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How to Select a Backpacking Water Filter and Treatment System

How to Select a Backpacking Water Filter and Treatment System
We tested 16 different methods of water filtration and purification.
Credit: Jessica Haist
Thursday April 23, 2020

Water is the essence of life. Our bodies are largely made up of water, and sufficient hydration is imperative to ensure safety and longevity at home, on the trail…anywhere. When you're out exploring either in the front or backcountry, carrying all the water you need can be exhausting and unnecessary. Snow, streams, lakes, ponds, rivers, and spring seeps are all water sources. Unfortunately, not all backcountry water is safe to drink. The easiest solution is to carry a water filter or purification system with you to keep you protected from harmful pathogens. But, before buying, it's important to know what to look for and buy a product that offers the conveniences you need based on how you prefer to travel.

backpacking water filter - eddy prepares to gather water from this scenic mountain stream in...
Eddy prepares to gather water from this scenic mountain stream in the Weehawken Basin of the San Juan mountains.
Credit: Amber King

Water Treatment

Floating in different water sources are contaminants invisible to the human eye. In North America, bacteria and protozoan cysts like Giardia and Cryptosporidium are the largest concern. In developing nations, more serious viruses like Hepatitis A may be present. What you can eliminate depends on your treatment system. So what treatment systems exist and what do they remove?

Purifiers vs. Filters

Purifiers differ from filters in technical effectiveness. When looking at different products, note if it is called a purifier or filter. Below we outline the differences in what each removes.


This system mechanically pushes water through an actual filter, straining out bacteria and protozoa based on size. It does NOT kill viruses. These are fine to use in North America, but be cautious with them while traveling abroad where viruses might be problematic.

backpacking water filter - here we take from an alpine lake high in the san juan mountains...
Here we take from an alpine lake high in the San Juan mountains, drinking directly from our dirty water collection bag, with the Sawyer filter on top.
Credit: Amber King


Purifiers are a system approved for eliminating viruses as well as bacteria and protozoa. These can be used anywhere in the world and are ideal if traveling abroad where water-borne viruses are a common problem.

backpacking water filter - the guardian purifier is at home anywhere in the world. here we use...
The Guardian Purifier is at home anywhere in the world. Here we use it in the pristine alpine meadows in the Sierra Nevada. While this technology is a little overkill for this environment, it's a great option for travel abroad in developing nations.
Credit: Jessica Haist

Filtration systems will also remove fine particulates, but not dissolved substances like salt from the water. It's important to note that saltwater cannot be filtered to make freshwater.

Types of Water Filter and Purifiers

There are several systems out there for filtering or purifying water. All the types fall into one of the six categories listed below. Below we outline the pros and cons of each system, and what each is ideal for. Categories include; pump filters, gravity filters, on-the-go systems, bottle filters, chemical treatment, and UV light.

backpacking water filter - the grayl geopress is an amazing bottle purifier that was able to...
The Grayl Geopress is an amazing bottle purifier that was able to make this yellow water, full of toxic chemicals and heavy metals, clear and drinkable.
Credit: Amber King

Pump Filters

backpacking water filter - a look at the relative sizes of other handpumps like the msr...
A look at the relative sizes of other handpumps like the MSR Guardian. The Katadyn Hiker Pro is much smaller, offering better functionality as a backcountry water filtration option for those who are weight conscious.
Credit: Amber King

These are widespread, and what people usually think of first when they think of water treatment. These devices cleanse water by pumping it through a filter that has a pore size that is too small for microorganisms to get through. You can find both filters and purifiers in this category.

Pros: Reliable, reaches all types of water sources
Cons: Takes time to pump, requires maintenance

Best Uses: Groups of 1 - 2 people, all types of water sources, backcountry travel

Gravity Filters

backpacking water filter - making some early morning breakfast after a short run at base camp...
Making some early morning breakfast after a short run at base camp with the Trail Base Gravity system.
Credit: Amber King

These products cleanse water by using gravity to push it through a filter, eliminating time-consuming pumping.

Pros: Easy and fast, versatile uses, in-line filter compatibility, ample storage capacity
Cons: Typically need something to hang the system from, lacks on-the-go travel options

Best Uses: Small to Large Groups, base camps, backpacking, medium to abundant water sources

On-The-Go Systems

backpacking water filter - a look at the two sawyer products that are great examples of...
A look at the two Sawyer products that are great examples of lightweight on-the-go filtration systems.
Credit: Amber King

These models treat water as you drink directly through a big straw, through the filter itself, or attaches to a compatible squeeze bag or bottle. The water is filtered as you sip, powered by your sucking force or by squeezing a small reservoir it comes with. These filters come in all forms.

