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MSR Guardian Purifier – Last One You’ll Ever Need

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[leadin]We’re sitting in rafts, floating on the opaque Bella Coola River in British Columbia. In its tiny airport, the town of Bella Coola sports signs warning people to drink bottled water, and looking at the cloudy green river, it’s easy to see why.[/leadin]


That murky, non-potable water is why we’re spending a week in Bella Coola (besides the glaciers, granite peaks, and wildlife, of course). We’ve been flown out to test gear and try the new Guardian Water Purifier, a beefy, top-tier model by MSR.

Photo by Scott Rinckenberger

The company claims the Guardian clears out ALL biological nasties, including viruses, so there’s no need to bring along a UV purifier or chemical tablets when traveling abroad. The only drawback might be the price. At $349 this is among the most costly pumps ever put into the outdoors marketplace.

‘Medical Grade’ Filter

By using a medical-grade hollow fiber filter with smaller pores than traditional hollow fiber filters, the Guardian physically removes viruses, bacteria, protozoa, and particulates from water. It might not taste better, but at least you won’t get sick.MSR Guardian

Against The Competition

The Guardian is not the only .02 micron filter on the market. Sawyer also makes a .02 micron filter that is fed by gravity, and it’s much less expensive at $140.

The Sawyer Complete 4-Liter Dual Bag Water Purifier System provides the same level of filtration as the Guardian. Filtering one bag to the other through a gravity-fed system, it also removes bacteria, viruses and protozoa.

Why choose the more expensive pump over the gravity system from Sawyer? Besides the fact that the Guardian is self-cleaning, it takes the Sawyer 15 minutes to purify 2.5 liters of water, but it only takes the Guardian 60 seconds. Whether or not that’s worth the additional money will ultimately be up to the consumer, but that’s a huge difference when you’re swatting mosquitoes by a stream while replenishing your water supply.


Self-Cleaning Filter

The Guardian’s ability to self-clean is my favorite part of this new filter, and to me it is worth the extra cash for something that will last for 10 years or more.

The filter cleans itself with a second line that back-flushes water as you pump, so you never have to back-flush or scrub the filter manually. It also doesn’t require you to pre-filter water. No maintenance is my kind of maintenance.

At $350 it’s not cheap, but its status as a one-filter-cleans-all purifier coupled with an extraordinary filter life and durability (see below) means it could be the only one you’ll have to buy.


MSR says the filter is crush tested to 300 pounds and won’t break if it’s frozen. It can withstand a six foot drop test.

msr guardian testing

First Person Testing

We dropped the filter’s intake hose into the murky “this-was-ice-yesterday” water, and I braced myself for a week of intestinal distress.

Pumping the filter was smooth and easy, with little resistance (it was comparable to the Miniworks EX model), and the stuff filling up my water bottle was crystal clear. The filter moves plenty of water at 2.5 liters per minute, and my water bottle filled in well under a minute of pumping.

Of course, you can’t see all the little bugs in water that can wreak havoc on your system, but shoot, I’m a journalist; I’ll take one for the team.

The filtered water was cool and refreshing, and since it’s been a week and I haven’t had diarrhea yet, it looks like I’m in the clear (whew).


  • Price: $349
  • Weight: 1lb., 1oz.
  • Filters Out: Norovirus, rotavirus, hepatitis A, E. coli, shigella, salmonella, cholera, giardia, cryptosporidium, amoebae, and more.
  • Speed: 2.5L per minute
  • Capacity: 10,000+ liters before filter change


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