Everyone exploring the backcountry needs water, but staying hydrated is not as simple as drinking straight from streams and lakes. To protect against protozoa, bacteria, and even viruses, there is a wide range of water filtration and purification systems built specifically for backpacking (many options on this list are great for day hiking, trail running, and travel too). Our top picks for 2021 below include everything from ultralight straw filters and chemical drops to pumps and large-quantity gravity filters.
Table of Contents
- Our Backpacking Water Filter/Purifier Picks
- Backpacking Water Filter/Purifier Comparison Table
- Backpacking Water Filter/Purifier Buying Advice
Type: Gravity filter
Weight: 11.5 oz.
Filter life: 1,500 liters
What we like: Filters and stores a high quantity of water effortlessly and quickly; great for groups.
What we don’t: Bulky; you need a decent water source to fill the bag.
Without a doubt, the Platypus GravityWorks is one of the most convenient water filters on the market, and it’s become a backpacking staple. Instead of pumping, this system requires minimal effort, can filter up to four liters of water at once, and boasts a speedy flow rate of 1.75 liters per minute. Gravity does all the work: simply fill up the 4-liter “dirty” reservoir, hang it from a tree branch or boulder, and in just a few minutes you’ll have four liters of clean water to drink. This filter is great for large groups, but we’ve enjoyed it on smaller outings too when we could quickly retrieve our day’s water and escape back to our camp to fill individual bottles (the clean bag also functions as water storage).
But compared to some of the more minimalist options below, the Platypus GravityWorks is not a small apparatus, with two bags, a filter, and a bundle of tubing. Furthermore, water retrieval can be a pain if you don’t have a reasonably deep or moving water source (similar to any system that relies on a bag to collect water). And at $110, the GravityWorks is on the more expensive end of the water filtration spectrum. But we love the convenience, especially for groups of backpackers or basecamp-type situations, and feel it’s worth the cost and bulk then. Keep in mind that you can also save a little with the GravityWorks Bottle Kit, a 2-liter system that filters water directly into your bottle or reservoir ($90, 9.5 oz.)... Read in-depth review
See the Platypus GravityWorks 4L
Type: Bottle/inline filter
Weight: 3 oz.
Filter life: Lifetime
What we like: Super lightweight, fast flow rate, long-lasting.
What we don’t: More effort than gravity filters.
The Sawyer Squeeze epitomizes ultralight water treatment and has been a mainstay on the thru-hiking scene for years. At just 3 ounces, it provides filtered water as fast as you can, well, squeeze. The system works by filling the included 32-ounce pouches with dirty water, then squeezing them into a clean bottle or reservoir, a pot for cooking, or straight into your mouth. For solo travelers or small groups moving fast and light, it’s a simple option, provided you know the location of river crossings or other water sources (or carry additional bottles along for storage). And with a lifetime warranty, Sawyer doesn’t even make replacement cartridges for this filter.
This streamlined water filtration system does have its downsides. First and foremost, collecting water with the included pouches can be challenging if your source is shallow or not moving quickly. Second, squeezing a liter of water is more effort than letting a gravity filter do the work (Sawyer does include an adapter for converting the Squeeze into a gravity or inline filter). And finally, the flimsy pouches are known to break—most hikers will replace them a Smartwater bottle or more durable Evernew bag. All gripes aside, the Squeeze remains excellent for ultralight adventurers, but we recommend a gravity filter (or chemical treatment) for parties of three or more. And for those who want to go even lighter, Sawyer does offer “Mini” and “Micro” versions, but both have painfully slow flow rates that aren’t worth the 1-ounce (or less) weight savings.
See the Sawyer Squeeze Water Filter
Type: Pump filter/purifier
Weight: 17.3 oz.
Filter life: 10,000 liters
What we like: The most advanced portable water purifier on the market.
What we don’t: At $350, the Guardian is the priciest option on this list.
The MSR Guardian is ten times the price of many popular bottle filters here, but this pump is the real deal. Most importantly, it’s both a water filter and purifier, which means you get the highest level of protection against protozoa, bacteria, and viruses, along with a filter that removes debris. Further, the Guardian uses advanced self-cleaning technology (about 10 percent of water from each pump cycle is used to clean the filter) and is far less likely to break down than cheaper models. The result is ultimate peace of mind when backpacking and traveling in less-developed regions of the world or other high-use areas (viruses are most commonly carried in human waste). In fact, the Guardian is such a reliable and convenient system that it’s also used in the military and as an emergency water purifier after natural disasters.
But for all its strong suits, the MSR Guardian is overkill for many. Aside from cost, it’s noticeably bulkier than most pump filters at just over a pound and packing down roughly to the size of a 1-liter water bottle. Further, while the purifying capabilities are smart for traveling and backpacking in certain regions of the world, they’re not necessary in most wilderness areas in the United States and Canada. Nevertheless, the Guardian truly is the ultimate backpacking purifier and worth the cost for those who need it. And it’s important to note that MSR also makes the Guardian Gravity Purifier ($250), which features the same advanced technology of the Guardian but in a gravity setup... Read in-depth review
See the MSR Guardian Purifier System
Type: Chemical purifier
Weight: 0.9 oz.
Treatment ratio: 1L per tablet
What we like: Simple and light.