Pros: Lightweight, fast & easy, super-duper packable
Cons: Water flow is usually not very fast, water storage requires another vessel

Best Uses: Lightweight travel missions, solo-use, all types of water sources

Bottle Filters

backpacking water filter - the grayl ultralight purifier comes with a built-in filtration...
The Grayl Ultralight Purifier comes with a built-in filtration cartridge that purifies water.
Credit: Amber King

This system uses a filter built into the bottle. Working like a french press, you push the water through the system. The bottle is your filter and your drinking reservoir. Alternatively, the filter is in the bottle and you drink right through it.

Pros: Lightweight, no additional parts, packable
Cons: Hard to filter by pressing

Best Uses: Travel, short backpacking missions, solo use.

Chemical Drops and Tablets

backpacking water filter - chemical treatments that have their own set of pros and cons.
Chemical treatments that have their own set of pros and cons.
Credit: Amber King

Drops and tablets purify water by adding a chemical to it. They have the advantage of killing viruses in addition to bacteria and most protozoa. However, many of these treatments do not kill Cryptosporidium a common pathogen in North America. As a result, this treatment is ideal in conjunction with a filtration system that can remove it.

Pros: Lightweight, inexpensive, kills most pathogens
Cons: Long treatment time, adds a taste to the water, doesn't remove particulates

Best Uses Emergency treatment, lightweight missions, all water sources, solo to group use.

UV Light Purifiers

backpacking water filter - a uv light purifier that is excellent for international travel...
A UV light purifier that is excellent for international travel. Especially when you want to make sure the ice in your cocktail isn't contaminated.
Credit: Amber King

These mechanical devices purify water by zapping it with ultraviolet light. This scrambles the DNA of these invisible pathogens, not allowing them to reproduce. As a result, the water is clean and safe to drink.

Pros: Quick and easy to use, purification system
Cons: Doesn't remove particulates, needs battery life, generally unreliable

Best Uses: Travel to international countries

Effectiveness of Pathogen Removal

The world we live in is well-traveled by all sorts of potential sources of contamination. Sources of water pollution are diverse and wide, ranging from fecal matter from both humans and animals to chemical contaminants, a function of dirty industrial practices, all over the world. In the past, we've thought that getting away from civilization meant drinking pristine water, free of contamination, without the need for filtration.

backpacking water filter - we take a moment to enjoy a cool sip of water...upstream from...
We take a moment to enjoy a cool sip of water...upstream from obvious water contaminants, of course.
Credit: Ian McEleney

However, times are changing. Remote backcountry routes are seeing more traffic, and now it's critical to treat your water more than ever. In general, it's easy to identify sources of contamination. If you see other humans, mountain goats or other big animals around, you might be at risk as their fecal matter can get into pristine sources, transmitting pathogens. If you travel internationally, assume water should be treated to be safe. So what can affect you? Below we outline pathogens to be aware of and which systems are effective against them.

Water Pathogens

Bacteria: E. coli, Shigella, and Campylobacteriosis, as just a few examples, can also live in water. These are the easiest pathogens to filter out and treat. Bacteria are larger than protozoans and about 10X the size of a virus.

Removed by: All systems of filtration and purification

backpacking water filter - this slow-flowing river in northern ontario is probably ripe with...
This slow-flowing river in Northern Ontario is probably ripe with Giardia and other bacteria. Luckily, most treatment systems can destroy these pathogens.
Credit: Amber King

Protozoa: This group includes the most commonly feared of all waterborne illnesses - Giardia and Cryptosporidium. These are single-celled parasitic organisms that cause serious intestinal problems, with symptoms appearing anywhere from two days to two weeks from ingestion. These organisms can live in cold water for weeks or months at a time. Cryptosporidium has a hard protective outer layer, which makes it resistant to many types of water treatment. Filters with an absolute pore size of 0.2 microns can get rid of these organisms.

Both Giardia & Cryptosporidium

Removed by: Chloride Dioxide Drops (Aquamira Drops) (not other chemical treatments), UV light, Filters with a pore size smaller than 0.2 micron.

