I have a PUR Hiker Microfilter and a Katadyn Water Microfilter sitting in my closet that I only use once in a great while (I don't go on overnight backpacking trips very often).
Whenever I do plan on a trip, I'm always hesitant to trust these filters are still in good condition to use. Don't they develop mold or other contaminants when left idle for years? I'm talking like 5 or so years without use...
Is there a way to clean these so I can be sure they are safe to use, or does the microfilter cartridge have a certain shelf-life and is then no longer safe to use?