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?

1 Answer 1


As I understand the technology, your microfilters will not expire on the shelf if maintained and stored properly. Their lifetime is determined by the number of gallons pumped.

What can happen is if you don't properly dry out your filter before storing then it will develop mold. In that situation you can decide if it is best to clean the filter or replace it. For cleaning instructions I copied the following from Katadyn's Q&A page:

It is very important that the ceramic element be completely dry before it is stored for an extended time period. It is recommended to dry the element for up to 3 days before putting it back in the filter. If the filter has been stored damp and has a foul odor, we recommend the following: Pump 1-2 liters of water, combined with a small amount of Micropur Forte or baking soda, through the filter; then soak the ceramic element in the combination over night. Rinse it out and pump several liters of clean water through the system. For a taste test, use natural, non-chlorinated, water.

  • 2
    I would add that you can buy dye which you can use to test filters. You put the dye in water, pump, and if it comes through the filter... then it's no good. Feb 21, 2013 at 2:12
  • related (detail about what @RussellSteen is talking about) outdoors.stackexchange.com/questions/13489/…
    – JinSnow
    Sep 28, 2020 at 16:20

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.