Outdoor

The Best Backpacking Water Filters of 2021

We tested the best backpacking water filters and purifiers for your next trip into the great outdoors.

You don’t need much to have a successful backpacking trip. Yes, you’ll need some gear (like a tent,sleeping bag, and a pack), but most of all, you’ll need a way to get clean and safe water while on the trail.

While we explain more in-depth about how water filters work and how to choose below, here are a few things that will help you through this guide. There are many different methods of filtering (or treating) water. The most common methods are through a cartridge or tube, with either activated carbon, UV light, or chemicals.

Filters also come in different styles: straw-style, pump filters, gravity filters, and UV or tablet treatments. They all make water safe to drink but differ slightly in size, durability, and price.

We’ve spoken to thru-hikers, put many of these to the test, and read hundreds of customer reviews to find out which water filters on the market are truly the best.

Scroll through to see all of our recommended buys or jump to the category you’re looking for:

The Best Backpacking Water Filters of 2021

Best Overall: Sawyer Squeeze

This water filter system is the gold standard for many thru-hikers and backpackers across the globe. The Sawyer Squeeze ($37) filters down to 0.1 microns, making it effective against bacteria and protozoa (slightly better than other filters).

It has a great flow rate and comes with a kit to attach to a hydration bladder as well. Thanks to the combination of price and weight, it earns the distinction as the best backpacking water filter.

What customers said: The Sawyer Squeeze has over 1,000 five-star ratings. Top feedback from customers includes the ultralight trail weight, the ease of use (specifically the reusable roll-up squeeze pouch), and the durability over time.

Many customers love that there are no annoying tubes — you just screw the filter onto the squeeze bag or a bottle, and drink.

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Runner-Up: Katadyn Hiker Microfilter

katadyn hiker microfilter

We chose the Katadyn Hiker ($70) because of its great price and performance in the long run. Several users found it can last for 2 to 6 years before having to replace the filter.

The Katadyn Hiker filters down to 0.2 microns for bacteria, protozoa, microplastics, and chemicals.

The only con? You’ll have to pump it, although the flow rate is good enough even for those who like to keep a quick pace on the trail.

What customers said: Hundreds of users have commented on how well this filter works and how long it lasts. We’ve also found it to work great in subpar conditions (think freezing temps and murky waters).

A few reviewers did note, however, the bulkiness is a downside, and some prefer the quality of the newer model, the Katadyn Hiker Pro ($85). Regardless of which model you choose, the Hiker filter performs great and the price is right.

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Best Budget: LifeStraw

Lifestraw - backpacking water filter

LifeStraw ($20) is one of the most consistently high-rated water filters of all time. The simple straw-style filter uses a hollow-fiber membrane that filters out bacteria, protozoa, and microplastics down to 0.2 microns (the standard for water filters). It’s also the lightest on the market at 2 ounces and costs only $20.

That said, it’s only good for drinking water directly from the source and doesn’t work for filtering larger quantities into bottles, so it definitely has its limitations. For long-distance backpacking, you’ll probably need a secondary water filtration method. But it’s a great budget pick and solid option for emergency kits, backpacking, hiking, bugout bags, or international travel.

What customers said: The LifeStraw works great, whether you’re going on a day hike or month-long backcountry excursion. Reviewers especially liked how easy it is to pack and carry, and many customers raved about the clear taste on output.

Other pros: We love this filter for daily adventures and as a backup filter method on longer trips. It also lasts for up to 1,000 L, which is plenty for almost any outdoor adventurer.

Cons: You’ll have to remember to empty the fiber chamber to prevent clogging before storing it away.

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Best Gravity Filter: Katadyn BeFree Gravity 3L

Katadyn BeFree 3L Filter Review

Gravity filters use the always-there force of gravity to pull water through the filter. For that reason, they’re extremely user-friendly. Just fill it with dirty water, hang it, and come back in a few minutes to find filtered water waiting in another container.

They work great for larger groups or when you want to filter a lot of water all at once. They’re also quite light given their speed and ease of use.