What we don’t: More expensive than Aquamira and you’re drinking unfiltered water straight from the source.
Similar to Aquamira drops below, Katadyn Micropur tablets are a simple and effective chemical treatment using chlorine dioxide. For backpackers, there is a strong argument for going this route: the tablets weigh less than 1 ounce for 30, making them by far the lightest water purification option on this list. In addition, each tablet is individually wrapped and therefore can be modified for the specifics of your trip (with Aquamira you have to carry both bottles no matter the length of your trip). In order to use the Katadyn, just add one tablet to a liter of water, wait 15 minutes for protection from viruses and bacteria, 30 minutes for Giardia, and four hours for Cryptosporidium.
The biggest downside of any chemical treatment is that despite the water being clean, it’s still unfiltered (in the Utah desert, for example, that may mean brown water with lots of critters). But in alpine areas with relatively clear mountain water like the Rockies, High Sierra, or Pacific Northwest, chemical treatments are a great ultralight option. And in comparing chemical treatments, it’s worth noting that despite being more difficult to use, Aquamira drops are considerably cheaper. We ran the numbers and you’re paying roughly $0.49 per liter of clean water with Katadyn whereas Aquamira is more like $0.13 per liter. Plus, the Katadyn tablets are difficult to cut in half and don’t work with 500mL bottles (it’s one tab per liter), which is a bummer especially for trail runners with smaller soft flasks.
See the Katadyn Micropur MP1
Type: Bottle filter
Weight: 2.3 oz.
Filter life: 1,000 liters
What we like: Extremely light and great for on-the-go hydration.
What we don’t: Less versatile than the Sawyer Squeeze.
The Katadyn BeFree is our favorite dedicated bottle filter, with an extremely light weight, easy operation, and nice, streamlined build. Instead of squeezing like you do with the Sawyer Squeeze above, the BeFree allows you to drink as you would from any standard water bottle, with the water passing directly through the filter on its way to your mouth. The design excels on long trail runs when water is readily available: the compact filter sits inside the HydraPak bottle (unlike the protruding Sawyer Squeeze), its wide mouth makes it easy to refill, and the whole set-up is a feather light 2.3 ounces. Plus, the bottle has a nice soft touch (albeit cold when full of stream water), and when empty, the BeFree system can fit in the palm of your hand.
All that said, the Katadyn BeFree isn’t without its drawbacks. First, it has a relatively short lifespan compared to a filter like the Squeeze (1,000 liters vs. the Sawyer's lifetime warranty). Second, the BeFree filter only is compatible with bottles with a 42-millimeter mouth, so it’s not as versatile as the Sawyer which fits a variety of standard 28-millimeter water bottles. Third, in use we noticed a faint plastic taste when using the bottle, which also has been the case with other HydraPak products (the bottle is BPA-free, but nobody wants their water to taste like plastic). Finally, the Katadyn is $10 more plus the potential cost of a new filter ($25), and lacks the versatility of the Sawyer’s gravity adapter. But as a dedicated bottle filter, the BeFree wins out for its ease of use and streamlined design.
See the Katadyn BeFree Collapsible Bottle 1L
Type: Inline/gravity filter
Weight: 2.5 oz.
Filter life: 1,000 liters
What we like: For those who hike with a water reservoir, the convenience is unmatched.
What we don’t: Bladder compatibility can be an issue.
There was a lot of press surrounding the release of MSR’s Thru-Link Inline Water Filter, and for good reason. Rather than manually filtering into a bottle or a separate reservoir, the Thru-Link Inline attaches directly to the hose of your bladder and filters as you hike. Simply dip your reservoir into a water source and start drinking. When you get to camp, the MSR also can be used as a traditional gravity system for pump-free filtration. Add at a scant 2.5-ounce weight, affordable $40 price tag, and impressive flow rate of 1.5 liters per minute, it’s a lightweight and convenient way of hydrating on the go.
Although the Thru-Link Inline Water Filter is compatible with any water reservoir system, there are some limitations. First, it’s important to point out that while most newer bladders support the connection system on the MSR (any bladder with Quick-Connect fittings will work), others require you to modify by cutting the reservoir tube and utilizing the two included fittings. Permanently altering your water bladder isn’t ideal, but neither is purchasing a separate reservoir. Compatibility issues aside, for those who like to drink from a bladder, the convenience of the MSR is hard to match.
See the MSR Thru-Link Inline Water Filter
Type: Pump filter
Weight: 11 oz.
Filter life: 750 liters
What we like: A versatile and reliable filter that can make clean water from puddles.
What we don’t: Relatively short filter life and pricey to replace.
Pumping water has its downsides, but we’ve found that the Katadyn Hiker is one of the most reliable filter options across a wide range of backpacking scenarios. Simply put, you break out your Hiker, place the hose end in the water, screw the other end onto your Nalgene (or hold it over top if you have a different type of bottle or reservoir), and pump. You get roughly one liter of clean water per minute if you’re pumping at a good clip, and we’ve found that the Hiker Microfilter works faster and is easier to use than the MSR MiniWorks below. Unlike the MSR Guardian, however, the Hiker is a filter but not a purifier, so you don’t get virus protection.
