner water into a different bottle for treating.
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