Behind the Guardian Purifier’s Technology & Design

MSR engineers designed the Guardian purifier to be the safest and easiest way to purify water virtually anywhere on earth. Achieving such a high degree of performance required advancements in technologies and a great deal of engineering ingenuity.

After six years of R&D, with expertise provided by our in-house water research lab, the result became the world’s most advanced backcountry water treatment device. The Guardian purifier is able to transform even very challenging water sources into reliable, microbiologically safe drinking water. Here’s a look at the features and technologies built into this device.

Testing MSR Guardian Purifiers in the water lab
Ultimate Protection Made Simple

As a water purifier, the Guardian offers greater protection than a microfilter, removing not just waterborne bacteria and protozoa, but the tiniest class of waterborne pathogens: viruses. Traditionally, eliminating the threat of viruses meant treating your water with chemical tablets or UV light only after filtering it first to remove any sediment or dirt. The Guardian eliminates this time-consuming hassle by removing all three classes of these waterborne pathogens–and all other dissolved and suspended solids–in one easy step.

For backcountry and international travelers alike, the advantage is unmatched efficiency, convenience and confidence, especially when you just don’t know what types of water you’ll encounter.

MSR Guardian Self Cleaning

How Does It Work?

The Guardian purifier uses the latest in hollow fiber technology. MSR engineers chose this filter media because it is very reliable in real-world water conditions and incredibly efficient.

Each “fiber” (there are hundreds) is like a straw, with the filter media being the wall.  As water flows through each fiber’s outer wall, their microscopic pores physically trap the microbes and dirt, allowing only purified water through to the hollow core of the “straw”, where clean water flow out towards your water bottle. This physical removal is absolute, meaning you aren’t left wondering whether all the microbes have been sufficiently zapped, which is always the case with chemicals and UV light treatments.

While conventional hollow fibers used in many microfilters today don’t remove viruses (their pore sizes are not small enough to block them), the Guardian’s hollow fibers reliably block viruses, and do so even in very challenging water conditions such as highly turbid or silty water, where other treatment options become less reliable.

Adapted from kidney dialysis technology, it took MSR’s scientists more than two years, working with a U.S. medical-grade facility, to design fibers capable of consistently removing viruses, while still offering a fast flow rate, in a compact, pump design.

In addition, unlike any others on the market, the Guardian’s hollow fibers are not damaged by freezing. Once completely thawed, the purifier is ready to go again. This means you can enjoy sub-freezing nights in the backcountry, confident that your purifier will make it through.

World’s Only Self-Cleaning Backcountry Pump

The Guardian is the only self-cleaning backcountry water treatment pump available. Those familiar with pump or gravity filters know how exciting this is—it eliminates the need to ever backflush or scrub the filter cartridge in the field to regain flow rates.

On every stroke, the purifier uses 10% of its water to clean the contaminants from its filter and flush them back into the source. This patent-pending design not only makes the Guardian purifier hassle-free, but allows it to offer fast flow rates in conditions that would typically clog a filter quickly, such as silty or muddy water.

hollow fiber pump water filter

Just How Fast Is It?

At 2.5L per minute, it’s the second fastest backcountry treatment pump, behind the MSR HyperFlow microfilter, and by far the fastest mechanical purifier available. This means you can fill a Nalgene® bottle in about 25 seconds. In just 60 seconds, you’ll have two filled and be on your way.

10,000+ Liters: A Decade’s Worth of Clean Water

Thanks in part to its self-cleaning design, the Guardian purifier’s filter can last an extremely long time. It can treat up to 10,000-plus liters before the cartridge needs to be replaced (depending on water qualities, of course). To understand how much water that is, consider this: A group that treats 16 liters of water per day, 60 days a year—for 10 years—will only require about 9,600 liters of water.

testing msr guardian purifier in the lab and the field

Rugged Durability for Demanding Environments

The Guardian purifier was originally designed to protect U.S. military troops from waterborne diseases in harsh environments. As such, it’s designed to military specifications. In addition to withstanding freezing, its housing is extremely durable. To ensure it, the MSR water lab team put the purifier through the wringer, including a drop test from 6 ft. to concrete. Needless to say, it’s built tough to handle the rigors of expedition travel, planes, trains, buses and even the occasional burro.

The Only Treatment Device You May Need

With its ultimate protection, speed and ease-of-use, the Guardian purifier may be the only water treatment device you’ll ever need—whether you’re stocking your emergency kit, pursuing an expedition abroad, or simply revisiting your favorite backcountry adventure zone.

Note that despite all of the amazing things it does, the Guardian purifier does not remove chemicals or toxins. Go HERE to learn more about what makes treated backcountry water considered safe (and unsafe) to drink and what your options are for treating it.

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Updated. Originally Published June 7, 2017.

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