When I first saw the MSR Guardian and its $ 350, I thought it must be an April Fool’s joke. When it comes to backpacking gear, there's a long list of things I would want to spend that much money on before a water filter.
It was serendipity that several months later I came across a used MSR Guardian filter at an REI Garage sale for $ 20. The reason for return? It filtered water too quickly. I assume the previous user didn’t trust the purifying function of the fast filter rate.
Fast forward several years and countless backcountry trips later, and I don’t have any other piece of gear I love or trust more than the Guardian. It’s been with me through several Boundary Waters trips in northern Minnesota, a canoe trip down the ever silty Green River in Utah, travels through small French towns, a backpacking trip in Iceland, and even road trips across the U.S. I’ve sworn over and over again that I would pay full price for this filter in a second.
But why is it so expensive? There are several reasons, but my favorite is the insanely fast filter time— it can filter a full Nalgene in under 30 seconds. Other filters I’ve used take three times as long. MSR spent six years designing this water filter for the military and it was meant to be used when under fire. This translates into an incredibly smooth and swift filtering experience.
The Guardian also has an integrated backflush function, in other words it cleans itself as you pump, meaning you never have to worry about the filter getting clogged. With every pump, the purifier uses 10 percent of the clean water to flush the contaminants back the way they came. In my years of heavy use, I’ve never noticed a slow in water flow or felt the need to clean out the filter, other than the regular yearly maintenance.
The last reason—and arguably the most important—is the actual purifier pore micron size. The purifier pushes water through an advanced hollow fiber .02 micron filter. Such a fine filter allows the Guardian to safely remove more viruses, bacteria, protozoa, and particulates, than any other filter on the market. Most filters won't catch viruses which is especially a problem if you travel overseas. This is where the MSR Guardian shines through.
In short, if you spend a decent amount of time in the backcountry, I would highly recommend investing in this water purifier. With a lifespan of over 10,000 liters, it’s easy to justify the price. If you drink three-liters a day, this purifier would last you over nine years.