The Best Backpacking Water Purification and Filter Systems

Water Treatment in the Backcountry
The human body is about 60-70% water by weight. The amount of water one needs a day varies widely depending on temperature, humidity, altitude, and the amount of physical activity you are engaged in. At rest, the Mayo Clinic estimates men need about 3 liters of water a day, women 2.2 liters. But, if you are exercising in the mountains, that may increase by 50% to over 4 liters for men, and more than 3 liters for women. At a weight of 2.2 lbs per liter, most of us don't want to carry enough water for a 4 day backcountry trip in our packs (over 35 lbs for men, 26 lbs for women).

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. Giardia is one of the more well known risks to backcountry water sources, a protozoan parasite readily transmitted via the feces of deer, cattle, beavers, and other mammals. But, other contaminants such as bacteria, cysts, and a particularly nasty protozoan called Cryptosporidium, are also risks in US backcountry areas. And, internationally, virus contamination is not uncommon. The answer is to carry a water filtration device that can remove these contaminants, and simply cleanse water as you need it. Water treatment is much lighter than bringing all the water you need. And with it, you need only carry enough water to get you from one source to the next.


Types of Water Treatment Systems
In this review, we examined 15 different water treatment systems to find the very best. Four different types of systems were represented:

• Pump filters — cleanse water by pumping it through a filter

• Gravity-fed filters — cleanse water by using gravity to push it through a filter

• Drops and tablets — purify water by treating it with a chemical

• UV light — purify water by treating it with ultraviolet light

Please refer to our buying advice article, How to Select a Backpacking Water Filter and Treatment System, for more detailed background information on the need to treat backcountry water, contamination sources, and the advantages and disadvantages of different types of treatment methods.

Criteria for Evaluation
When evaluating various treatment systems, the most important factors we considered were reliability and effectiveness, because if your system doesn't work, then there is no use in carrying it. Also, different systems treat for different hazards, and it is helpful to know what your system will be treating for. The second most important factor was weight, because when traveling in the backcountry it is desirable to have a compact and lightweight system and not to have a heavy and clunky filter weighing you down, or you are likely not to even bring it with you. Next, we compared how long it takes the system to work before you can drink, and this was where we noticed a large difference between methods. We also evaluated how well each system can treat large quantities of water, so groups or hikers needing a lot of water at base camp can select an appropriate treatment method. Read on for more details and comparisons as well as a few other considerations.

Reliability/Effectiveness
Reliability and effectiveness are related, but slightly different. Effectiveness measures what the treatment system actually eliminates. Reliability is a measurement of how heavily you can rely on the system you are carrying, and if you are likely to need a backup system. Simple systems like the Katadyn Hiker Pro and the MSR Sweetwater are easy to rely on. More complicated systems like the UV light purifiers are slightly less reliable because of factors such as batteries or bulbs dying. We found our most reliable systems to be ones where not many things can break or go wrong so they are easy to rely on: Platypus Gravityworks, Aquamira Water Treatment Drops, Sawyer Squeeze, and Katadyn Micropur Tablets. The least reliable were the SteriPEN models due to reports of malfunctioning, and the somewhat short battery life, which make us hesitant to bring it on multi-day trips.

Different water treatments are effective on different types of organisms. The main difference in effectiveness in the systems we reviewed is whether or not a system treats viruses or the hard-shelled (meaning hard to kill) protozoa Cryptosporidum. Read our How to Select a Water Treatment System article for more in depth details on this topic.


Systems That Treat Viruses
If you plan to travel internationally where water sources have a much higher likelihood of virus contamination, a system that treats viruses is strongly recommended. Here is a quick look at six systems that do treat viruses:

• UV light systems — SteriPEN and CamelBak All Clear

• Iodine - Potable Aqua

• Chlorine Dioxide (tablets or drops) — Aquamira and Katadyn Micropur

• First Need XL Filter

All the other filters remove bacteria, cysts, and protozoa like Cryptosporidium (which some of the chemical treatments do not eliminate), and particulate (which many of the above treatments do not remove.) Usually, protection against bacteria, protozoa, and cysts is all you need for hiking in the mountains of US and Canada. Virus protection is generally considered an international travel feature.

