Tactical Gear

5 Best Ultralight Backpacking Water Filters


You can’t have enough clean drinking water when out on a weeks-long backpacking trip. The thing is, you can’t carry gallons of H2O without compromising the weight of your pack, either!

There’s always a stream or spring to quench your thirst along the way…but outdoorsmen know better than to trust a water source just because they look clean. Even the clearest water sources could be riddled with bacteria, parasites, and other nasties.

So, how do you get a cool drink without risking an upset stomach?

The solution is pretty simple: take an ultralight backpacking water filter with you.

These lightweight water filters are designed to be taken on the road and filter out contaminants like particulates, bacteria, and parasites through hollow fiber technology. Unlike other methods, these filters take as little as five minutes to do the job and don’t affect the taste of the water, either.

Using a backpacking water filter is like hitting two birds with one stone: you get to reduce the weight of your pack while ensuring a supply of clean, drinking water during your backpacking trip.

Now, the question is…which filter best suits your needs?

Table Of Contents

    Choosing The Right Backpacking Water Filter

    Backpacking water filters come in all shapes and sizes. These filters may be similar in function, but their differences can also make or break their performance.

    Choosing the right one that fits your needs is crucial for a smooth and enjoyable time outdoors, so we took the liberty of reviewing the best water filters out on the market.

    How Do Water Filters Work?

    Backpacking water filters may have their differences, but they all have one thing in common: they use hollow fiber membrane technology.

    It works like this:

    Think of hollow fiber membranes as tiny tubes, like straws. Along the tubes’ walls are thousands, even millions of tiny pores. These pores are so tiny that anything bigger than 0.2 or 0.1 microns can’t go through. To give you an idea of just how wide a micron is, an average human hair strand is around 10-200 microns wide.

    So yes, these pores are ridiculously small, and they are very effective against harmful microorganisms since most bacteria and protozoa are bigger than 0.2 microns.

    The filtration then happens when dirty water passes through the hollow fiber membranes either through gravity, sipping or squeezing.

    What Types of Microorganisms Do These Filters Protect You From?

    Most filters are effective against the following microorganisms:


    According to the CDC, 1.2 million salmonella cases are recorded each year, with around 450 cases ending in death. Salmonella is a type of bacteria that live in animal and human intestines and is eventually excreted in feces. You can get salmonella infection through improper food or water handling.

    Common signs and symptoms of salmonella infection include diarrhea, fever, and abdominal cramps within 8-72 hours of contact. When untreated, this could eventually lead to severe dehydration and shock.


    Escherichia coli (or E.Coli, as it is commonly known) is also a type of bacteria found in the gut. While most E.Coli strains are harmless, other types can cause severe gastrointestinal upset, pneumonia and even urinary infections.

    E.Coli can be transmitted through food that is not thoroughly cooked, unpasteurized milk and, of course, contaminated water, especially those found in lakes, ponds or sources that can come in contact with animal manure.

    Signs and symptoms include bloody diarrhea, vomiting, and even acute kidney failure in some cases.


    Giardia is a kind of protozoan parasite. It has a tough shell that protects it from chlorine disinfection. Giardia is most often transmitted through contaminated water and is one of the leading causes of gastrointestinal disease in the US. Giardia infection is common during the summer. Hikers, campers, and backpackers are especially at risk.

    Signs and symptoms of Giardia infection include loose, greasy stools, flatulence, and abdominal cramps.


    Cryptosporidium or crypto is a microscopic parasite. Like Giardia, it also has a tough shell that is impervious to chlorine and is one of the leading causes of waterborne diseases in the States. Infected people can come down with watery diarrhea within 2-10 days of contact.

    Why Can’t Filters Get Rid Of Viruses?

    If you’ve noticed, all filters in this list can’t get rid of viruses.

    This is because viruses are usually smaller than bacteria and parasites. You will need a device with an even smaller pore size, usually at 0.01 microns. Unfortunately, outfitting gravity and straw filters with 0.01 microns is somewhat counterproductive and difficult since water flow would be very slow.

    That being said, only pump-assisted devices are made with pores this size. They’re actually no longer considered as filters but are now classified as purifiers.

    If you’ve noticed, we left out the pump filters because while they’re very effective, pumps also weigh significantly more (none of these ultralight filters weigh more than 12 ounces, while the lightest pump filter can easily weigh 20 ounces or more). Plus, pumping takes a lot more effort.