In terms of construction, the Katadyn Hiker is well-built for a pump, but these systems are not infallible. The device is made of ABS plastic and has a number of hoses and small parts, and we’ve had pieces snap off of other pumps in the past (not with the Katadyn yet, but it certainly can happen). Another downside is the rather pricey replacement filter: after approximately 750 liters, you’ll need to spend $50 for a new one (the MSR MiniWorks recommends a replacement filter after 2,000 liters and that costs $40). But we still prefer the Katadyn, which despite the shorter filter life, has faster and smoother pumping action.
See the Katadyn Hiker Microfilter
Type: Chemical purifier
Weight: 3 oz. (total for both bottles)
Treatment ratio: 30 gallons per 1 oz. set
What we like: Light, cheap, effective, and won’t break.
What we don’t: The mixing process is annoying, and the drops leave a faint chemical taste.
There are a number of chemical water treatment options for backpackers, and each has its own set of pros and cons. At just 3 ounces and $15, Aquamira is a liquid chlorine dioxide solution that effectively kills protozoa, bacteria, and viruses. To purify your water, mix 7 drops each of Part A and Part B in the included cap, let it sit for five minutes, and add the mixture to 1 liter of water. Then wait 15 minutes before drinking for protection from Giardia, bacteria, and viruses, or four hours to kill Cryptosporidium (that takes a lot of advanced planning). Without a doubt, this system is inexpensive, lightweight, and won’t malfunction like some of the more complicated filters and purifiers on this list.
Our biggest issue with Aquamira drops is the mixing process. It slows you down on the trail, takes some concentration in terms of measuring out the drops, and can bleach your clothing if you’re not careful. Compared to the Katadyn Micropur above, Aquamira is much more of a process, but the good news is that it's cheaper and can treat a variety of different volumes (the Katadyn is a strict 1 tablet per liter and is difficult to halve), which makes it great for group use. Finally, keep in mind that with any chemical purification system, you get no filtration and therefore will be drinking all of the particles that make their way into your bottle. This generally is fine for clear mountain runoff but is not optimal for those acquiring water from smaller or more stagnant sources.
See the Aquamira Water Treatment
Type: Bottle/inline filter
Weight: 3.2 oz.
Filter life: 2,000 liters
What we like: Versatility of an inline filter in an all-in-one bottle design.
What we don’t: Short filter lifespan and slow flow rate.
If the Sawyer Squeeze and Katadyn BeFree filters above have caught your eye, it might be worth taking a look at the LifeStraw Flex. In many ways the Flex is a combination of the two: like the BeFree, it comes with its own soft flask and filters water as you drink, which is a great set-up for shorter pursuits like trail running and day hiking. But—similar to the Sawyer Squeeze—the Flex has a two-way design that can pull double duty as a straw filter, inline filter (akin to the MSR Thru-Link above), and gravity filter. In the end, the LifeStraw Flex offers the all-in-one convenience of the BeFree alongside the versatility of the Sawyer Squeeze (without the need to buy any extra parts).
But for all of its design strengths, the LifeStraw Flex doesn’t quite measure up in the details. For one, while the 2,000-liter lifespan is double that of the BeFree, it pales in comparison to the Squeeze’s lifetime warranty. Second, the soft flask isn’t as durable as the HydraPak included with the purchase of the Katadyn, and it’s only available in a small 0.7-liter size (although unlike the BeFree you can pair the Flex with most disposable water bottles). And finally, in practice the Flex is noticeably slower than the competition, and the flow rate is difficult to revive through simple maintenance. It is worth noting that for $20 more, you can get the Flex filter and a 3.7-liter bag for a convenient gravity system.
See the LifeStraw Flex
Type: Gravity/pump filter
Weight: 16 oz.
Filter life: 1,500 liters
What we like: Effortlessness of a gravity system combined with the convenience of a hand pump.
What we don’t: Heavier than the Platypus GravityWorks and slower to filter.
You won't find a more versatile water filtration system than the MSR Trail Base. Combining a gravity filter system with their popular TrailShot hand pump, MSR created a unique combination that works well whether you're at basecamp or on the trail. Like the Platypus GravityWorks, our top pick, the Trail Base comes with two reservoirs—a dirty and a clean—which hang and cycle water to the clean reservoir by way of gravity. Unlike the Platypus, the filter on the Trail Base easily disconnects and doubles as a fully functional hand pump (the TrailShot) for water on the go. Furthermore, the clean reservoir works great for carrying water, eliminating the need for bulky water bottles. This multi-function design makes the Trail Base an attractive option for basecampers and backpackers who want easy access to water during the day.
However, all this versatility comes with a cost. First, the Trail Base is a bit cumbersome as a gravity filter, cycling only 1 liter of water per minute (the GravityWorks filters 1.75 liters per minute). Second, the system weighs a hefty 16 ounces, significantly more than the 11.5-ounce Platypus (which notably is a 4-liter system). Keep in mind that for the weight, you do get a gravity filter, squeeze hand pump, and drinking reservoir in one, which is quite impressive. Sawyer offers similar versatility with their 8.8-ounce Gravity System that incorporates the Squeeze, but it's a less convenient design with just one reservoir. And for a simpler gravity setup, check out MSR's 10-liter AutoFlow XL.
See the MSR Trail Base Gravity Filter System 2L
Type: UV purifier
Weight: 2.6 oz.
Lamp life: 8,000 liters
What we like: Lightweight and inexpensive purification.
