The world's most in-depth and scientific reviews of outdoor gear

How to Select a Backpacking Water Filter and Treatment System

We tested 16 different methods of water filtration and purification.
Monday May 6, 2019

The human body is about 60-70 percent water by weight. The amount of water a person needs per day varies depending on the temperature, humidity, altitude, and the amount of physical activity the person is engaged in. Carrying all the water you need for a trip can be exhausting as one liter of water weighs about one kilogram. Fortunately, we can usually find the water we need in the backcountry from streams, lakes, snow run-off, or spring seeps. The problem is that backcountry water may not be safe to drink without treatment. Thus, an easy solution is to carry a treatment system that can protect you from harmful, water-borne pathogens. You must carry what you need to get to the next water source.

Water treatment is an important consideration  especially when you are taking from questionable and stagnant sources.
Water treatment is an important consideration, especially when you are taking from questionable and stagnant sources.

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.

Filters: 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.

Purifiers: 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 problem.

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.
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.

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.

Water Treatment Options


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 filter, gravity filters, on-the-go systems, bottle filters, chemical treatment, and UV light.

All the methods to treat and/or filter for viruses in this review.
All the methods to treat and/or filter for viruses in this review.

Pump Filters — 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.

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.
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.

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

Example: Katadyn Hiker Pro — Water Filter, MSR Guardian Purifier — Water Purifier

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

Making some early morning breakfast after a short run at base camp with the Trail Base Gravity system.
Making some early morning breakfast after a short run at base camp with the Trail Base Gravity system.

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

Example: Platypus GravityWorks 4L — Editor's Choice or Katadyn Gravity Camp 6L — Best Buy

On-The-Go Systems — 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.

A look at the two Sawyer products that are great examples of lightweight on-the-go filtration systems.
A look at the two Sawyer products that are great examples of lightweight on-the-go filtration systems.

Pros: Lightweight, fast & easy, super duper packable
Cons: Can't typically store much or any water, water flow is usually not very fast

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

Example: Katadyn BeFree 0.6L — Our Top Pick, Sawyer Micro Squeeze — Editors' Choice

Bottle Filters — This is a new type of filtration system with the 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.

The Grayl Ultralight Purifier comes with a built-in filtration cartridge that purifies water.
The Grayl Ultralight Purifier comes with a built-in filtration cartridge that purifies water.

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

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

Example: Grayl Ultralight Water Purifier

Chemical Drops and Tablets — 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 this cyst is tricky. As a result, this treatment is ideal in conjunction with a filtration system that can remove it.

Chemical treatments that have their own set of pros and cons.
Chemical treatments that have their own set of pros and cons.

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.

Example: Aquamira Water Treatment Drops

UV Light — These mechanical devices purify water by zapping it with ultraviolet light. This scrambles the DNA of these invisible pathogens, not allowing them to reproduce.

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.
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.

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

Best Uses: Travel to international countries

Example: SteriPEN Ultra.

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.

Taking a break on a hiker  we take a moment to enjoy a cool sip of water...upstream of obvious water contaminants.
Taking a break on a hiker, we take a moment to enjoy a cool sip of water...upstream of obvious water contaminants.

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 international, 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, Dysentery, 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

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 Rotovirus. 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.

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.

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.
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.

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 a 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 like the Aquamira Water Treatment Drops. If you're traveling solo, this is a great option.

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.
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.

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. Gravity filters like the Platypus Gravity Filter are a great option here. This weighs a few ounces but can filter way more water much more quickly. Plus it can double as a handwashing station or solar shower.

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. However, on-the-go filtrations units that offer more durability like the Sawyer Micro provide filtered water instantly. The Katadyn BeFree is less durable, but both are great on-the-go filtration systems that focus on eliminating weight with the affinity to filter out particles, something chemical treatment can't do.

Fastpacking on the remote Hornstrandir Nature Reserve in Iceland is a perfect utility of the ultralightweight MSR Aquatabs that weigh next to nothing.
Fastpacking on the remote Hornstrandir Nature Reserve in Iceland is a perfect utility of the ultralightweight MSR Aquatabs that weigh next to nothing.

Bikepacking: If you like your current bottle while biking, there are adaptor kits out there can fit the bottles you love best. These turn your bottle into a filtration system. They are super lightweight and easy to pack about. Check out the Lifestraw Universal Bottle Adaptor Kit, for its versatility.

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. If you plan on just hiking travel, consider the SteriPEN or the Ultralight Purification System by Grayl.

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 snow melt that melts in the Spring, it may dry up by Summer or Fall. Consider this when choosing your filter.

It's important to know your water sources so you can determine how much you need to carry to the next stop.
It's important to know your water sources so you can determine how much you need to carry to the next stop.

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.

This gross puddle  like many water sources in the desert  is destined to clog your filter...eventually.
This gross puddle, like many water sources in the desert, is destined to clog your filter...eventually.

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 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 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. For example; the Grayl Ultralight Purifier uses this to create new, clean, water.

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.

Storage


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 like the Katadyn Gravity Filter are the fastest solution to these problems. Some of these systems come with built-in storage. For example, the Platypus and MSR gravity options both have bags that are clearly marked "clean" or "dirty" so you can store your water effectively and keep contaminated water separate from clean. Storage may not matter if you're in a place where water is plentiful.

In-line Adaptability


Some filters can literally clip right into a tube line and provide filtration on the go. For example, you can plug your hydration bladder into the Aquamira Frontier Max. While these systems are a cool idea, they typically reduce the flow of water, rendering them almost useless. 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.

We enjoy another sunset in the wet and wild world of Iceland. Despite how pristine this land is  we know water treatment is paramount to staying healthy while traveling and backpacking abroad.
We enjoy another sunset in the wet and wild world of Iceland. Despite how pristine this land is, we know water treatment is paramount to staying healthy while traveling and backpacking abroad.

Conclusion


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.


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