We cover everything you need to know about backpacking water filters—why they’re important, how the different filtration methods work, and which models are our personal favorites.
The ability to filter water is critical for most multi-day backpacking trips. Being able to turn any natural water source you come across—like rivers and lakes—into clean and safe drinking water is what makes most extended backcountry trips possible (otherwise you would have to haul all your water with you!).
And while a good water filter system is such an important piece of backpacking gear, finding the right one can be really difficult. I know this could be said about a lot of topics, but I honestly can’t think of anything more nuanced than backpacking water filters.
There are just so many different factors to consider: the actual method of filtration (physical, chemical, or UV), the different designs (gravity, squeeze, pump), and different configurations (in-line or batch). On top of that, there’s a bunch of science-y and tech-heavy terminology to wade through. Some of it relevant, some of it not. You get the point. It’s a lot.
But don’t worry, we are going to break it all down for you!
In this article, we’re going to highlight the reasons why it’s important to use water filtration (and carry a backup) when backpacking, review the main methods of filtration, discuss the pros and cons of different designs, and offer our personal recommendations of filters we have used and loved.
Top recommended backpacking water filters
Best Lightweight Water Filter: Katadyn BeFree
Best High Capacity Gravity Filter: Platypus GravityWorks
Best Purifier for International Hiking and Travel: Grayl
Best Backup Water Purification: Micropur
When do you need a water filter?
You should always use a water filter when backpacking or hiking. Even if the water source looks to be perfectly clear, there is no way of knowing what’s going on upstream, far beyond your sight. Perhaps livestock defecated in the middle of the stream, an animal carcass has been washed into the water, or a recent rainstorm has unearthed a hiker’s poorly dug cathole.
While the overall likelihood of you getting sick might be low, the consequences if you do get sick can be quite severe.
Our take: I have personally suffered from rapid dehydration on a few occasions, once from contaminated water in Mexico City. I went from perfectly normal to writhing on the ground in less than 8 hours. If I had been in the backcountry, unable to walk, burning through my limited food supplies, and without access to a bathroom, I would have been smashing the SOS button on my inReach satellite messenger. It is not worth the risk.
Types of waterborne pathogens
Any water source on the planet can potentially contain hazardous waterborne pathogens. In the backcountry, even pristine-looking water—like a crystal clear alpine stream—can be contaminated by humans, livestock, or local wildlife further upstream.
Pathogens can rapidly multiply inside the human body, so even ingesting a very small amount can quickly lead to issues. Below are the most common waterborne pathogens found in the backcountry.
Protozoa include Cryptosporidium parvum and Giardia lamblia. Protozoa have hard cyst-like outer shells that make them resistant to certain generic chemicals, like chlorine. Thankfully, they are relatively large (as far as pathogens go) which makes them relatively easy to filter out.
Bacteria include Salmonella, Campylobacter, Escherichia coli (E. coli), etc. These are just a few of the many different types of bacteria that can be harmful if ingested. Again, thankfully bacteria are medium-sized, making them relatively easy to filter out.
Viruses include Hepatitis A, rotavirus, and norovirus. Viruses are much smaller than protozoa and bacteria, making them very difficult to filter out. Water filters do not filter viruses—the exception being filter-purifiers. However, viruses typically need to come from a human source (e.x. feces), so the likelihood of water containing a virus in remote backcountry locations in the US is very low.
While the pathogens listed above affect the human body in different ways, the most common symptoms are stomach ache, diarrhea, and vomiting. This combination can lead to extreme dehydration within a matter of hours.
Water filter vs. water purifier
While we often refer to them broadly as “water filters”, there’s a very important difference between water filtration and water purification.
Water filtration systems remove protozoa and bacteria. Most water filters physically “filter” out pathogens using various mechanical methods like a hollow fiber membrane.
Water purification systems remove protozoa, bacteria AND viruses. Water purification can be achieved through advanced physical methods like ion exchange and charcoal filters, advanced hollow fibers, UV light, and chemical means.
So, which one do you need?
In backcountry areas where the likelihood of human contamination is very low, we usually will just use a filter.
