Extend cartridge life and preserve flow rate by drawing from the clearest possible water sources: calm pools, rocky streams, and headwaters. Avoid algae-filled ponds and turbulent, silty streams.
If you must filter dirty water, prevent clogging the prefilter and cartridge by wrapping a coffee filter or bandana around the prefilter with a rubber band.
Never allow water to freeze inside the filter, as ice can rupture fragile cartridge components. Pump all water from the cartridge before packing it away.
Ceramic or silica depth filter: When you notice diminished output, remove the cartridge from the filter housing (take care not to drop it–ceramic cracks easily) and scrub the outer layer with a cleaning pad (generally included; use fine steel wool or sandpaper if not).
Pleated filter (or filter cover): Remove from the housing and swish it around in clear water to rinse away surface sediment.
Hollow-fiber filter: Backflush after each trip by reversing the direction of water flow. Unscrew the inlet cap, flip over the check valves, and pump a half-liter of filtered water through the cartridge to clean it (see product manual for complete instructions).
Disinfect all filters at the start and end of each season by pumping one capful of bleach mixed with one liter of water through the cartridge (use just a few drops of bleach for hollow-fiber models). Disassemble the filter and let all components dry completely.
Pump not drawing water? Try turning the housing upside down and pumping again; that often gets it going.
No luck? The problem is probably dry, cracked, or dirty O-rings. In the field: Remove O-ring from the piston, clean with a soft cloth, and lube with silicone grease, lip balm, or saliva. At home: Replace damaged or worn O-rings.