The Katadyn BeFree Gravity filter ($70) is the lightest gravity filter on this list at just 6.8 ounces. The Katadyn BeFree filters 3 L at a time and comes with a quick-connect output hose to easily fill multiple bottles, pots, or bladders.

It also doesn’t require common filter maintenance like backflushing. Similar to the Sawyer Squeeze, the flow rate is great, and because the bag rolls down, it’s fairly packable.

It came in as a runner-up behind the Sawyer Squeeze largely because it’s more expensive. But for those who don’t mind spending a little more, this is one of our favorite filters that has proven itself over many backpacking and hunting trips in the Rocky Mountains and beyond.

For more, check out our full review of the Katadyn BeFree Gravity Filter.

What customers said: The Katadyn BeFree system can filter smaller particles down to 0.1 microns. The majority of reviewers love that it’s both easy to use and clean.

Cons: You’ll need a place to hang the filter (so if you’re traveling to beaches or deserts, this might not be the best option).

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Best Tablets: Katadyn Micropur

katadyn micro pur water purifier tablets

If you really don’t want to sacrifice weight to a filter, chemical treatment is a great option. Katadyn’s Micropur M1 tablets ($14) have been a top choice over the years, thanks to their purifying powers and easy-to-use instructions.

Pros: The tablets destroy bacteria, protozoa, and viruses. They are lightweight, fairly budget-friendly, and easy to stash in a pack, pocket, or a first-aid kit.

The only con? You’ll have to wait 4 hours to let the full treatment take effect. (Because of this, we recommend treating your water ahead of time or in larger batches.) These tablets are also a popular backup option.

What customers said: Some claim there is a slight aftertaste, although we like these much better than other chemical treatments. Also, many users agree learning the wait times is important. The tablets destroy viruses and bacteria in 15 minutes, but it takes 4 hours to kill the pesky cryptosporidium parasite.

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Best Water Filter Bottles

Lots of us who use water filters for backpacking or hiking also use them for other types of travel — traveling through airports, locally or abroad. (Bonus: A few of the options below are great for both!)

Here are our top choices for travel water filters, whether your adventures take you overlanding, RVing, on day trips, or on international adventures.

Best Overall: GRAYL GEOPRESS Bottle

GRAYL GEOPRESS Bottle 

The GRAYL GEOPRESS ($65 on sale) uses electroadsorption and activated carbon to purify water. Simply fill, press down, and drink. It is that fast. (Yes, the convenience, fast filter time, and quality of this filter make it worth the $90.)

This is truly the best if you’re drinking from really sketchy, off-grid water sources or want a filter for backpacking that isn’t a bladder and hose system. The GRAYL protects against heavy metals, chemicals, and viruses in addition to common protozoa and bacteria.

We’ve tested and love this filter for international travel, when you may want to filter all tap water before drinking. In this case, it works wonderfully as a constant companion to keep you hydrated anywhere.

We’ve also used it backpacking and thru-hiking on the Appalachian Trail. For one of two people, it is an awesome purification method.

What customers said: Users like its really fast flow rate of 5 L per minute (under 30 seconds to get clean water). The No. 1 complaint is that it’s bulky (though to our editor’s point, not any bulkier than a Nalgene). Also, the replacement cartridges are expensive and need to be replaced every 250 L.

Although it didn’t win our top slot overall, it’s still an awesome choice for backpacking, thru-hiking, and general travel.

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LifeStraw Bottle

lifestraw bottle

This is your best bet for a budget option. The LifeStraw bottle ($40) uses the same type of hollow-fiber filter as the original LifeStraw but is seamlessly incorporated into a BPA-free plastic bottle. The 22-ounce bottle filters down to 0.2 microns and is a good alternative option to the straw if you won’t be near water sources as frequently.

What customers said: Similar to the original LifeStraw, customers love that this bottle is easy to use. It’s even easier than just the straw, as the bottle provides a way to carry and store water when you aren’t near a source. Users also love the price point.

