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  • Removes 25 micron particles before they reach the main filter
  • SiltStopper is more porous than a SweetWater filter and may clog sooner—prefilter replacements sold separately
  • Attach the MSR SweetWater SiltStopper such that the red side filters the incoming water

Made in USA.

View all MSR Water Filter Accessories

REI membership


Best Use Backpacking
Rated 4 out of 5 by from It Works Prolongs the life and maintenance intervals of your main filter. When it clogs up, you can back-flow it by installing it on the pump output, and that usually works. Otherwise, in a pinch, you can peel the outer layer off like toilet paper to reveal a clean surface. It does make pumping a bit more work, especially to get the pump primed initially. A filter insert lasts several hundred liters under normal use. To the guy who tried to use it in Denali in glacial silt, I have to laugh. NOTHING will last filtering glacial silt. That's death for any water filter. Always look for the clearest water possible. If you must filter the glacial silt, allow it to settle for an hour or two in a bottle or bucket, then filter it.
Date published: 2011-06-08
Rated 5 out of 5 by from SiltStopper Works I used the SiltStopper on my thru-hike of the Pacific Crest Trail. I went through a total of four pre-filters over about 2000 miles. Each pre-filter would last about 500 miles and I filtered all of my water. For the first 500 miles I didn't use a pre-filter and my Katadyn filter became difficult to pump and required replacement. After using the prefilter my Katadyn filter lasted over three times as long, over 1500 miles. I recommend back flushing the SiltStopper filter prior to the pre-filter clogging. When that doesn't work simply replace the prefilter cartridge. In summary the SiltStopper works.
Date published: 2010-10-05
Rated 5 out of 5 by from Must-have accessory for the Sweetwater Since even the clearest lakes can have an alarming amount of particulate matter, this really extends the life of your Sweetwater pump filter. Plus, you will not have to clean your ceramic filter as much in the backcountry. I have even found that I can 'clean' the paper filter a couple of times before I replace it with a new filter tube. While the filter paper is wet, I gently rub the outer layer of paper off. This discards the clogged outer shell and exposes a fresh surface. It is perfectly safe since this is only the pre-filter.
Date published: 2008-02-13
Rated 4 out of 5 by from Great insurance I bought the prefilter when I purchased my SweetWater. Even in clear water the prefilter catches a lot of silt. I've used this for over a year now and it is very brown on one side and the other side it still white. The main filter in my SweetWater still looks like new. The replacement filter come on a nice case so you can bring extras if you know you are going to be filtering some dirty water. It's a great way to extend the life of your main filter element.
Date published: 2014-12-28
Rated 2 out of 5 by from Doesn't work on silty water, not worth the money! I tried to clean in the field because it clogged very quickly in silty water, I was able to wash it off gently twice and then the paper filter broke. Great product otherwise but, if the water is clear you really don't need it if you have the ceramic filter cartridge. The cost of the pre-filter is high and the cost of the replacement paper filters is stupid! they should only be about $9.95 for three. you can buy the entire unit for 19.95 thats too high $9.95 would be ok but not worth the money! They should be cleanable in the field without breaking. Design is good but the design of the filter needs improvement, maybe use a technique like K&N air filters and use a wire mesh and gauze to justify the price. Easier to clean the regular filter housing.
Date published: 2014-08-27
Rated 5 out of 5 by from a must-have . . . Regardless of what type of water filter you have, the Siltstopper is a very useful add-on. As the name implies, this thing stops silt from getting to the more expensive filter, thus prolonging the life of your filtration system. The replacement filters come in a 3-pack and usually go for about $20.
Date published: 2015-05-05
Rated 3 out of 5 by from works, but split during cleaning I just bought this as a pre-filter to my sweetwater that is over 20 years old. It definitely catches algae as the outer part quickly turned an olive green while the inner part remained white. It has a small surface area so it clogs rather quickly, but I suggest that you just buy extra filters rather than trying to clean it. When mine clogged the pump could still provide enough suction to evaporate (boil) the water through the silt stopper, but it was a very slow process to filter water. When clogged it took over 15 minutes to fill a Nalgene that normal took less than 3 minutes. The instructions say to connect the silt stopper in reverse on the filter output to clean it, but that just caused the silt stopper cartridge to split in half making it worthless. Anyway now that I own the housing, I’ll just make sure to buy enough cartridges so I won’t have to bother cleaning them.
Date published: 2007-09-12
Rated 4 out of 5 by from great to save your filter Great to save your main filter. You can reverse the filter inlet & outlet and discharge to quickly field clean the filter. Abuse this little guy and save your more expensive main filter!
Date published: 2007-11-27
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Is this compatible with the miniworks filter?

Asked by: Tim the Enchanter
This product is designed for use with the MSR SweetWater Filter. We have not tested any other filters with this product.
Answered by: REIservice
Date published: 2015-09-20

Nowhere on the packaging is the direction of water flow indicated. Which side of the siltfilter is the input for dirty water and which side outputs cleaner water?

Asked by: danaeliza
​The long tube on the end takes in the dirty water and the plastic part on the filter connects to your filter.
Answered by: REIservice
Date published: 2017-05-26

How much does it weigh?

Asked by: Section Pistols
The SweetWater SiltStopper Prefilter weighs .9 ounces (26 grams).
Answered by: REIservice
Date published: 2015-09-20

What is the size of the inlet and outlet ports? The ID (inner Diameter) and the OD (outer Diamenter)? Can it be used with 1/4" ID tubing?

Asked by: charliez
The SweetWater Siltstopper is designed to be used with the SweetWater hose – it has an inner diameter of 3/16".
Answered by: REIservice
Date published: 2015-09-20
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