Water Filter Review: MSR Guardian Purifier

MSR Guardian

MSR Guardian Purifier

Must-know info:
* $350
* 24.4 ounces
* Filters up to 10,000 liters
* Filters bacteria, protozoa and viruses
* 0.02 Micron Filter
* Can sustain freezing

The MSR Guardian Purifier filters to 0.02 microns to remove viruses. It can survive drops of six feet and is the only filter in our review that isn’t damaged by freezing. It can pump up to 2.5 liters per minute and uses 10 percent of pumped water to back flush the filter, giving it an estimated lifespan of 10,000 liters. The Guardian has great attention to detail: The clean end of the pump is sealed with a threaded cap the same size as a standard Nalgene or wide-mouth Klean Kanteen, so you can attach your bottle and pump at any angle. Sound too good to be true? The Guardian is by far the most expensive and the heaviest filter we tested. It’s also very bulky compared to the average pump filter. It is unique in meeting rigorous third-party testing: NSF Protocol P248 Military Operations Microbiological Water Purifiers. That’s really the story of the Guardian, trickle down technology from military R&D. If you are truly concerned about contaminated water, this is the only filter on the market we’d suggest with no reservations.

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