    The good news is, waterborne viral diseases are not an issue in the States, where water standards are high. If you’re traveling to developing countries, however, you might want to look into pump filters or other modes of water purification.


    Platypus Gravityworks

    Quick specs:

    • Type: Gravity Filter

    • Weight: 11.5 oz

    • Lifespan: 1,500 liters

    • Best for: Hiking, backpacking, camping

    • Filter size: 0.2 microns

    • Effective against: waterborne bacteria and protozoan parasites; not effective against viruses


    • Gravity-fed; no hand pumping required
    • Able to filter up to 1.5 liters/minute
    • Lightweight compared to pump filters
    • Has a reservoir for clean water
    • Quick backflushing that can be done on the field
    • Convenient storage
    • Has adapters for various water storage devices


    • Does not remove viruses, iron, sulfur, other chemicals or simple compounds
    • Ziplock top used to secure dirty water reservoir can be cumbersome
    • Difficulty gathering water from shallow source
    • Has a lot of small accessories
    • Ultrafiltration hollow fiber membrane could be susceptible to freezing

    Platypus Gravityworks reservoirs

    Great For:

    Big groups, campers, hikers

    Filter Lifespan:

    1,500 liters

    What People Are Saying:

    189 reviews on Amazon with 91% 4-5 star ratings

    For a lot of backpackers, gravity water filter systems were a revelation. Imagine, no more tired hands from all the pumping! The Platypus Gravityworks is one of two awesome gravity filters in this review and suffice it to say that it and the MSR Autoflow did not disappoint.

    What we love about the Platypus is that it’s got two reservoirs, one for dirty water and another for the clean, filtered water. That means you can store and carry clean water back to camp with you. Large volumes of it, too, as the Platy is available in 2-liter and 4-liter systems (we used the 2-liter system for this review). It’s great for big groups or if you’re going on a long-haul trek with few rest stops in between. Both reservoirs are made of plastic— tough but flexible— and can easily be cleaned and then rolled for storage.

    assembling the Platypus Gravityworks

    What we didn’t love about it is that it has a lot of little parts. Literally a small issue in the grand scheme of things, considering that the Platypus is an excellent water filter, but when you’re out in the backcountry assembling a filter with so many tiny accessories, it can be a chore. Be that as it may, these little parts include the various adapters that allow you to use your Platy filter in a lot of ways, so you just have to be organized on the trail to avoid contaminating your adapters.

    The dirty water bag is secured by a ziplock top. It can be quite difficult to close or even open the bag once you’ve filled it to capacity or after multiple uses. The bag itself, however, has sturdy straps so you can use those to hold the bag up or hang it on an elevated place, like a tree branch.

    Its manufacturers proudly state that the Platypus can filter 1.5 liters per minute. It had been raining further upstream when we tested the product, so the water source was, at best, the color of fresh latte. All the better to put the products to the test.

    Holding the Platypus Gravityworks' dirty reservoir

    The Platy worked at a decent speed but it wasn’t what we expected. In our experience, we got about 1.75 liters in 2 minutes— that’s barely a liter at half the time. On the plus side though, it consistently delivered the same volume after repeated use and didn’t slow down.

    The system can be cleaned right on the field through backflushing, which was a breeze. Other product reviews state that they have a bit of difficulty with the backflushing, but as per our experience, it was quick and easy. It took about 3-5 minutes of continuous backflushing before the water turned clear again.

    The Platypus Gravityworks can be used to filter 1,500 liters of water in its lifetime.

    All in all, the Platy did great. Its clean water reservoir was convenient and it made backflushing easier.

    Sawyer Mini

    Quick specs:

    • Type: hollow fiber filter

    • Weight: 2 oz

    • Lifespan: 100,000 gallons

    • Lifespan: 100,000 gallons

    • Best for: Individuals and groups

    • Filter size: 0.2 microns

    • Effective against: waterborne bacteria and protozoan parasites; not effective against viruses


    • Very versatile; it can be used in many different ways
    • All raw materials are BPA free
    • Solid technology with great reputation for dependability
    • Can filter 100,000 gallons
    • Best price-performance ratio


    • Can only filter small quantities of water at a time
    • Does not remove viruses, iron, sulfur, other chemicals or simple compounds
    • Ultrafiltration hollow fiber membrane could be susceptible to freezing

    The Sawyer Mini

    Good For:

    Hikers, Backpackers, Preppers….everyone in the whole wide world, as long as you’re not a very large group

    Filter Lifespan:

    100,000 gallons

    What People Are Saying:

    4,082 Amazon reviews with 94% 4-5 star ratings

    Last but definitely not the least, we have the Sawyer Mini, which blew all other personal filters out of the water (forgive the pun). You can really tell that Sawyer really put their back into this water filter.  It’s so small that it can fit in the palm of your hand, but here’s the kicker:

    It can filter up to 100,000 gallons with its backflushing capability.

