Military-grade water purifier for wild adventures Most water purifiers make you choose – fast flow rates but questionable virus protection, or thorough purification that takes ages and clogs constantly. The Guardian Purifier refuses that compromise. Originally engineered to meet military standards, it’s the ideal companion for anyone travelling where water quality is highly questionable. The hollow fibre filter physically removes viruses, bacteria, protozoa, and sediment at 2.5 litres per minute. Best of all, it’s also self-cleaning: every pump stroke pushes clean water forward whilst backflushing contaminants out, so flow rate stays consistent throughout the cartridge's 10,000+ litre life. No scrubbing filters, no backflushing faff, no watching performance gradually trickle away to nothing. Works with water bottles and hydration bladders, and takes care of even the "worst-case" water sources – the brown, silty, definitely-wouldn't-drink-that-looking stuff. FEATURES SPECS FEATURE VIDEO THE BRAND Meets NSF protocol P248 military testing standard for virus, bacteria, protozoa removal Pumps 2.5 litres per minute for rapid water treatment Self-cleaning on every stroke maintains consistent flow throughout 10,000+ litre life Advanced hollow fibre filter physically removes contaminants to 0.02 microns Military-grade durability withstands freezing, drops, and harsh environments Works with water bottles, hydration systems, and cooking pots No backflushing or filter-scrubbing maintenance required Weight 490 g Dimensions 21 × 11 cm Effective Against Bacteria Yes Effective Against Chemicals/Toxins No Effective Against Particulate Yes Effective Against Protozoa Yes Effective Against Viruses Yes Filter Media Advanced Hollow Fiber Filter Pore Size 0.02 microns Flow Rate 2.5 L/min Cartridge Life 10,000+ L Field Cleanable Self-cleaning Field Maintainable Yes Water Bottle Adapter Yes Cartridge Replacement Indicator Yes A staple of multiple expeditions for more than 50 years, MSR gear is trusted by climbers, mountaineers, explorers and researchers in some of the highest and coldest places on earth. The brand has earned an enviable reputation for turning out reliable, durable, high-performance kit – and has come a long way since its founding by Seattle engineer and lifelong mountaineer Larry Penberthy in 1969. Back then, MSR – or Mountain Safety Research, to use its full moniker – was solely focused on improving the safety of climbing equipment. Why? Because Larry knew that better equipment meant greater adventures. Since then, the product range has grown hugely, but the core ethos remains the same. That’s why MSR gear is characterised by its user-led design that prioritises functionality, simplicity and reliability, wherever you roam in the great outdoors – whether you’re on a weekend camping trip, or perched on a portaledge 2,000ft up one of the world’s big walls.