Other pros: It’s reliable and also works for day-to-day use.

Cons: Some customers have noticed the bottle is prone to leaking, and there is no cover or dust protector for the nozzle on the flip cap. Some customers also wish the carabiner was sturdier for clipping to packs when the bottle is full.

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CrazyCap Bottle

crazycap bottle

The CrazyCap bottle($65-70) took home an Innovation award at the Outdoor Retailer trade show. Initial reviewers like the bottle’s design and the great-tasting water on output.

The 17-ounce purifier bottle is well-suited for those who travel often and want clean water but don’t want to pack filters or treatment tablets in their luggage. We also love that unlike plastic, this stainless steel bottle is insulated and keeps water colder for longer.

What customers said: The UVC light not only protects against viruses and bacteria, but it also sterilizes the bottle (referred to as self-cleaning) and can be used to sterilize other surfaces. Its rechargeable nature is awesome.

During testing (we used it once each day), we found the cap to last over a week — making it 8 days until it needed a recharge.

Cons: It’s not cheap. And our bottle has suffered a few dents and dings. But if you’re looking for an option that doesn’t involve filters or maintenance (aside from charging), this is a nice choice.

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RapidPure Bottle ($60)

rapidpure purifier bottle

While RapidPure is a newer brand, its bottle made our list due to its construction and convenience. The RapidPure Bottle ($60) is a purifier, meaning it protects against viruses, protozoa, and bacteria, making it suitable for travel virtually anywhere.

The bottle uses replaceable cartridges with both activated carbon and electroadsorption technology to filter out particles 100 times smaller than the standard 0.2 microns.

What customers said: It protects against everything, has a great flow rate, and customers like that it’s easy to use. But the extra $17 for each replacement cartridge makes it a pricier choice. And we found the plastic cap and shape a bit bulky.

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Best of the Rest

Platypus Gravity 4L

platy

This gravity water filter has won a spot on our list for the second year in a row. Why? The Platypus is good for when you need water for other than drinking (straw filters are great, but not for filtering several liters of water at a time).

The Platypus Gravity system is simple to use and makes filtering water at base camp a cinch.

What customers said: Although this gravity filter is a different style, most customers found the disconnecting shutoff valves and flow system easy to learn — and reliable to boot.

Other pros: Bags are clearly labeled “dirty” and “clean,” so there’s no confusion, and the overall performance is great.

Cons: The filter won’t work in freezing conditions. It also tends to clog with silty water, and some reviewers wished the seals on the reservoir bags were better.

Why this didn’t win: The system can clog, so this filter requires pretty good cleaning and maintenance.

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MSR Guardian Gravity Purifier

msr guardian gravity purifierPhoto credit: Tim Newcomb

With an easy-to-fill 10L reservoir and a 1 L per 2 minutes flow rate MSR claims is 2.5 times faster than the competition, the new Guardian Gravity Purifier ($250) takes technology designed for the military and brings it to groups of backcountry explorers.

The purifier meets NSF P248 testing standards, removing bacteria, protozoa, pathogens, and viruses through the 0.02-micron hollow fiber media with an activated carbon component to pull out chemicals, tastes, and odors.

The setup is simple, even if you do need ample space to get the dirty reservoir at least 6 feet above the clean water receptacle (fairly common for gravity water filters). The speedy flow rate and bottle adapter fitting a range of sizes allow filling of separate water bottles or a larger container with the entire 10 L.

This new purifier might be the best one yet for larger groups. With no backflushing required and a mesh carrying case, teardown comes quick. Read our full review on the MSR Guardian Gravity Purifier.

  • Filter type: Hollow fiber, carbon
  • Weight: 1 lb. 3 oz.

Why this didn’t win: If you’re going where there are no trees for hanging, this could be tricky.

Our only con? The price.

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MSR MiniWorks EX Water Filter

MSR MiniWorks EX Water Filter

MSR makes a few pump filters, but this one is our favorite. The MSR MiniWorks EX ($100) protects against bacteria, protozoa, heavy chemicals, and particulates. One of our favorite features of this filter is the fact it’s compatible with both dromedary bags and Nalgene bottles, so you can easily attach and pump into your drinking vessel.

