Water Filter & Treatment System for backpacking trips

In a backpacking trip, finding water source, and treating water for drinking and cooking is important.  I usually need 6 liters of water daily, and I need additional 3 liters of water for my dog (an 80 lb. Rottweiler).

I always bring my Katadyn Hiker Pro water filter with me as the main water filter, and will bring Aguamira Water Treatment Drops (Chlorine Dioxide) as a backup.  Aguamira contains 2 1-oz bottles (Part A and part B) to treat 30 gallons of water.

I find the quoted article “How to Select a Backpacking Water Filter and Treatment System” by McKenzie Long very informative.  I quote the entire article in the following.  The article is on this web page 

I quote the article by McKenzie Long:

Selecting a water treatment system is even more overwhelming than selecting proper footwear to hike in, which is a much talked about topic. There are numerous factors to consider, from the basic categories of size, weight, and treatment time, to more complicated categories such as filter medium, longevity of the system, and what types of organisms each system is effective at eliminating. Combining and comparing all of these options can make your head spin. Here, we give you straight-up advice on what to consider, what we think is the most important, and which products we think are the best.

Dan Sandberg uses the Katadyn Hiker Pro to filter water from a running stream, Rocky Mountains, Colorado.

Credit: Max Neale

Why Treat Water?

First of all, what are you even trying to eliminate from your water with a treatment system, and is it even necessary to treat water?

Recent research has concluded that backcountry sources at high elevations are probably cleaner than we once thought. It may not be necessary to treat all water that you come in contact with. The clincher? It is impossible to tell by sight if water is contaminated. A good rule of thumb is that if you are at a high elevation where there is no cattle grazing, no pack animals, and little human traffic, then you are probably all right. However, if you are along a heavily traveled trail, it is wiser to treat your water than to risk it. What are the risks? Here is a list of water-borne pathogens that could cause some serious intestinal tract discomfort.

Water is a necessary part of hiking, and clean water makes the entire experience more enjoyable.

Credit: Veronica Long


Protozoa: This group includes the most commonly feared of all water-borne illnesses – Giardia and Cryptosporidium. These are single-celled parasitic organisms that cause intense 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.

Bacteria: E. coli, Dysentary and Campylobacteriosis, as just a few examples, can also live in water. These are the easiest pathogens to filter out and treat, since they are much larger than viruses.

Viruses: Examples include Hepatitis A and rotovirus. Viruses are not thought to be a large threat when hiking and traveling in the US and Canada, but on other international trips, viruses become a much larger concern. Viruses are extremely small, so they are not strained out with most filters.

Once you are aware of the risks of water-borne pathogens, the next step is learning how to prevent these illnesses.

Purifiers vs. Filters

Filters and purifiers have technical differences in effectiveness. A filter mechanically pushes water through an actual filter, straining out bacteria and protozoa, but typically does NOT kill viruses. A purifier is a system that is approved for eliminating viruses as well as bacteria and protozoa, and usually involves chemicals, though UV light functions as a purifier as well. An example of a filter would be the Katadyn Hiker Pro, and a purifier would be the Aquamira Water Treatment drops.

What System Works on What Pathogen?

Unfortunately, there is no miracle system that is the perfect solution, though some systems come pretty close. Often times, manufacturers recommend carrying a filter AND a chemical treatment because that is the fastest and most efficient way to eliminate all harmful possibilities from water. Here is our quick and easy breakdown on what types of systems kill what types of pathogens and vice versa:

Effectiveness of Systems:

Filters: Eliminate bacteria and Cryptosporidium, but not viruses. They strain out particulate and usually improve the taste of the water.

Chemical Treatments: Eliminate bacteria and viruses, eliminate Cryptosporidium usually only after extended incubation time, does not strain out particulate, and usually negatively affects the taste of water.

UV Purifiers: Effective against all pathogens: bacteria, viruses, and protozoa. UV treatments do not actually kill pathogens, they simply scramble the DNA of the organisms so that they cannot reproduce. Be careful of treating water and then letting it sit in visible light for a long period of time, because the organisms can reactivate. They do not strain out particulate unless you use a pre-filter. Do not change the taste of the water. One other noteworthy detail is that the EPA approves of the UV process as a purifier, which is used in many large commercial water treatment plants; however, the organization does not actually approve specific UV devices that hikers carry.

What Eliminates Certain Pathogens?

Cryptosporidium: Filters eliminate, UV purifiers effectively disable, chlorine dioxide tablets eliminate after four hours and drops after one hour, iodine does not work.

Viruses: Eliminated by iodine, chlorine dioxide, and UV purifiers, but not filters.

Bacteria: Eliminated by all systems: filters, chemical treatments, and UV purifiers.

Particulate: Okay, so this isn’t a harmful pathogen, but silt and dead bugs do not make for appetizing water. Filters, or separately purchased pre-filters, are the only things that strain particles out of your water.