Giardia but NOT Cryptosporidium

Removed by: Other types of chemical treatment (i.e., Iodine tablets, Sodium dichloroisocyanurate)

Viruses: Examples include Hepatitis A and Rotavirus. Viruses are not thought to be a significant threat when hiking and traveling in the U.S. and Canada, but on international trips, they become a much larger concern. Viruses are tiny, so they are not strained out with most filters unless their pore size is as small as 0.02 microns. Purification systems are the only ones that can remove these.

backpacking water filter - aquamira drops are a lightweight solution to purifying water in the...
Aquamira drops are a lightweight solution to purifying water in the backcountry.
Credit: Jessica Haist

Removed by: Chemical treatment, UV filters, purification filters (w/ a pore size smaller than 0.02 microns), Ion Exchange Technology (Used in Grayl Purifiers)

Leave No Trace

To ensure that you're not adding to the contamination of water sources in your favorite exploration location, there are a few easy Leave No Trace (LNT) rules to follow:
  • Poop 200 meters from any water sources — If you are going to be leaving a fine gem in the backcountry, it's important to make sure you are far away from water sources. Your fecal matter, is, unfortunately, not as pristine as a gem and could be carrying bacteria or harmful pathogens.
  • Bury your poop — Carry a small shovel with you and bury your waste about 8-inches deep. This isn't a random depth. It's at this depth that hungry bacteria are looking to decompose your waste, which will ultimately return it to the Earth more quickly. Any shallower than this and your waste will sit there, with potential for contamination, for a longer period.
  • Wash your hands after using the bathroom — To avoid getting sick, wash with soap and water, especially if you're cooking for a group of people.

Follow these simple rules, and you'll be tending to the health of those around you and yourself.

User Considerations

When purchasing a filtration or purification system, there are several other factors to consider in your purchase. Below we outline some things to consider before buying.

Where are you going?

Be sure to research you are headed off to determine if you need a filtration or purification system. Filters are typically much cheaper and will work for most adventures in North America. However, if you're keen on international travel, a purification system is probably a better option.

backpacking water filter - a beautiful sunset in mexico makes for drinking cocktails on the...
A beautiful sunset in Mexico makes for drinking cocktails on the beach a must. However, it's important to know your water will be healthy to drink. Here we use a purifier as we don't want to get a viral infection while traveling.
Credit: Amber King

What are you doing?

Based on your activity, you might choose a different water filter. For example; a fast packer who is looking to shed the most ounces is going to make a different choice than somebody who is car camping where weight doesn't matter the most. Below, we outline some activities and provide some recommendations.

Backpacking: Given that you are carrying everything with you, you will want to consider the weight and packability of all your items. For example; thru-hikers that are taking on 1000's of miles may opt to go with a super lightweight chemical treatment that can kill most things.

backpacking water filter - here we take adventures into the jungle where loads of pathogens may...
Here we take adventures into the jungle where loads of pathogens may exist. Since its an overnight missions, we're not too concerned about weight.
Credit: Amber King

However, if you're just out for a few days and you're traveling with a large group, you can split the water filtration system that weighs a few more ounces. In that case, you may want to consider a highly efficient and fast filtration system.

Fastpacking or Trail Running: It's all about going light. In this case, we'd choose the lightest and safest options out there. Chemical treatment is a great option here. However, it doesn't yield water quickly, requiring about a half-hour of waiting time. On-the-go filtrations units offer better durability and filter water instantly. Look for those with interchangeable bottles, so you can choose which one you want to squeeze to get water and hold in your hand or hydration vest.

backpacking water filter - fastpacking on the remote hornstrandir nature reserve in iceland is...
Fastpacking on the remote Hornstrandir Nature Reserve in Iceland is a perfect utility of the ultralightweight MSR Aquatabs that weigh next to nothing.
Credit: Amber King

Bikepacking: If you like your current bottle while biking, there are adaptor kits out there that can fit the bottles you love best. These turn your bottle into a filtration system. They are super lightweight and easy to pack about.

International Travel: Be sure to carry a purification system or chemical treatment when traveling abroad. Since viruses abound in these areas, it's essential to be protected from them.

What are your water sources like?

Before embarking on any trip, it's important to research where your water sources will be, and what you can expect of them. Water sources that are few and far between will require additional storage along the way. If you can go from one source to another, you might be alright with an on-the-go system that doesn't need storage. You should also consider the source of your water source. If it's a lake, it'll probably run all summer. But if it's snowmelt that melts in the Spring, it may dry up by Summer or Fall. Consider this when choosing your filter.

backpacking water filter - it's important to know your water sources so you can determine how...
It's important to know your water sources so you can determine how much you need to carry to the next stop.
Credit: Ian McEleney

Is the water turbid?