The filter is ceramic, meaning you clean it over time instead of replacing it (although you may need to replace the tubing). Some users also noted an issue with pressure building up in the filter chamber, causing the flow rate to slow. If you don’t mind pumping, this is still a good filter option.

Why this didn’t win: The MSR MiniWorks is the heaviest filter out of the ones we considered, and you’ll have to clean it often.

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LifeStraw Flex Gravity Filter

LifeStraw Flex Gravity Filter

This gravity filter won a spot on this list for its price and lighter weight — just 6.9 ounces. The LifeStraw Flex Gravity ($55) filters down to 0.2 microns and protects against bacteria, protozoa, and microplastics (not viruses).

It’s also versatile. You can use it as a personal straw, as a gravity filter for groups, or screwed into a standard plastic bottle or bladder. It’s great for solo or group multisport adventures.

Why didn’t this win: The flow rate is slower than advertised, and some users had issues with the seal on the bag. And while the hollow-fiber part of the filter is good up to 2,000 L, the carbon filter portion only lasts 100 L (so you’ll need to buy replacements).

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MSR Guardian

msr-guardian-purifier

The Guardian ($350) filters out nearly everything (including viruses), has an excellent flow rate, and even self-backflushes during use. But for most people, it’s downright overkill.

However, if you’re setting up for a serious adventure that requires filtering a lot of very sketchy water, you may want to consider forking over the cash.

The Guardian can filter a hefty 2.3 L per minute and physically removes viruses, bacteria, protozoa, and particulates, including hepatitis A, E. coli, giardia, cryptosporidium, and more. Just be ready to lug a large item that weighs in at over a pound.

For more, check out our full review of the MSR Guardian.

Why this didn’t win: The MSR Guardian is probably one of the best filters on the market. So why didn’t it top the list? Well, in two words, price and weight. It costs a pretty penny at $350 and weighs considerably more than other filters.

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SteriPEN Adventurer

SteriPEN Adventurer

UV filters are popular for lots of reasons. They don’t require pumping or filtering. And the wait time to kill bacteria and viruses is fairly short (between 60 and 90 seconds).

The SteriPEN ($100) made this list for its low trail weight, ease of use, and long lifetime. (The SteriPEN lasts for up to 8,000 treatments.)

Pros: It takes up almost no space in your pack and kills viruses, protozoa, and bacteria.

Why this didn’t win: It’s expensive and runs on batteries, which you’ll need to remember to pack for the trail.

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Buyer’s Guide: How to Choose a Water Filter

Water filters and water purifiers work in similar ways, but it’s helpful to know the difference when choosing.

Filters vs. Purifiers

Filters protect against protozoa or parasites (such as cryptosporidium and giardia) as well as bacteria (like E. coli or salmonella), microplastics, dirt, and debris. Bacteria is the main concern when you’re drinking out of unsafe water sources in the backcountry or remote areas.

Purifiers go an extra step by protecting against and filtering out viruses. This is more of a concern when you’re traveling internationally or to rural places where clean water may not be accessible.

Filter Time and Flow Rate

Our picks for best water filters vary widely in terms of how quickly they can filter water, ranging from 30 seconds to 30 minutes to 4 hours (chemical treatments). Types of filters and methods of purifying will play a part, as well as flow rate.

Flow rate is a unit that measures how quickly a certain amount of water can be filtered. Flow rates for gravity, pump, or squeeze filters listed here vary anywhere from 1-3 L per minute. If you are encountering a slow flow rate with your filter, it may require priming or backflushing.

Similar to needing to prime a stove, some water filters require priming before initial use. Check the instructions (it varies by filter) on how to do this. Backflushing is a process where you need to clean water out of the fIlter system after use. This mainly applies to filters with pumps, tubes, or tubing, and it ensures the inside of the filter stays dry and clean.