Weight
Weight is a huge concern since you will most likely be lugging your water treatment system with you on long hikes. Hiking is more enjoyable with less weight on your back, so wisely selecting a treatment system that does not weigh more than your sleeping bag is a huge plus. Rather than go by the manufacturer's specs, we weighed each system individually, including all the accessories and carrying cases that would be brought with them, to give you the most accurate idea of how much the system actually adds to your pack.

The lightest systems are obviously the chemical treatments, which are compact and almost unnoticeable in your pack. Aquamira Water Treatment Drops only weigh 3 oz with their carrying caps. If you only want to bring a couple individually wrapped chlorine dioxide tablets, the Katadyn Micropur tablets only weigh 0.02 oz each, and the iodine plus taste neutralizers weigh 2.27 oz for both bottles. Next comes the SteriPen Adventurer Opti at 4.61 oz and the Sawyer Squeeze for 5.1 oz including all 3 collapsible bottles, and then the Platypus Gravityworks at 11.9 oz. Keep in mind that with the SteriPEN, you are likely to need to carry a heavy, hard-soded bottle like a Nalgene, which adds weight not included in this measurement, whereas the Sawyer Squeeze uses very lightweight bottles. The heaviest and bulkiest systems were by far the First Need XL at 22 ounces and the Katadyn Pocket at almost 24 ounces.

Time Before Drinking
Imagine this common scenario: You are backpacking and come to a stream crossing where you can refill water. Your next water source will not be for another 10 miles, so you need to maximize this source. Ideally you will drink a good amount of water now, and fill up all of your bottles and/or bladder reservoirs now to carry with you to drink until the next source. This is when the time it takes to purify water really matters. The Katadyn Micropur chlorine dioxide tablets take four hours to effectively purify water, and there is no realistic way you will waste your day waiting for the tablets to activate. Even Aquamira drops, our lightest system, takes an hour to fully treat for everything. Both of these chlorine dioxide systems kill most pathogens in the first 15 minutes, but that still requires a wait time that cuts into precious hiking hours.

The most immediate systems were the Aqua Vessel Insulated Filtration Bottle and the Sawyer Squeeze, where you can drink directly through the filter. However, the water flow through these filters is very slow. Most pumps can filter a liter in a little over a minute, which is preferable, and they can treat unlimited amounts of water, unlike the systems that are limited by a specific bottle or container.


The fastest system actually surprised us: the Platypus Gravityworks. It seemed like this system would require the most waiting around, but in fact, it worked the quickest, taking 1.05 minutes to filter one liter and 4 min 50 sec for an entire gallon. And better yet, you don't have to actually sit there and pump it, so you can fill it up and let it start working while you take a snack break or set up camp. Even though chemical treatments are simple, the pump filters are actually the best for a hiker on the go.

Ease of Use
We measured ease of use based on how intuitive each system was, how many steps each one requires to set up and treat water, as well as considering the frequency of maintenance and the complication of the back-flushing process.

The chemical systems require no maintenance whatsoever, and typically involve adding to water and waiting. It doesn't get much more simple than that.

The Aqua Vessel is maybe the easiest filter system: fill and drink. The runner-up for ease of use is the Platypus Gravityworks. The process of filling of the dirty bag, attaching the hoses, and waiting for it to filter is very painless. It has a three second back-flush process that involves inverting the clean bag over the dirty bag for a moment and no complicated disassembly.

The Miniworks, the Pocket, and the Hyperflow lost points for having complicated maintenance routines. The MSR Hyperflow, though easy to pump water, has a rather complicated back-flush process that involves reversing small valves, and it is directed to be done every 8 liters, which is quite often. Both the Miniworks and the Pocket are fairly intuitive to open up and scrape clean the ceramic filter, but this process, which also needs to be done fairly often, can be a pain.

The SteriPEN is very simple to use: you push a button and the screen smiles at you when it is finished. The main concern with this purifier is that the batteries need to be monitored and replaced frequently.

Durability/Uses Before Maintenance
The Miniworks, Katadyn Pocket, and Platypus Gravityworks last quite a while before needing a replacement filter, treating 2000 liters, 13,000, and 1500 liters respectively. The Sawyer Squeeze, according to its specs, can last for a million gallons, which is a lifetime of water treatment. The MSR Hyperflow directs the user to perform frequent back-flushing, but the filter lasts for 1000 liters before needing a replacement.

The filter with the shortest life is the Aqua Vessel, which treats approximately 370 liters, followed by the First Need XL, which treats around 560 liters.