The Effectiveness Bottom Line:

So now that we have laid it all out for you, what does that mean you should choose? The absolute safest way would be to combine a chemical treatment, such as Aquamira, with a lightweight filter such as the MSR Hyperflow Microfilter. This means you can quickly strain out particulate and Cryptosporidium, but the chemicals can also eliminate viruses. However, carrying two systems is unnecessarily heavy and complicated. Take into consideration where you will be traveling. Hiking through the High Sierra? You would probably be fine with just one system, either a filter or chemical, because the water there is clear and relatively clean. Filters are thought to be adequate for backcountry travel in the US and Canada. Traveling internationally? You will want something that kills viruses, so ditch the regular filters and either bring along the First Need XL, theSteriPEN, or a chemical treatment to make sure you eliminate all pathogens.

Other User Considerations


After effectiveness, the primary concern of a hiker is how much the treatment system weighs. Common systems have drastic variance in weight, ranging from a couple ounces to over 23 ounces. Depending on your activity, weight can be of more or less concern. If you are hiking long distances, we suggest a small and light chemical method, such asAquamira Water Treatment Drops. If you are traveling internationally and are setting up a basecamp, a heavier but highly effective method such as the First Need XL would be an ideal choice. For the average hiker in the US, we suggest a filter, either gravity-fed like the Platypus GravityWorks or a pump like the MSR Sweetwater, because these are effective without being too heavy and also do not involve adding chemicals to your water and your body.

Comparison of water treatment sizes unpacked.

Credit: McKenzie Long

Time Before Drinking

The time it takes for different methods to treat drinking water varies wildly, from 90 seconds for a liter from the SteriPen Journey to half an hour for Potable Aqua Iodinetablets to 15 minutes to four hours for the Katadyn Micropur tablets. If you are on any kind of backpacking trip, whether it’s a weekend trip or a thru-hike of the entire Pacific Crest Trail, time is of the essence, and you will not want a treatment method that takes a long period of time. You will need to get water as you go, and cannot afford to waste time sitting around waiting for your water to be ready.

If you are traveling internationally to some very sketchy and contaminated water sources, or you’re posted up at a campsite, some of the longer methods would be perfect. If you are just looking for an emergency treatment method to leave in your pack, a chemical treatment would work fine.

In general, filters, either gravity-fed or pumps, work faster than chemical treatments, though chemical treatments are lighter and smaller to pack. UV treatments are also quick.

Other Filter Details to Consider

Squirting the super-soaker-esque MSR Hyperflow Microfilter.

Credit: Luke Lydiard

Ability to Treat Large Quantities of Water

If you are a single hiker on a short trip, then this is not a huge concern. Scooping water into your Nalgene and treating with a SteriPEN will work just fine. However, if you are bringing one treatment method for a group of people, or you want the ability to treat a lot of water for cooking at base camp, or there are limited water sources so you need to be able to collect and treat a lot of water at once, it is worth taking into consideration how to treat a lot of water. In these situations, collecting and treating water with the SteriPEN one bottle at a time is tedious and inefficient. Pump filters work well in these scenarios because they can easily treat as much or as little water as needed. The gravity-fed filters have the ability to collect and treat a lot of water quickly, which is great for groups.

Filter Medium

The filter is the actual material that catches the organisms in your water, and there are multiple types on the market. Here is a brief list of the types:

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 it is easy to scrape clean. Ceramic filters can also come with a carbon core, which helps to remove chemicals from water. Example: MSR Miniworks EX.

Structured Matrix: This is a dense and honeycombed material that can strain out really tiny pathogens. Example: First Need XL.

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

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

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. Example: MSR Sweetwater Microfilter.

Micron Size

If you are shopping for a filter, a techy detail that you will continually stumble across is micron size. This is a measurement of the pore size in the filter media. Essentially, the smaller the pore size, the more pathogens the filter can strain out. A simple rule of thumb is that the smallest bacteria is 0.2 microns, so a filter should be around that size or smaller to be the most effective.

Durability/Uses Before Maintenance

If you have chosen a pump filter as your treatment method, and you plan to bring it with you on multi-day trips, it is important that you look for a pump that is field maintainable, meaning you can service it on your own in the backcountry if it gets clogged. For example, ceramic filters need to be scraped relatively often, but this is easy to do. Most other pump-filters are engineered to be easy to back-flush to remove clogs, but it is worth investigating how complicated this process will be so you don’t get left high and dry on your over-nighter.

It is also worth noting how long a filter will last before it needs to be replaced. Ceramic filters can filter up to 2,000 liters, while other types of filters may only be effective to around 500 liters. You can purchase replacement cartridges once the filter has run its course.

Electronic treatment methods such as a UV purifier have an entirely different concern: battery life and bulb life. UV lamps typically last around 8,000 treatments, which is excellent life. However, batteries need to be replaced every 40-100 treatments.

Advice From Thru-Hikers
For those of you ultralight or long distance hikers, we talked to some Appalachian Trail thru-hikers to see what their thoughts were on water treatment methods, and ultimately what they prefer to use.

Collecting water on the Appalachian Trail.

Credit: Veronica Long
The most important features to a long-distance hiker striving for a light pack are not all that different from our general considerations: weight, the time it takes to treat a liter, price, and upkeep. Not surprisingly, they said all the filters were too heavy and they would not consider carrying them. Initially the SteriPEN was an attractive option, but the lithium batteries didn’t last long, were expensive, and were hard to find in towns along the Trail.

The most popular method along the trail was by far Aquamira Water Treatment Drops. This system is incredibly light, inexpensive, and can be used over the long-term, unlike iodine. So many hikers found it to be ideal.


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