What we don’t: Relies on USB charge.
For well over a decade, SteriPen has held a unique place in the water purification market. Instead of the various gravity filters, pumps, and chemical drops on this list, the UltraLight uses UV rays to destroy bacteria, protozoa, and viruses—a full purification process at less than 3 ounces total for the unit. It takes about 90 seconds to purify 1 liter: you simply place the SteriPen in your water and swirl until the light turns green. Keep in mind that the SteriPen purifies but does not filter your water, and therefore you’ll want a good source.
We love the concept of the SteriPen but have mixed feelings after extended use. The lack of filtration certainly is a downside and means that unless you don’t mind drinking silt or other particles, you’re limited to moving water sources of a decent depth. Second, the SteriPen uses a USB-rechargeable lithium-ion battery, and if that runs out and you don’t have a portable charger, you’re stuck in the wilderness with no purification. Finally, when using the SteriPen, it’s hard to feel totally confident that it worked—rational or not. Did I submerge the device too little or too much? Is the process really complete? But we’ve never been sick after using a SteriPen and a green light indicates when treatment is finished, so those concerns haven’t yet been realized.
See the SteriPen UltraLight UV Water Purifier
Type: Pump filter
Weight: 16 oz.
Filter life: 2,000 liters
What we like: One of the few pump designs with a ceramic filter.
What we don’t: Heavier and slower than the Katadyn Hiker.
Despite all of the recent innovations and newer releases like the TrailShot, the MSR MiniWorks remains one of the most popular pumps on the market. Compared to the Katadyn Hiker above, both are similar in price (the Katadyn is $20 cheaper), have the same filter pore size (.2 microns), and protect against the same things including Giardia and Cryptosporidium. The Katadyn is lighter at 11 ounces, but the MSR has a significantly longer filter life at 2,000 liters (the MSR is carbon/ceramic while the Katadyn is carbon). And both allow you to filter water without the inconveniences of straws or droplets.
We have the MSR MiniWorks ranked here because of our personal experience with it. We found the pump to be slow from the outset (it has a listed flow rate of 1 liter per minute, but we didn’t experience that). Further, our version became almost unworkable midway through a Utah backpacking trip. The water was rather murky, but that’s no excuse for pump failure just a few days out of the box. User reviews generally are positive and we are looking forward to getting another MiniWorks out for more testing, but regardless, we’ll take the lower weight and initial cost of the Katadyn.
See the MSR MiniWorks EX Microfilter
Type: Bottle filter (gravity and inline adapters available)
Weight: 2 oz.
Filter life: 100,000 gallons
What we like: Feathery light.
What we don’t: We’ll stick with the better-performing and longer-lasting Sawyer Squeeze.
One ounce lighter and $20 cheaper than the Sawyer Squeeze above, the Sawyer Mini is one of the lightest and most compact water filters on the market. Like the Squeeze, the Mini attaches to its included bag or other compatible water bottle to squeeze filtered water into your mouth or drinking vessel. Unlike the Squeeze, however, the Mini doubles as a straw, giving it the versatility of a bottle, straw, or gravity/inline filter (the latter option requires purchasing extra components).
It shouldn’t come as a surprise that this smaller and less expensive version is slower to filter and more prone to clogging. In fact, we brought the Mini along as our personal filter on a 4-day trek in Patagonia (with clear water sources), and it required so much suction that we resorted to using our group’s gravity filter instead. Additionally, it’s light on accessories: the 16-ounce pouch isn’t ideal for filling up standard water bottles, and you have to pay extra to convert the Mini into an inline filter. All told, we don’t recommend the Mini for anything other than emergency use, especially given that the Squeeze is a fully functional alternative for just 1 ounce and 20 bucks more.
See the Sawyer Mini Filter
Type: Pump filter
Weight: 5 oz.
Filter life: 2,000 liters
What we like: The smallest and lightest pump filter available.
What we don’t: Clunky to use and filtering performance slows over time.
At a weight that’s less than half of Katadyn's Hiker above and size small enough to fit in your pocket, the TrailShot is a nice on-the-go filtration system for trail running and day hiking. This minimalist, one-handed pump allows you to filter water without laying on the ground (such as with a basic LifeStraw) or getting cold hands by filling up and squeezing bottles (as you might with the Sawyer Squeeze or Katadyn BeFree). Additionally, it works well in shallow pools or streams, which is a weak point of many squeeze and gravity systems. And with the ability to filter about 1 liter per minute, the TrailShot keeps up with the competition in terms of speed (at least on paper).
But despite weighing only 5 ounces, the MSR TrailShot is among the heaviest of the ultralight filters on this list. Additionally, the integrated hand pump is somewhat clunky to use and it’s easy to get fatigued while filtering multiple bottles or a large reservoir. It’s also slow compared to more serious pumps, particularly in dirty water, and backflushing doesn’t help much to speed things up. In the end, the TrailShot falls short of ultralight filters and pumps alike, giving us pause to recommend it as a primary option for full-on backpacking trips (especially with groups). But if you’re looking for an ultralight pump filter for day trips and light-duty use, the TrailShot is a good bet.
See the MSR TrailShot Water Filter
Type: Bottle filter/purifier
Weight: 10.9 oz.
