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MSR SweetWater Prefilter

rated 3.0 of 5 stars
photo: MSR SweetWater Prefilter hydration accessory

Works fine for a while, but the manual and product support from MRS is lacking because they don't bother to tell you how to identify the difference between a clogged prefilter and a clogged ceramic filter. I, and I'm sure many others, have needlessly bought replacement ceramic filters when it was the prefilter that was clogged.


  • Easy to replace
  • Keeps the ceramic filter clean a long, long time
  • With experience, it is easy to feel the difference between a clogged prefilter and a clogged ceramic filter
  • You can use the hose to blow into it to "back-flush" it with limited success


  • You can not see when it clogs because it clogs inside
  • No way to pop it open to see any clogged material

MSR was good to send me a replacement, but what they have not told me is what solution(s) to best clean it with. When you try to pump water and there is an obvious blockage in the "suction" feel on the handle instead of blockage on the "push" stroke, with no water popping out the relief valve, you have a clogged prefilter.

Right now I am in the process of trying soaking it in vinegar (so far has not helped yet) then I will try a detergent soak and then a diluted Chlorox soak. This is the 2nd time I have done this cleaning. The first time it got my old prefilter working OK.

Now the old one is still working but the replacement is about stopped up. Maybe at least I will remember which solutions actually helps it. You can tell how clogged it is by blowing through the hose into the filter sitting in water or any solution, and comparing how hard you have to blow.  

I have hiked almost 800 miles of the AT so far with this filter system. It took me half this distance to figure out exactly what the problems were. 

Source: received it as a sample, freebie, or prize (MSR after the original one clogged)

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Price MSRP: $9.95
Historic Range: $0.99-$9.95
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