the best Water Purifier…           MSR | Guardian

Why it’s the best:

Capability: MSR Guardian filters water sources no other purifier (or filter) can.

Speed: It filters fast (0.66 gallons per minute) and is low-effort to pump.

Maintenance: Self-cleaning with every stroke.

Durability:  Tested to survive freezing, hard drops (6ft to concrete!), and harsh conditions.

Longevity: Purifies 2641+ gallons of water before needing filter replacement.

Effectiveness: This is a “purifier” (i.e., removes viruses, bacteria, and protozoans). This makes it effective worldwide, for the worst sources (whereas a “filter” leaves you susceptible to viruses/bacteria/protozoans).

Other great features:

Outlet cover: The water outlet has a screw-on cover to prevent contamination in the bag.

Threaded: The water outlet is threaded to fit Nalgene and wide-mouth Kleen Kanteen bottles (and equivalent). This lets you purify standing up.

Carry bag: The carry bag is made of heavy-duty fabric for longevity, including durable mesh for evaporation.

Field-testable: Easy to verify filter is functioning properly in the field with a transparent bottle. 

Nothing’s perfect:

Weight: At 17 ounces, it’s not the lightest filter/purifier. But what’s a few extra ounces for something that works – where nothing else does.

Cost: It ain’t cheap. But buy once, cry once. Your life and health are worth it.

Handle: On release, there were a few instances of handles breaking. MSR quickly reinforced the handle. Nonetheless, you could still break it if you tried. If it’s suddenly hard to pump, look for an obstruction (e.g., the bottle you screwed on to is full).  Don’t try to brute-force it.

Tales from the field:

On a Utah trip, the only water source for miles was a small puddle in the sand of a barren canyon. Decomposed sandstone has the finest silt, combining the worst features of sand (abrasive) and mud (caking).  Walking within five feet of the solitary puddle stirred it into a cloudy brown mess of silt (which took 10 minutes to partially settle).

In went the pump, stirring up more silt. The first few pumps primed it. Then, slowly, I kept pumping, and it kept working. The backflush port spewed out thick brown water full of concentrated sand. I could see the sand, silt, and mud in the pump body. But lo and behold, it worked! It purified liter-after-liter.

That was the sole water source for three days. Day after day, the pump kept pumping, with perfectly pure water emerging. No clogs, no failure, no servicing, no maintenance. No other filter or purifier on the market would have stood a chance.