Another consideration here is location: if you are going to be traveling through a desert landscape, there may be few to none trees (a necessity to hang some gravity filters properly). In that example, a different style of filter would be best.

And if you are going to be traveling with a companion or group, the personal LifeStraw filter obviously won’t be the best option (although we love it as a backup!).

Packed Size

This is an important point for ultralight and lightweight backpackers. You’ll want to choose a filter that works best for you and how much water you’ll need, but one that can also fit in your pack.

Filters like the Sawyer Squeeze and Katadyn BeFree are popular because the actual filter unit is so small, and the weight is close to nothing. The Sawyer Squeeze weighs just a couple of ounces, while the Katadyn weighs 6.8 ounces (but remember, it can filter up to 3 L of water at a time).

Filter systems that have water reservoirs and tubing also roll and pack down fairly small. My personal preference on group trips is a gravity filter system, whereas on solo trips — though it weighs slightly more — my preference is a water bottle filter/purifier, given that I always carry a 1L bottle anyway.

Durability and Longevity

The lifespan of a filter greatly depends on its filter method (cartridge, hollow membrane, chemical, or UV light). Backpacking water filters can last anywhere from 250-4,000 L.

Ones that use a cartridge tend to last anywhere from 200-500L before you need to replace the cartridge. On the other hand, with other filters that last longer, you may need to replace the entire unit at the end of its life. The LifeStraw is an example of this — it can filter around 4,000 L, and then it will stop working and need to be replaced.

For UV methods like the CrazyCap filter bottle and SteriPENs, they’ll last forever, as long as you charge or continue to replace the batteries (barring any damage, of course).

Price

Finally, there’s price. We recommend making a list of your top two or three choices and then weighing the pros and cons. Any filter will be an investment.

Pro tip: Check back on this list often to see if any have gone on sale!

Woman Using LifeStraw Personal Water Filter in Stream

FAQ

What Is the Best Way to Purify Water When Backpacking?

The best way to clean your water when backpacking is to use and find the cleanest water source possible. You’ll want to look for clear, running water — somewhere between a babbling brook and a rushing river.

Avoid stagnant ponds or areas where there might be runoff (from livestock, urban areas, etc.) or debris. You’ll also want to find a safe place to refill, pump, or hang your gravity filter.

With some filtering methods, like chemical filters and tablets, you’ll want to wait longer to ensure that the water is clean if it’s below a certain temperature (or cloudy).

What’s the Difference Between Filtration and Purification?

Filters most commonly use a tube, pump, or gravity method of filtering. Purifiers use a combination of a tube or chamber with activated carbon or another chemical component to fight against one key difference: viruses.

All of the choices on this list protect against at least bacteria and protozoa, and many also protect against things like toxins, chemicals, and viruses. We recommend choosing the one that will work best based on your situation, budget, and preference.

How Long Does a Backpacking Water Filter Last?

The lifespan of a filter largely depends on the type of filter. Most hollow fiber or activated charcoal cartridges will need to be replaced every couple hundred uses, or after a certain number of liters have been filtered. Some filters, like the LifeStraw, can last for years, but when it’s run its lifespan you’ll need to buy a new one.

There are also some filters and purifiers that just need new batteries or to be charged.

Can Viruses Be Filtered Out of Water?

Yes! Purifiers like the Grayl Geopress Purifier are built especially to filter and protect against everything you could encounter, whether in the backcountry or in a third-world country.

As long as you are following the instructions on your filter or purifier, it will protect against whatever it’s rated for (usually something like 99.999999% of bacteria and 99.999% of parasites and microorganisms.)

dipping the grayl press water purifier into a clear mountain stream

How Much Should I Spend?

My top two considerations when buying gear like this are always: (1) how often I will be using it and (2) price. But an important third criterion for many is how long a filter will last. If you backpack or hike 9-12 months out of the year, you probably want to drop more dollars on a filter that has a longer lifespan.

And when all else fails, you can boil water to be safe. But let’s be honest — having a water filter on hand is much better.

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