Filter life: 150 liters
What we like: An innovative and simple purification system.
What we don’t: Not a versatile design (one bottle per person).
The Grayl Ultralight Water Purifier is designed with travel and light adventuring in mind. We like the concept: similar to the LifeStraw Universal below, the Grayl replaces the myriad awkward devices on this list—requiring some level of squeezing, pumping, batteries, hoses, or even chemicals—with a simple and sleek 16-ounce bottle. Plus, it’s available in a variety of colors, notably offers purification on top of filtration, and has a nifty French-press-style plunger to get the job done. And Grayl also makes the 24-ounce GeoPress, which features the same technology in a larger capacity bottle (and with a nozzle for drinking).
Though eye-catching and certainly useful for a wide range of scenarios (think traveling in lesser-developed countries or hydrating in camp), the Grayl has limitations. Purifying just .5 liters at a time, it’s an inefficient system for anything but on-the-go drinking when water sources are consistently available. Additionally, the purifier cartridge has a lifespan of only 150 liters, which pales in comparison even to the LifeStraw Universal's 4,000 liters. But no other bottle filter beats the Grayl for traveling abroad, and it’s a great replacement for buying water in disposable plastic bottles. For backpacking, the practicality is limited.
See the Grayl Ultralight Water Purifier Bottle
Type: Chemical purifier
Weight: 3.8 oz.
Filter life: 60,000L+
What we like: Can filter 60,000 liters with little upkeep.
What we don’t: Less convenient than other chemical purification options.
Now for something a little different: Potable Aqua’s Pure Electrolytic Water Purifier. Unlike most chemical purifiers that use chlorine dioxide or iodine, the Pure combines salt water and an electric charge to remove contaminants from water. This technology is more common in military and municipal applications than the outdoor world, although we’ve even seen it before with MSR’s now-discontinued Miox. In general, it’s a simple, lightweight set up that can purify 1-20 liters at a time, boasts a lifespan of 60,000 liters, and charges (slowly) using the attached solar panel.
The Pure Electrolytic comes with the same downsides of nearly all chemical treatment options. It adds an unfortunate taste, takes a half hour to do its job (or four hours if you’re worried about Cryptosporidium), and does not remove floaties like a filter would. And as with every form of water treatment that uses power, we recommend bringing a backup option into the field in case the Pure malfunctions. All told, the Pure is intriguing, but it isn’t our favorite chemical purification option—we’ll stick with the more reliable chlorine dioxide for most applications.
See the Potable Aqua Pure Electrolytic Purifier
Type: Straw filter
Weight: 3.6 oz. (without bottle)
Filter life: 4,000 liters
What we like: Makes water filtration as easy as drinking from your favorite bottle.
What we don’t: Heavier and bulkier than the Katadyn BeFree
For those wanting a dedicated water bottle filter, the LifeStraw Universal has a lot of appeal. Like the Katadyn BeFree above, it makes water treatment as simple as taking a sip, but it goes the next mile with a universal adaptor (hence the name) that can attach to your water bottle of choice (including narrow and wide mouth models from Hydroflask, Klean Kanteen, CambelBak, Nalgene, and more). Additionally, LifeStraw Universal boasts four times the filter life of the Katadyn and doesn’t require any squeezing (read: no cold hands). All in all, it’s an ideal and long-lasting set-up for casual day hiking, when weight and bulk aren’t always a top consideration.
But for all of its adaptability, the LifeStraw Universal isn’t incredibly versatile. You get a bottle of filtered water, and that’s about it. And because it’s a straw filter, you can’t even use it to squeeze water into an empty bottle or a pot for cooking (like you might with the BeFree or Sawyer Squeeze). Further, 3.6 ounces is the weight of the filter alone, which is more than double the more backcountry-focused Flex above. And take note that the Universal’s straw is bulky, so it reduces the total amount of water storage. But for short adventures and compatibility with your favorite water bottle, the LifeStraw Universal is one of the most convenient and user-friendly options here.
See the LifeStraw Universal Bottle Adapter
Type: Chemical purifier
Weight: 3 oz.
Treatment ratio: 1/2 liter per tablet
What we like: Lightweight and cheap.
What we don’t: Tastes funky and takes 30 minutes to activate.
Potable Aqua tabs are a classic and a method that we’ve used as a filter backup for years. The system couldn’t be simpler: put two iodine tablets in a liter of water, wait 30 minutes, and drink. Most importantly, they kill bacteria, protozoa, and viruses, thereby purifying water for drinking. Similar to the Aquamira drops, Katadyn tablets, and SteriPen above, keep in mind that you will be drinking unfiltered water, so Portable Aqua is best used with relatively clean mountain water.
The big downside of Potable Aqua is taste. Neutralizer tablets are available and do a decent job of masking the chemical flavor, and many people add a drink mix to make a tastier concoction. If you’re wondering about the differences between iodine (Potable Aqua) and chlorine dioxide (the Katadyn and Aquamira above), the former is not effective in killing Cryptosporidium, while the latter is categorized by the CDC as having low to moderate effectiveness. Further, the Katadyn and Aquamira don't have as many issues with taste, which is why they land higher spots on our list.