In areas where there’s a higher chance of human contamination, such as super popular canyons with only one slow-moving water source, you may want to consider using a purification system. Additionally, if you’re going to be hiking abroad, where safe drinking water can’t even be guaranteed on tap, you definitely want a water purification system.
Types of backpacking water filters
Squeeze filters are made from hollow fiber membranes and are most often paired with a soft bag or flask that you fill with dirty water. Then, you squeeze the water through the filter into a clean bottle or reservoir, your cookpot, or directly into your mouth. These filters tend to be lightweight, inexpensive, and have no mechanical parts to worry about. They do, however, tend to have a decreased flow rate over time which, with certain filters, can be partially addressed by backflushing. Pre-filtering water that is cloudy or contains sediment using a bandana or buff can help prevent the decrease in flow rates.
Gravity filters use, well, gravity to pull water from a “dirty” reservoir bag hung on a tree (or held up high) through a hollow fiber filter and into either a clean reservoir or bottle. These filter systems tend to be a bit heavier than squeeze systems due to the reservoirs, hanging straps, and tubes, but they are a great way to filter a lot of water with minimal effort and are an excellent option for groups or base camping.
Pump-style filters use a hand pump to force water through a hollow or glass fiber filter. A hose, many of which have a pre-filter attached, is dropped into the water source and then you hand pump until you have all the water you need. Unlike the other filtration systems, this one requires you to remain at the water source for the duration of the time it takes you to filter. Pumps are also heavier than other filter systems (the exception being the MSR TrailShot).
UV light purifiers use a UV bulb to destroy the DNA/RNA of bacteria, protozoa, and viruses, making them unable to reproduce and in effect, killing them. It is critical to pre-filter your water using a bandana or buff so there are no particles in the water. If a virus or bacteria is hanging out on the backside of a floatie, the UV light won’t hit it and it will be allowed to reproduce freely. While lightweight, UV purifiers rely on batteries (either replaceable or USB rechargeable), which should be taken into consideration.
Chemical purifiers like Aquamira drops and Micropur tablets contain chlorine dioxide, which, given enough time, destroy bacteria, protozoa, and viruses. Iodine is another chemical treatment available, but it does not kill all protozoa (namely Cryptosporidium). Chemical treatments are usually used as backups, though some opt to use them for their primary treatment method.
What about boiling?
Boiling water is always a purification option, and will kill bacteria, protozoa, and viruses. This may be your best option if you’re camping in freezing conditions as many filters can’t withstand being frozen.
If you’re going to use this method, bring water to a rolling boil for one minute at elevations below 5,000 feet or three minutes for elevations about 5,000 feet (per the EPA). Be sure to pack along extra fuel if this is going to be your primary purification method.
Features & buyer considerations
In addition to different methods of filtration, there are many different water filter design features to consider as well. Some water filters are designed to be ultralight while others prioritize flow rate, some are made to be used in-line with a reservoir system while others are self-contained units.
Ease of use
First and foremost, it’s important to consider ease of use when choosing a water filter for backpacking and hiking. If a filter is difficult to use, you’re likely to filter less and in turn decrease your water consumption, increasing your risk of dehydration. For individuals, quick or no set-up filters like the BeFree and Sawyer Squeeze are likely to be easiest to use. For groups, a larger capacity gravity filter like the Platypus GravityWorks will make quick work of filtering water for the group despite the set-up time.
If you’re trying to get miles under your feet, or get away from your water source ASAP before you get devoured by mosquitoes, the speed at which you can filter water will be an important factor. For squeeze, pump, and gravity filters, look at the “flow rate” to compare the speed of various models.
Weight, of course, is always a concern to backpackers. Luckily, there are lots of lightweight options, though they do usually come with some tradeoff in the durability or convenience departments (if you’ve ever tried to fill a Sawyer Squeeze bag in a slow-moving creek you’ll know what I mean). A filter like the GravityWorks is heavier but comes with perks like a large capacity bladder and easy field maintenance.
Filter lifespan is something to consider, but unless you’re thru-hiking the PCT you aren’t going to hit the lifespan of most filters very quickly. But, you will want to keep in mind that for most filters (the exception being the Sawyer Squeeze) you will need to purchase a replacement filter or replace the system entirely at some point.