If you're planning on traveling anywhere in the desert where sediment is in high concentration, this is a serious concern. Water that has high amounts of silt and sediment will clog filters. It doesn't matter the type of filter or system. If you plan a trip to the Grand Canyon and the only source is the Colorado River (one of most swollen rivers in the world) you're going to run into problems.

backpacking water filter - this gross puddle, like many water sources in the desert, is...
This gross puddle, like many water sources in the desert, is destined to clog your filter...eventually.
Credit: Amber King

Pro Tip: If you're in an area with high turbidity, be sure to bring an extra bag (like a gallon ziplock) where you can allow the water to settle out. After the silt has settled to the bottom (this may take half an hour or more), decant the clear water off the top of the bag into a bag for filtration. This helps avoid clogging your filter on the go.

How much are you willing to spend?

There are systems out there that range widely in price. Some of the best options are typically more expensive with their own set of pros and cons. Chemical water treatment is by far one of the cheapest options, but comes with the caveat that it'll change the taste of your water, won't get rid of particulates, and requires a waiting period. Other options can rise into the hundreds of dollars like the MSR Guardian. This is like the Porsche of water filters that can do pretty much everything. So what are you willing to invest? Be sure to look at our Best Buy and budget recommendations, as well as comparing each model's performance to its price.

What's in your Filter?

In your filter, there will be some filtration media that eliminates microorganisms and other contaminants from your water. Some filters also have activated carbon. Below we educate you on the different types you might come across in your shopping.

Filter Media

There are many filtration options out there. Here's some information on the different types that you might see in your research.

A look at the replaceable filtration cartridge that can filter out...
A look at the replaceable filtration cartridge that can filter out viruses as well as other water-borne pathogens.

Ceramic: This is an earthen material (yes, the same kind of stuff your favorite coffee mug is made out of) that has a long life and can be cleaned many times before being replaced. Unfortunately, it can get clogged easily. But on the bright side, scraping it clean is easy. Ceramic filters can also come with a carbon core, which helps to remove chemicals from water.

Fiberglass: A material that is more fragile than ceramic, but still effective at eliminating particles.

Hollow Fiber: Made up of hollow U-shaped microtubes, this filter allows water through tiny pores and into the core, where pathogens are strained out.

Silica Depth: Using finely grained silica sand, this filter works by having multiple levels of different sized grains, going from largest to finest. It catches different sized particles and organisms as water is pushed through its levels of density.

Activated Carbon

Activated carbon can be found in many filters and is used to remove other contaminants like pesticides, heavy metals, smells, and the like. If you're concerned about any of these, be sure to find an option with activated carbon.

Filter Features

There are many different features that are found with several filters. For example; some have the ability for awesome storage capacity while others don't. Some have adaptability that allows compatibility between bottles, water bladders, and other in-line systems. We outline what's going on with those below.


If you're in a place where you need to pump a lot of water because your next water source won't be a few miles, it's important to look for a filter that can move a lot of water quickly. Gravity filters are the fastest solution to these problems. Some of these systems come with built-in storage with bags that are clearly marked “clean” or “dirty” so you can store your water effectively. Storage may not matter if you're in a place where water is plentiful.

backpacking water filter - we use the msr dromedary as a common clean water storage bag with...
We use the MSR Dromedary as a common clean water storage bag with gravity systems that don't come with their own “clean” water bag.
Credit: Amber King

In-line Adaptability

Some filters can literally clip right into a tube line and provide filtration on the go. While these systems are a cool idea, they typically reduce the flow of water, rendering them almost useless.

backpacking water filter - sucking can be a pain when using some filtration systems in-line...
Sucking can be a pain when using some filtration systems in-line with a hydration bladder.
Credit: Edward Kemper

Most in-line adaptable filters can be used with hydration bladder set-ups and gravity filters. Depending on the filter, you will have varying results for the rate of flow from the dirty water bag to your clean reservoir.


backpacking water filter - grabbing water from a shallow puddle on a trail run in the desert is...
Grabbing water from a shallow puddle on a trail run in the desert is a perfect application for the on-the-go Sawyer Mini.
Credit: Amber King
Consider your personal uses and needs when looking at a water treatment system. There are many options out there with different systems posing a suite of different pros and cons. We hope we've been helpful in your search for a fantastical water treatment system that suits your needs.