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How to Store a Water Filter in the Off Season

You can’t use a water filter or water purifier when temperatures dip below freezing without risking the integrity of the filter element. Filters and purifiers can be expensive to replace, so it pays to take a few simple steps before you store them so they’re fully functional and ready to go in the spring. Here’s how.

Backflush Your Water Filter or Purifier

Many backcountry water filters and purifiers can be backflushed, which means reversing the normal flow of water through the filter element. This serves to unclog any debris or contaminants that are stuck in the filter and flush them out. Many filters and purifiers come with a hose (like the Platypus Gravity Works System) or a syringe (like The Sawyer Squeeze) that you can use to perform this backflushing operation.

If you’ve used your water filter or purifier recently, you only need to perform the backflush operation a few times to clean it out. If you haven’t used it recently and the filter element is “dry”, it’s best to run water through the filter in the normal direction to wet it out before commencing the backflushing operation. Whatever you do, don’t exert any extra pressure when you backflush the filter element because it can rip or deform the internal filter element, which may just be paper, depending on the product you use.

Flush With Chlorinated Tap Water

Next, filter a few liters of chlorinated tap water flowing in the normal direction just like you would in the backcountry. Chlorinated city water is sufficiently purified to kill off any bacterial blooms or mold from growing in your filter/purifier when it’s stored away. If you don’t have chlorinated water where you live, make some using the normal concentration of Aqua Mira or Bleach, per the CDC’s directions for making potable chlorinated water using household bleach.

Drying and Storage

Let your filter/purifier dry out slowly and naturally by placing it in a warm and well ventilated location, out of direct sunlight. After a week, move it to a drawer or closet in the heated part of your home. Come spring, it will be ready to use.

That’s all there is to it!

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10 comments

  1. Thanks for the generic info. However, Sawyer, specifically, actually recommend that you DO use extra force when backflushing, to avoid creating a “path of least resistance”.

  2. Make sure you read the manufacturers instructions that comes with the Filter,,some city water due to the chemicals in it may have a negative impact on the filter element and do not add bleach to the water thinking it will increase the cleanliness process…

  3. And when boiling your MSR Microfilter cartridge to sterilize it (as recommended by MSR), don’t walk away and forget about it…

  4. Katadyn Pocket user since 2007. It has worked wonderfully and has a 50,000 liter lifespan per ceramic cartridge. I’m nowhere near that. The cartridge will likely outlive me.

  5. If you use a Steri-Pen instead of a filter, take the batteries out in the off-season. It seems to have significant battery drain just sitting around.

  6. Best Waterproof Tent Guy

    Thank you! I didn’t know that chlorinated tap water is strong enough to kill the bacteria in the water filter. It is a cheap solution, it is going to save me a lot of money.

  7. Hi,
    You are right. In cold winters, we need to protect our water filters, or they will not work in the following spring. You tips are great. Thanks.

  8. Thanks, Philip! I will pay attention to this.

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