See the Potable Aqua Tablets
|Platypus GravityWorks 4L||$110||Gravity filter||11.5 oz.||1.75 L/min||1,500 liters||2L, 4L|
|Sawyer Squeeze||$37||Bottle/inline filter||3 oz.||1.7 L/min||Lifetime||32 oz.|
|MSR Guardian||$350||Pump filter/purifier||17.3 oz.||2.5 L/min||10,000 liters||Unlimited|
|Katadyn Micropur MP1||$14||Chemical purifier||0.9 oz.||1 L/30 min||1 liter/tab||Various|
|Katadyn BeFree Bottle 1L||$45||Bottle filter||2.3 oz.||2 L/min||1,000 liters||20 oz, 1L, 3L|
|MSR Thru-Link Inline||$40||Inline/gravity filter||2.5 oz.||1.5L/min||1,000 liters||Unlimited|
|Katadyn Hiker||$70||Pump filter||11 oz.||1 L/min||750 liters||Unlimited|
|Aquamira Water Treatment||$15||Chemical purifier||3 oz.||1 L/20 min||30 gallons/1 oz.||Various|
|LifeStraw Flex||$35||Bottle/inline filter||3.2 oz.||.5L/min||2,000 liters||0.7L|
|MSR Trail Base Gravity 2L||$140||Gravity/pump filter||16 oz.||1 L/min||1,500 liters||2L, 4L|
|SteriPen UltraLight UV||$90||UV purifier||2.6 oz.||1 L/90 sec||8,000 liters||Various|
|MSR MiniWorks EX||$100||Pump filter||16 oz.||1 L/min||2,000 liters||Unlimited|
|Sawyer Mini Filter||$22||Bottle filter||2 oz.||Unavailable||100,000 gallons||16 oz.|
|MSR TrailShot||$50||Pump filter||5 oz.||1 L/min||2,000 liters||Unlimited|
|Grayl Ultralight Bottle||$70||Bottle filter/purifier||10.9 oz.||.5 L/15 sec||150 liters||16 oz.|
|Potable Aqua Pure||$100||Chemical purifier||3.8 oz.||20 L/30 min||60,000 liters||Various|
|LifeStraw Universal||$35||Straw filter||3.6 oz.||Unavailable||4,000 liters||Various|
|Potable Aqua Tablets||$8||Chemical purifier||3 oz.||1 L/30 min||1/2 liter/tab||Various|
- Water Filtration vs. Purification
- Types of Water Filters and Purifiers
- Weight and Bulk
- Pore Size
- Flow Rate
- Filter Life
- Filter Maintenance/Replacement
- Compatibility with Bottles and Reservoirs
- Water Taste: Chemicals and Carbon
- Emergency Backups
The words “filter” and “purifier” often are used interchangeably, but knowing the differences between the two is a key step in choosing the best water treatment for your needs. The most important distinction comes in the level of protection each method provides. Water filters use microscopic pores to strain out protozoa (such as Giardia) and bacteria (E. Coli and Salmonella, for example). Water purifiers also remove protozoa and bacteria, but they eliminate viruses as well (like Hepatitis A and the Norovirus). Viruses are rarely found in natural sources, which is why most backcountry goers find filters to be fully sufficient. However, if you’re traveling in less-developed regions of the world or just want to be extra cautious (especially in high-traffic areas), a purifier is a great option to have.
Second, by definition, a filter routes water through an actual sieve, which physically removes debris such as dirt, algae, leaves, and tiny critters. By contrast, most purifiers use chemicals or ultraviolet light to treat water straight from the source (i.e. unfiltered water). This is important to keep in mind if you’re drawing from unclear water sources such as a silty river, murky pond, or muddy desert pool. We’ll usually opt for a filter in these scenarios, but if you’re using a purifier it’s a good idea to pre-filter your water (more on this below). Finally, some premium treatment options both filter and purify water, such as the MSR Guardian.
Gravity systems—which use an inline filter—are best for groups, basecamping, or anytime you want to filter large quantities of water with minimal hands-on effort. Simply fill the dirty water bag, hook up the filter to the port or hose, and let gravity do the work. Some gravity systems have a separate “clean” reservoir to collect the water, while others dispense it straight into your vessel (or mouth) via a hose with an on/off valve. Gravity filters aren’t for everyone, however: they’re bulkier and heavier than most alternatives, and you’ll need a fairly good water supply to fill up your reservoir (pumps are better for shallow sources). Finally, gravity filters aren’t our first choice for on-the-go water treatment, as setting up the system can take some time (and you’ll need somewhere to hang it).
Although they’re most commonly used in gravity setups, inline filters also can be paired with a hydration reservoir (purchased separately) to provide on-the-go filtration for solo travelers. Instead of gravity doing the work, suction brings the water from the “dirty” bag, through the filter, and into the hydration hose to the mouth. Used in this way, an inline filter will only add about 3 ounces to your kit (assuming you’re already bringing a reservoir) and is one of the easiest and most efficient ways for individuals to stay hydrated. MSR makes their Thru-Link Inline for this very application, and models like the Sawyer Squeeze quickly convert into an inline filter with included adapters.
Pump filters are a great option for small groups (1-4 people), and especially when you need to pull water from shallow pools. Using simple mechanics (and some elbow grease), a pump siphons water from the source, through a hose and filter, and out another hose into a clean receptacle. But while they have long been a popular option for backcountry filtration, pump filters recently have been outpaced by other styles. They’re among the heaviest systems, take more time and effort than most methods, and cleaning the cartridges isn’t as easy as a simple backflush (as with straw and inline filters). That said, for those who enjoy the process of camp chores and don’t mind a little gear maintenance, we certainly understand the appeal.
