MSR Guardian Pump Water Filter

The MSR Guardian is a pump-action water purifier that sets a new standard for backcountry water treatment. Originally developed for military use, it provides ultimate protection against waterborne threats, making it ideal for international travel, remote wilderness adventures, or emergency preparedness .

Military-Grade Viral Protection

The Guardian uses advanced hollow fiber technology with a 0.02-micron pore size to physically remove 99.99% of viruses, 99.9999% of bacteria, and 99.9% of protozoa (including Giardia and Cryptosporidium) . It meets the rigorous NSF Protocol P248 standard, the testing protocol used by the U.S. military for purifying "worst-case" water conditions . Unlike most hollow-fiber filters, this medical-grade fiber technology effectively blocks viruses without the need for chemicals, UV bulbs, or batteries .

Fast, Self-Cleaning Operation

The purifier pumps water at a rapid 2.5 liters per minute, allowing you to fill a 1-liter bottle in under a minute with approximately 35 pump strokes . Its innovative self-cleaning design uses 10% of each stroke's water volume to flush contaminants back into the source, maintaining consistently fast flow rates without the need for manual backflushing or scrubbing . The cartridge has an exceptional lifespan of 10,000+ liters before needing replacement .

Built for Extreme Conditions

The Guardian is engineered to withstand heavy use, freezing temperatures, drops from up to 6 feet onto concrete, and harsh environments . It weighs 490g (1 lb 1 oz) and measures 8.2 x 4.7 inches . The unit is compatible with wide-mouth Nalgene bottles and MSR Dromedary bags, and includes a water bottle adapter and cartridge replacement indicator . The purifier is made in the USA and backed by a 3-year limited warranty .

Important Considerations

While the Guardian is highly effective, it does not remove chemicals or toxins . The pump requires annual maintenance, including replacement of O-rings and piston seals, especially if stored for extended periods . Some users have reported leaks around the base or the need to adjust the tightness of connections .

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