Available water sources
What types of water sources will you have available to you on your hike and how frequently will you come across them? Some filters work best with flowing or deeper water sources (like the BeFree, Sawyer Squeeze, and GravityWorks), while others like pump filters will still work well in shallow and still sources.
If you’re going to be using sketchy water sources (we see you, PCT & CDTers) you may want a filter or purifier that does a good job of filtering out organic matter, bad tastes, and chemicals. If you’re going to have to hike miles between sources, you won’t want to choose a system that limits your capacity—or, have extra storage bottles available so you can load up when needed.
Many hollow fiber filters, like Sawyer filters and GravityWorks, will require you to backflush often in order to maintain its flow rate. Pump filters might require you to physically remove the filter and clean it if it begins to clog.
Some filter options require water bottles to collect water before treating, so you’ll want to keep that in mind when purchasing bottles to make sure that they will be compatible with your chosen filter.
Best backpacking water filters
Weight: 2.3 oz (with 1L flask)
Claimed Flow Rate: 2L/min
Filter Life Span: 1,000L
Removes: Bacteria (99.9999%) & protozoa (99.99%)
The Katadyn BeFree is an ultralight water filter that connects to a soft flask. You can squeeze the water through into another water bottle, use the filter cap to drink straight from the flask, or even rig it up as a gravity filter.
It has a super fast flow rate, though you should expect it to decrease over time. Choosing clear water sources will help maintain the flow rate, as will swishing the filter around in clean water from time to time.
One complaint that we’ve read in reviews is that the bottle the BeFree comes with isn’t super durable. If that’s a concern, you can buy the filter cap separately and purchase a more durable 42mm bottle to pair it with, like the Hydrapak Flux. We also found that it took some time for the plasticy taste of the included flask to dissipate.
The BeFree has been our go-to this season for backpacking, hiking, and trail running. You just can’t beat its ease of use and weight!
Weight: 3.5 oz (filter only)
Claimed Flow Rate: 1.7L/min
Filter Life Span: Lifetime
Removes: Bacteria (99.99999%) & protozoa (99.9999%)
The Sawyer Squeeze is another squeeze-style water filter that screws onto a water bottle or a soft pouch that comes with the filter—though after reading multiple reviews of the bags failing, we’re inclined to toss ours and just attach it to our Smartwater bottles.
What sets the Sawyer Squeeze apart is it’s light weight and that it boasts a lifetime warranty on the filter. In theory, you will never have to replace it. From a sustainability standpoint, we love this aspect of the Squeeze.
That said, the flow can decrease over time and requires backflushing using an included syringe, which will add an ounce to the advertised weight. But, it’s worth carrying on longer backpacking trips or trips where you’re likely to encounter less than pristine water sources, as backflushing can restore up to 98.5% of the flow rate.
Type: Squeeze / Inline
Weight: 2 oz (filter only)
Claimed Flow Rate: varies, .5L/min in some field tests
Filter Life Span: 100,000 gallons
Removes: Bacteria (99.99999%) & protozoa (99.9999%)
The Sawyer Mini is lighter weight and smaller than the Squeeze and has the same functionality. Additionally, it can be used as an inline filter so it’s a great option if you use a hydration bladder while backpacking or hiking and want to attach your filter to the hose (assuming you are OK making your bladder a “dirty” bag). We have also seen many hikers simply screw it to the top of a standard plastic water bottle to drink through.
The downside to the Mini is that it has a slower flow rate than the Squeeze, so while it’s a fine flow rate to drink from, it will take you considerably more time to squeeze larger amounts of clean water into extra water bottles or fill up your cookpot to make dinner.
Type: Gravity / Reservoir
Weight: 11.5 oz
Claimed Flow Rate: 1.75L/min
Filter Life Span: 1,500L
Removes: Bacteria (99.9999%) & protozoa (99.9%)
The Platypus GravityWorks is a (you guessed it) gravity filtration system—which means all the hard work is taken care of by gravity while you sit back and wait for your clean water to be ready.
Given its larger capacity and weight, this is a great filter option for groups small and large, but perhaps a little overkill for solo backpackers. Though we’ve moved on to the BeFree for most backpacking trips, Michael and I used the GravityWorks system on our JMT thru-hike. We’ve gotta say it was really nice to only have to walk down to our water source once and be able to grab enough water to take care of dinner, breakfast, and our initial water bottle fill the next day—especially when mosquitoes were abundant.