Bottle filters—also known as squeeze filters—attach to the spout of a soft-sided bottle or pouch and filter water as you drink. Their lightweight and easy-to-use design makes them a great option for weight-conscious trips and solo backpackers, day hikers, trail runners, cyclists, and more. We love these filters for their versatility—in addition to drinking from the bottle or pouch, you can also squeeze water into a separate receptacle for storage. Further, many bottle filters (like the Sawyer Squeeze or LifeStraw Flex) also can perform as inline or gravity filters (with the help of adaptors), or used as straws to suction water directly from the source. Keep in mind that bottle filters are often slower at filtering than a high-performing pump design and require quite a bit more effort than a gravity model. And with particularly cold water, your hands can get pretty chilly, too.
Used by day hikers, trail runners, and mountain bikers who prefer not to carry water as they move, a straw filter allows you to drink directly from the source, as though sipping through a straw (some setups also include a bottle, like the LifeStraw Universal). Straw filters have their place for simple applications and day trips, but are not a very versatile setup as they offer no way to produce or store clean water for cooking or drinking later. Further, many bottle and inline filters also can be used as a straw (such as the Sawyer Squeeze Mini), and are by far the more well-rounded choice. In general, we don’t recommend simple straw filters for high-performance backcountry use, but we include the LifeStraw Universal on our list as a nice recreational option.
Available in both liquid and tablet forms, chemical purifiers use iodine or chlorine dioxide to remove protozoa, bacteria, and viruses from water. UV purifiers like the SteriPen use ultraviolet rays to achieve the same effect. The upsides to both methods are clear: they’re relatively lightweight, don’t require the arduous task of pumping or squeezing, and you get protection against viruses, too (filters only remove bacteria and protozoa). But keep in mind that both chemical and UV purifiers forgo filtering, making them good options only when you have access to clear water sources like glacial streams. In addition, chemical purifiers can add an undesirable taste to your water, and UV purifiers require batteries and electronics, which aren’t great to rely on in the backcountry. That said, these purifiers offer a nice alternative to bulkier filters, and we especially like chemical options like Aquamira and Potable Aqua for large groups, weight-conscious outings, or as a backup to a filter.
Water filters and purifiers range in weight and bulk, from super lightweight tablets that are just a fraction of an ounce, to the 1-pound 1-ounce MSR Guardian. Most of today’s most popular options for individuals settle in the 2 to 5-ounce range. As with all backpacking gear, you’ll want to go as light as possible without sacrificing too much in the way of functionality. In general, chemical purifiers are the most minimalist option (and great for groups), with squeeze filters like the 2-ounce Sawyer Squeeze Mini not too far behind (although they’re slightly larger in size). Pumps and gravity systems are the heaviest and bulkiest, and include multiple components like storage bags and hoses. Finally, keep in mind that when calculating the weight of your setup, that you’ll also want to factor in your water storage (bottle, reservoir, etc.).
Pore size refers to the size of the tiny openings in the filter, and is measured in terms of microns. The smaller the pore, the more particles the filter can block. According to the CDC guide on water treatment, a pore size of 1 micron (or less) is needed to filter out protozoa, while you’ll need a pore size as small as 0.3 micron to filter out bacteria. Viruses, on the other hand, can be as small as 0.02 micron. Most backpacking filters on this list have a pore size of 0.1 or 0.2 micron, which is why they sift out protozoa and bacteria, but not viruses. Because they are so small, the best way to combat viruses is through chemical or ultraviolet purification. Alternatively, the MSR Guardian pump purifier uses 0.02-mircon hollow fibers to filter viruses.
The flow rate indicates the speed at which a filter treats water, and is most often measured in terms of liters per minute. In general, gravity filters have the fastest flow rates: the Platypus GravityWorks filters 1.75 liters per minute, which means it only takes a few minutes to fill a 4-liter bladder with clean water. Leading pump filters are listed at about 1 liter per minute, although that seems fairly optimistic to us (the exception is the pricey MSR Guardian, which is speedy at 2.5 L/min.). Finally, squeeze and straw filters can only move as fast as you can drink, and some will require more suction than others (the Sawyer Squeeze Mini takes a ridiculous amount of effort). Keep in mind that the flow rates listed by the manufacturers are going to be realized in optimal circumstances and are likely to be slower in the field, and most filters come with recommendations for backflushing or light maintenance to keep things moving properly (more on this below).
Because chemical and ultraviolet purifiers do not filter water, they don’t have a flow rate. However, they do have a wait time that must lapse before water is safe to drink, usually between 15 and 30 minutes (and sometimes a full 4 hours for Cryptosporidium) for chemical purifiers, and 90 seconds per liter for a SteriPen. The good news about chemical purifiers is that you can sit back and let them do their work, rather than pumping or squeezing as in the case of some filters. All told, flow rate will be an important consideration for groups and time-conscious endeavors, but less of an issue for more casual hikers and backpackers.