    Let that sink in.

    For comparison, the Lifestraw, which is slightly heavier than the Mini at 2 ounces, can only filter 1000 liters or 264 gallons.

    There’s a lot of things to love about the Sawyer Mini.

    First, it’s so versatile. It comes with a sturdy pouch that you can attach to the filter, allowing you to take the water wherever you go. The reservoir is also collapsible so you can roll it up when not used.

    You can drink directly from the reservoir with the filter attached, or you can use the system to filter water into other containers. Yes, it can be used to filter several bottles of water, although it’s not as efficient compared to the gravity filters featured in this review.

    drinking water from a water bottle using the Sawyer Mini

    Next, the system comes with a straw so you can also use the filter to directly drink from a water source, like how you would with a Lifestraw. The catch is, you won’t necessarily have to get down and dirty. The Sawyer Mini can be screwed on most plastic water bottles. As long as you can squeeze the bottle, you can definitely drink from it. This is the usual problem with many water filters and we are ever so glad that Sawyer came up with this solution.

    Another advantage is that you can also use the Sawyer inline with your hydration bladder.

    The kit comes with a syringe that you can use to backflush the filter.

    Attaching the Sawyer Mini to a plastic water bottle

    Perhaps the only disadvantage to the Sawyer Mini is that the pouch can’t carry more water. It can only hold 16 ounces at a time so filtering large amounts of water can be pretty exhausting after a while. To be fair, though, the Sawyer Mini was designed as a personal water filter. And there’s definitely a workaround for it, too. Since the Mini can be screwed onto most plastic and soda bottles, you can simply replace the pouch with a bigger reservoir.

    All in all, the Sawyer Mini ended up being the best of the bunch, thanks to its versatility and excellent price-performance ratio. We highly recommend it to anyone who loves the outdoors.

    MSR Autoflow

    Quick specs:

    • Type: gravity filter

    • Weight: 10.9 oz

    • Lifespan: 1,500 liters

    • Best for: hiking, backpacking or camping with large groups

    • Filter size: 0.2 microns

    • Effective against: waterborne bacteria and protozoan parasites; not effective against viruses


    • Gravity fed – no hand pumping required
    • Can filter large quantities of water (2L and 4L)
    • Filters fast at 1.75 liters/min
    • Has adapters for various water storage devices
    • Reservoir includes a buckle for additional security from the possibility of popping open


    • Doesn’t come with a clean water reservoir
    • Getting water from a shallow source can be difficult
    • Does not remove viruses, iron, sulfur, other chemicals or simple compounds
    • Ultrafiltration hollow fiber membrane could be susceptible to freezing

    The MSR Autoflow gravity filter at use

    Great for:

    Big groups, campers, hikers

    Filter Lifespan:

    1,500 liters

    What People Are Saying:

    Only 2 reviews on Amazon but both for 5 stars

    The second gravity filter in this review is the MSR Autoflow and it met expectations with flying colors. Unlike the Platypus, the MSR doesn’t come with a clean water reservoir, which could be a pro or con however you look at it.

    This means that you’ll have to provide a clean water container of your own, which could be a water bottle or a hydration bladder. The kit does have adapters for both, so it’s not a very big problem. While having a clean water reservoir like the Platy does have its benefits, you’ll also have less small parts to deal with, which makes set-up faster and easier. Either way, it doesn’t discount the fact that MSR’s performance was great.

    What we love about it is that it filters really fast.

    It’s advertised to filter an impressive 1.75 liters per minute. In our experience, we got about 1.5 liters a minute, which wasn’t far off the mark. It yielded the same volume after multiple uses.

    Testing out the MSR's buckle

    The MSR’s dirty water reservoir not only looks sturdy; it feels like it too. The reservoir’s texture has a bit of bite and won’t likely slip from your hands when you’re gathering water from a fast-running source. We loved the fact that you can secure it using a buckle instead of a ziplock because a buckle is less prone to pop open.

