MSR Guardian Gravity Purifier

The MSR Guardian Gravity Purifier is certified to NSF Protocol P248, which means it is tested and proven to remove viruses, bacteria, and protozoa from the most challenging water sources.

The system features a built-in backwashing mechanism that clears the filter with every use. This prevents sediment buildup and keeps the flow rate consistent without requiring you to manually disassemble or scrub the filter in the field.

While it is designed with a 10-liter capacity for group expeditions, it is also a great choice for solo hikers who prefer a 'set it and forget it' approach to water filtration. However, keep in mind that the system weighs 18.7 ounces, which may be heavier than what ultralight solo backpackers prefer.

The filter is rated for a lifespan of 3,000 liters. Depending on how often you are in the backcountry and the quality of the water you are filtering, this should last most users several seasons of heavy use.

Yes, the 0.02-micron hollow fiber technology is designed to handle sediment, though extremely silty water will naturally clog any filter faster. The self-cleaning backwash feature helps manage this, but you should always try to source the clearest water possible to extend the life of your cartridge.

Like most hollow fiber filters, the MSR Guardian can be damaged if the water inside the cartridge freezes and expands. If you are camping in freezing temperatures, you must keep the filter element insulated or inside your sleeping bag at night to prevent the fibers from cracking.