A key product specification that we reference in this article is filter life, or how quickly your filter will need to be replaced. The primary consideration here is cost: you have the initial purchase price of the item, but after a certain number of liters of water have been filtered, you’ll need to buy a replacement cartridge. For example, two of our favorite pump filters are the Katadyn Hiker and MSR MiniWorks. The purchase price of the Katadyn is $20 less than the MSR, but it has a shorter filter life of 750 liters vs. 2,000 liters, which is a big difference. Given that the Katadyn replacement filter costs $50 vs. $40 for the MSR, this brings the cost of the system up over a period of years. On the extreme ends of the spectrum, the Grayl Ultralight purifying bottle has a cartridge life of only 150 liters, while the Sawyer Squeeze has a lifetime warranty, and they don’t even make replacement cartridges for it.
As with any manufacturer-provided spec, the listed filter life is optimistic and probably should be thought of as a maximum. Furthermore, many of these filters and purifiers are made with a great deal of plastic and it’s fairly likely that you’ll break another component of the device before the filter expires. Finally, keep in mind that the 750 liters referenced above for the Katadyn is actually a lot for most casual backpackers that get out a few times a year. If your filter lasts that long and you’re ready for a new cartridge, then you’ve gotten a lot of use and clean water out of it, making it a solid investment.
Given that their task is to remove contaminants from water, it should come as no surprise that many water filters need to be cleaned of this buildup. Most gravity and straw filters are maintained by backflushing clean water or air through the filter. With a product like the LifeStraw Universal, this is as easy as blowing out after each drink. Others require a separate piece of equipment, including the syringe that comes with the Sawyer Squeeze. In general, it’s important to read about and practice maintaining your filter at home before taking it out into the field.
Cleaning pump filters is a slightly more intensive process, as you'll need to unscrew the apparatus and either remove the filter or extend a brush down the interior. Instructional videos are available online for almost every product on our list, and you should expect basic maintenance to be part of owning and using a water filter. If you’re not keen on keeping up your equipment, you can always opt for more carefree models like the SteriPen or chemical treatments like Aquamira or Potable Aqua.
As we touched on above, if you’re not using a dedicated filter to separate out sediment and other particulates, finding a clean and moving water source is the best way to ensure your water tastes good. But should you find yourself with no other option, we’ve found a bandana (or other piece of clothing) to be the most effective pre-filtering method for straining out leaves, sand, and other bits before purification. Another option is to scoop the dirty water into a Ziploc bag, let the sediment settle, and transfer the clear water from the top into a bottle for treatment. With especially dirty water sources, pre-filtering can be a great idea even if you’re using a filter to treat your water, as it will mitigate potential clogging.
Almost all water treatment systems have some way of connecting to either a water bottle or hydration reservoir, if not both. This often takes the form of a simple hose or cap that fits onto commonly sized water bottle openings. The MSR Thru-Link Inline Water Filter, for example, attaches directly to your water reservoir hose, and pump filters like the Katadyn Hiker and the MSR MiniWorks have adapters that fit the mouth of a standard Nalgene bottle. Sawyer has played into the fast-and-light community of hikers who use disposable plastic water bottles on the trail, making their Squeeze and Mini versions able to screw into the mouth of a standard plastic water bottle (great for weight savings, less great for the environment). All in all, be mindful of the compatibility for a water filter or purifier to make sure it works with your drinking vessels.
Many water filters and purifiers are able to remove bacteria, protozoa, and sometimes even viruses, but they won’t necessarily change the taste of the water. This isn’t a huge issue when you’re drinking straight from cold mountain streams, but it definitely can be as the quality of your water source deteriorates. If you’re using chemicals to purify your water or drinking from questionable sources—perhaps water with floating leaves or plants growing underneath the surface—taste can come into play in a big way. Remember, this doesn’t mean your water isn’t safe to drink—you’ve filtered or purified it—but you can always add an electrolyte-enhanced drink mix like Nuun Electrolyte tablets to make it more palatable (or in the case of Potable Aqua, use the accompanying neutralizing tablets).
Another way to combat foul-tasting water is to use a carbon filter. Used in the popular Brita kitchen filters, carbon removes chlorine, organic compounds, and other bad odor and taste-inducing materials. Not all portable backcountry filters use carbon, but many on our list do including the MSR MiniWorks and Grayl Ultralight Purifier. Additionally, some models offer carbon filters as add-ons: the Platypus GravityWorks, for example, sells a carbon element separately that can be added to the existing filter, and the LifeStraw Steel edition uses carbon instead of a hollow-fiber membrane. It’s important to note that carbon becomes ineffective before the filter (after approximately six months or 200 liters), so if this is a feature you want to maintain, choose a filter that allows you to purchase the carbon element separately from the complete cartridge.
Last but not least, we should mention that just about every water filter and purifier can malfunction, which may leave you without clean water in the backcountry. In this scenario, you can boil your drinking water provided you have a backpacking stove and extra fuel, but this a time and labor-intensive method. For this reason, we think it’s a good idea to carry a lightweight chemical treatment or basic LifeStraw as an emergency backup. The LifeStraw weighs only 2 ounces and costs $20, and Aquamira drops are just $15 for enough solution to treat 30 gallons of water (and a mere 3 extra ounces in your backpack). Getting sick in the backcountry can be a serious medical concern, so we think having a backup is a smart way to go.
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