    Backflushing, however, can be a bit challenging because the MSR doesn’t have its own clean water reservoir. You certainly can’t backflush properly if you’re using a wide-mouthed bottle or a container that’s not compatible with the MSR’s adapters. In our case, we used the Platy’s clean water reservoir together with the MSR’s bottle adapter to gather the filtered water. Thankfully, it was a perfect fit between the two. We had a bit of trouble on the first attempt and had no flow at all. The second try yielded better results. We had a clear flow in about 2 minutes of continuous backflushing.

    All in all, the MSR is the faster filter on this list, but you gotta make sure that you have a compatible clean water reservoir for backflushing.

    Katadyn BeFree

    Quick specs:

    • Type: hollow fiber filter

    • Weight: 3.2 oz

    • Lifespan: 1,000 liters

    • Best for: lightweight backpackers, hikers or runners

    • Filter size: 0.1 microns

    • Effective against: waterborne bacteria and protozoan parasites; not effective against viruses


    • Portable
    • Collapsible
    • Lightweight
    • All raw materials are BPA free
    • Flow rate is very fast compared to Sawyer and others – comes out as fast as you can squeeze it
    • Has a 1000 L filter life


    • Unable to backflush; you can, however, shake water in the bottle to clean the filter
    • Can only carry 1L of water at a time
    • Ultrafiltration hollow fiber membrane could be susceptible to freezing
    • Does not remove viruses, iron, sulfur, other chemicals or simple compounds

    A man sitting down and holding his BeFree water filter

    Great for:

    Hikers, runners, lightweight backpackers

    Filter Lifespan:

    1,000 liters

    What People Are Saying:

    84 Amazon reviews, with 73% 4-5 star ratings

    The Katadyn BeFree water filter is like the lovechild of the Lifestraw and the Platypus. Like the Lifestraw, it’s very portable. The flask is collapsible so it won’t take so much space in your bag. It can even fit in someone’s back pocket so it’s great for lightweight hikers, backpackers, and runners. Like the Platy, you can actually carry water with you. Sure, it’s nowhere near the Platy’s 4-liter max capacity, but anyone knows that a little hydration goes a long way when you’re on the trail.

    The Katadyn BeFree is pretty easy to use. You don’t need a complicated set-up and you can have a drink of water in a jiffy. The filter is attached to the drinking nozzle, so all you have to do is get water, attach the filter and squeeze. Just make sure you don’t contaminate the nozzle’s tip.

    Filter size is at 0.1 microns, so it’s effective against most waterborne bacteria, protozoa, and parasites, but won’t do much against viruses. When the filter has already reached its lifespan, you can simply buy a new one. The reservoir itself has a great texture for grip; although it is quite smaller than most, it doesn’t easily slip from your hands, especially when you’re gathering water from a running source. While the reservoir can only carry 1 liter of water at a time, you can use the filter to easily fill up other containers with clean water.

    A man squeezing the Katadyn BeFree filter

    The disadvantage of the Katadyn comes in when it’s time to clean. You can still clean it on the field— you basically fill the bottle with water and shake it clean, or take the filter out and swirl it around freshwater to clear it up. Obviously, unlike gravity filters, you can’t do any backflushing to ensure the quality of the filter. Washing it horizontally can also damage the filter.

    Another disadvantage is that the filter is not compatible with a lot of water bottles. You need to be careful not to break or puncture the bottle or the filter would be of little to no use unless you buy a new one. Take note that the Katadyn BeFree doesn’t come in cheap— it costs about twice as much as the Sawyer Mini, which we’ll discuss in a bit.

    All in all, the Katadyn BeFree is great for personal use. It just came out on around August 2016, so its technology is still pretty new. That being said, it’s prone to have some growing pains in the R&D department, like issues about quality control and field failures that need to be addressed. It’s pretty great when it works, but it could be a pain in the butt when it suddenly stops working.