That said, this system was a bit cumbersome to use while hiking during the day. It has to be assembled and rigged up each time, and we certainly never needed to filter 4L of water at a time any time other than at camp.
At the end of the day, the GravityWorks is a great large-capacity water filter with a fast flow rate, and we still have it in our gear closet for backpacking with groups of three or more.
Weight: 15.9 oz
Claimed Flow Rate: 5L/min
Filter Life Span: 250L
Removes: Bacteria (99.9999%), protozoa (99.9%) & viruses (99.99%)
The Grayl Geopress is a water bottle purifier, meaning it removes viruses in addition to bacteria and protozoa. To use it, you fill the bottle and then press the filter down, which can take a bit of muscle. We recommend setting it on flat ground and using your body weight to help press.
The downsides of this purifier are the weight and the short filter lifespan (though you can buy replacement filters, and Grayl is committed to recycling spent filters if you send them back). You’re also limited to the capacity of the bottle, so it’s best used where there will be frequent opportunities to fill up.
On the other hand, filter-purifiers can be very expensive and Grayl puts a portable water purification system in your hands for a very attractive price. We think it’s a great option for internal travel & hiking where even tap water might be unsafe to drink. We also think it’s a great option for day hikes where you will be relying on heavily impacted water sources.
Type: UV Light
Weight: 3.8 oz (with batteries)
Time to Purify: 1.5min/L
Battery Life: up to 50L
Bulb Lifespan: 8,000L
Eliminates: 99.9% of bacteria, protozoa, viruses
Type: UV Light
Weight: 4.8 oz
Time to Purify: 1.5min/L
Battery Life: up to 50L per charge
Bulb Lifespan: 8,000L
Eliminates: 99.9% of bacteria, protozoa, viruses
The Steripen Adventurer Opti and Ultra models are nearly identical in terms of how they work: a UV lamp is placed in your bottle of water and stirred for 90 seconds as it deactivates the DNA structures of bacteria, protozoa, and viruses. For either model, it’s critical to pre-filter your water using a bandana or buff so there are no particles in the water. If a virus or bacteria is hanging out on the backside of a floatie, the UV light won’t hit it and it will be allowed to reproduce freely.
The difference between the two models is how they are powered: the Adventurer Opti takes two CR123 batteries. It will purify up to 50L from a set before the batteries need to be replaced. The Ultra is rechargeable via USB, and will purify up to 50L on one charge.
For weekend backpackers, the difference is negligible since you’re unlikely to run through the 50L battery life on either. For longer hikes, the Ultra may be the better option since you can charge it off a battery pack or solar panel, and you don’t have to worry about trying to send lithium batteries in your resupplies.
We have used the Opti and the predecessor to the Ultra and would recommend either as a lightweight water purifier for backpacking and hiking trips on high-impact trails where viruses may be present.
Weight: .9 oz for 30 tablets
Time to Purify: 4 hours
Eliminates: Bacteria, protozoa, viruses
Micropur tablets are expensive and impractical to use as your main water treatment method, but they are great to have in your pack as a backup in case your main system fails.
These tablets dissolve in your water, and then it takes 4 hours to completely purify it. They do leave a bit of a chemical aftertaste.
But, at less than an ounce for 30 tablets, it’s a no-brainer for us to throw a handful into our first aid kit just in case.
Primary water filter / secondary water purification
With a function as important as water filtration, we highly recommend that you carry a backup just in case of failure.
A very common setup is to have a primary water filter system (something like the Katadyn BeFree or Platypus GravityWorks) but also carry a chemical water purification option (like the Micropur Tablets).
You will normally only use the filter because it’s quicker, removes cloudiness and sediment, and doesn’t adversely affect the taste of the water. But if that primary filter happens to fail for some reason, you can switch to the backup system.
Those Micropur tablets are super lightweight, so it’s not really a bother to carry them around just in case. But they do take longer, don’t remove cloudiness, and add a somewhat strange taste to the water. Not ideal, but they will work in a pinch.