The only system that had reported issues of durability was the SteriPEN, which one pair of hikers said was ruined after getting rained on, and other users reported random malfunctions.

Taste
Though taste is not a huge factor to consider when purchasing a water treatment system, there is a noticeable difference between treatment methods. The chemical treatments all change the flavor of water slightly. Iodine is famously horrible, but the taste-neutralizing tablets do a fairly good job of counteracting it. Chlorine dioxide does not add an entirely unpleasant flavor to water, but it has a small background taste to it.

Most filters actually improve the taste of water by cleaning out chemicals and heavy metals. The SteriPEN is the one system that doesn't change the flavor at all, positively or negatively.

Editors' Choice Winner: Platypus GravityWorks
As we performed our tests on the multiple filters contained in this review, we were surprised by the results. Unexpectedly the Platypus GravityWorks Water Filter pulled into the lead, earning the status of Editors' Choice by being the fastest filtering system, lightweight, and very simple to use. It also requires little to no maintenance with a filter effective for 1500 liters and no moving parts that could break. It is one of the most versatile systems because it gives you the option of treating small or large amounts of water quickly, so it can be used for a camp of multiple people or just a single hiker. It does not treat viruses, but we find this filter to be extremely useful and effective for hiking in the backcountry. We also like to have a reliable system that does not involve ingesting chemicals.

Top Pick Award for Ultralight: Aquamira Drops
If you are on a seriously small budget, and the initial price of a filtration system is setting you back, the cheapest method would be a chlorine dioxide treatment such as the Aquamira Water Treatment Drops. Fifteen dollars gets you two single ounce bottles of drops and treats 30 gallons. We almost gave this treatment system the Best Buy award, but decided that it is such an effective system overall, and so lightweight, that it moves up the ladder and gets our Top Pick for Ultralight oriented users. This system is small, extremely light, and can treat a large or small amount of water. It eliminates viruses and also has the added benefit of killing Cryptosporidium if you wait for an hour, which iodine, the other leading chemical treatment, does not. Aquamira is the top choice among ultra-light backpackers and long distance hikers, and only narrowly missed our winning our Editors' Choice Award because of our preference for not drinking added chemicals when possible.

Top Pick Award for Best Pump Filter: MSR Sweetwater
We decided to give a second Top Pick Award to our top performing pump filter, since filters can treat unlimited quantities of water as well as extract water from small and hard to reach sources. Other high performing methods like the GravityWorks, are not quite as versatile in their water collection capabilities. Even when using Aquamira, if the source is small and silty, getting the water into your bottle may be a challenge. The MSR Sweetwater Microfilter pulled ahead in areas such as ease of use, weight, and simple maintenance. Overall we felt that the Sweetwater was a high performing pump filter for the price, and because it is fairly light, it is still likely that hikers would carry it into the backcountry with them. If you look at our figures below, it averages out to almost the same cost per liter treated as the economical Aquamira drops.

Best Buy Award: Sawyer Squeeze
As the least expensive filter at the outset, the Sawyer Squeeze Water Filter is an attractive option for hikers on a budget. Upon a closer look, it turns out the Sawyer is also the most economical method in the long run. Since it is a simple filter with no moving parts, it is likely to last a long time without breaking, and the company claims that the hollow fiber filter can last for a million gallons, which is considerably longer than any other filter. The Squeeze is an appealing method because it is a very compact and lightweight system and you can immediately drink through the filter, eliminating treatment time. The primary downside to this budget friendly filter is that is does not treat large quantities of water well.

For comparison's sake, we did the math for you for the most cost effective methods:

• The Sawyer Squeeze, treating an estimated million gallons, costs far less per liter than any other option, a mere 0.002 cents per liter.

• The Katadyn Pocket, though by far the most expensive at the outset costing $370, treats 13,000 gallons, which averages to 0.7 cents per liter.

• The Miniworks treats 2000 liters, so it only costs about 4 cents per liter pumped.

• The Platypus GravityWorks, which has a filter life of 1500 liters, averages out to a cost of 7 cents per liter.

• The Sweetwater, treating 750 liters, costs around 12 cents per liter pumped.

• The Aquamira Water Treatment Drops, which treat 30 gallons per package, end up costing around 13 cents per liter.

• Katadyn Micropur Purification tablets, though cheapest at the outset, costs about 43 cents per liter to purify.