footsloggin' photog wrote a review of MSR MiniWorks Ex Water Filter on July 5, 2009
This is a great filter. There are some reviews that state it slows down in "silty/ muddy" conditions, but there isn't a filter available that doesn't slow down when filtering silty water. The only way to prevent this is to "prefilter" as much as possible with a coffee filter or bandana if the conditions warrant such extra effort, but it is better to avoid very silty water if you can. I have had to filter some pretty muddy water in a pinch, and it does slow down, but, once you're done, the cartridge cleans up fine and you're good to go. With all that said, this pump has been awesome. I have owned one for several years and many people I know have owned theirs for years as well and they are always reliable and have never left me or anyone I know without a steady supply of water, and I have never known any of my backpacking friends to get sick from filtered water from these units. The only reason I wouldn't give it 5 stars is for the weight....not that there is a better option out there. There are a couple of new filters out there such as the hyper flow from MSR, but it hasn't had enough time in the field to prove itself, in my opinion. If you need a good reliable, field maintainable filter, get this one!!