    Quick specs:

    • Type: Survival Straw

    • Weight: 2oz

    • Lifespan: 1,000 liters

    • Best for: emergencies, bugout bags

    • Filter size: 0.2 microns

    • Effective against: waterborne bacteria and protozoan parasites; not effective against viruses


    • Lightweight compared to gravity and pump filters
    • Portable
    • No waiting time for purification
    • All raw materials are BPA free


    • Can only filter small volumes at a time
    • Not for large groups
    • Unable to store clean water
    • Unable to fill up external containers for cooking, etc.
    • Sucking thru straw is not so easy compared to just drinking water from bottle
    • Ultrafiltration hollow fiber membrane could be susceptible to freezing
    • Does not remove viruses, iron, sulfur, other chemicals or simple compounds

    The Lifestraw

    Great For:

    Emergency situations, personal survival kits

    Filter Lifespan:

    1,000 liters

    What People Are Saying:

    4,082 Amazon reviews with 94% 4-5 star ratings

    Any self-respecting backpacker or prepper would recognize what a Lifestraw is. This light and slender personal filter was originally designed to give developing countries access to clean drinking water. It was also meant to be used as an emergency filter in disaster-stricken areas. Since it’s so portable and relatively cheap, the Lifestraw quickly gained popularity in the backpacking and prepping communities.

    And boy, is it portable.

    At only 2 ounces, the Lifestraw is exceptionally light and easy to carry around. It takes little space in a bag, making it great for people who are always on the move, like backpackers or hikers. The Lifestraw is also ideal for preppers who want a personal filter in their bug out bag or survival kits. It even comes with a lanyard so you can wear it around your neck. The lanyard itself, however, doesn’t look sturdy enough and if we’re being honest, you’re better off replacing it with a length of 550 paracord.  The 550 is more reliable and is something that you can deploy as cordage when the need arises.

    A man with a lanyard attached to a Lifestraw

    The filtration process is pretty straightforward. Unlike other water purification devices, you don’t have to wait for your water to be filtered via gravity or pump. You simply have to find a source (be it a river, stream or puddle) and drink from said source using the Lifestraw. More often than not, it results in going on your hands and knees to take a sip from a body of water, which can be messy or inconvenient. You’d also need a couple of strong sips to get started, so sipping from a shallow water source is tricky.

    What’s great is that this device is effective against 99.999% of waterborne bacteria, protozoa, parasites and particulates and can effectively filter as much as 1000 liters of water—- enough for one person for a year. Cleaning it is also simple: all you gotta do is puff out of the filter to expel any nasties that might block it.

    And that’s the thing about the Lifestraw.

    The simplicity of its design is also its biggest downside. While it’s understandable that the straw was meant for urgent needs and short-term crises, it doesn’t discount the fact that, well, it’s pretty limited.

    using a Lifestraw to drink water directly from a water source

    First of all, it’s a personal filter: you can’t use it for big groups or if you’re bugging out with the family.

    You’d have to get one Lifestraw each and even then, you still will be unable to store and bring clean water with you. You’d always have to be on the lookout for a water source to drink from, or, as an alternative, lug around unfiltered water in a container with an opening wide enough to accommodate the Lifestraw. You will also be unable to filter water for cooking and other purposes. Using the Lifestraw is pretty okay if you’re staying in one place, but if you’re hiking or camping out? Not so easy.

    All in all, the Lifestraw wins in terms of portability. It’s pretty handy to have in emergencies as a personal filter. But if you’re a big group that would consume and store large amounts of water at a time, you might want to look at the other water filters in this list.

    Final Thoughts

    When it comes to choosing the right backpacking water filter, you have to keep in mind that one size does not fit all. A filter that might be perfect for a solo backpacker might not be the best fit for those hiking in groups. You really have to identify your needs and priorities.

    We ended up picking out the best ultralight water filters for different types of outdoor enthusiasts. If you’re a solo backpacker or cross-country runner, there’s the Katadyn BeFree. Its collapsible squeeze flask can carry up to 1 liter and you can conveniently carry it with you as a personal filter.

    If you want a personal filter that you can use even in emergencies, you can whip out the Lifestraw. It’s light and portable and a must-have for every bug out bag.

    The Sawyer Mini is the most versatile of the bunch: you can use it as a personal or group filter and really is the best bang for your buck out of all the filters in this list.

    If you’re a big group, there are the two gravity filters: Platypus Gravityworks and MSR Autoflow. It was a tight competition between these two. MSR is the faster filter, but the Platy has the advantage of having a clean water reservoir. Whatever floats your boat, you can’t go wrong with these two.

    It’s important to note that one should follow the manufacturer’s directions to ensure that the filters last long and prevent contamination. These filters have their own pros and cons, and we hope that this review would help you in choosing the right filter that fits your needs.

    So, these are our top 5 ultralight backpacking water filters. What’s yours? Let us know in the comments below!





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