Please read your manual. I used to work in a gear shop, and every last one of these we sold was to someone who didn't need it, or needed it because they mistreated their old filter.

Step 1: Don't need a new filter: I've had a MiniWorks for 11 years, if you let it dry out after trips (prevent mold), don't let it freeze with water in it, and make an attempt to get clear water into it, it'll last a decade or more.

Once you think you need to get a new one of these, check the MSR manual (online too!), and scrub off the surface according to their directions. Presto, I probably just saved you $40. Scrub it off, and when you do that, just bite the bullet and get new O-rings for it (normally less than $5 at your local MSR rep).

Also, make sure that you've got the prefilter on the little floatie. That'll again extend the life considerably.

The filter in the unit clogs fairly easily in silty water. It is also fairly easy to clean with the green scrub pad and works well when clean.

Bought a replacement after the original filter in the unit broke when I dropped it a couple feet onto a rock. Wish the ceramic filter was a little more durable it would be nice if replacements were cheaper. Thus the 3 stars...

That said, I am still overall very happy with the MSR Miniworks filtering speed and how easy it is to use and maintain. That was my first problem with it after years of good use.

The filter lasts a long time!!! Easy to maintain and clean!!! Loved it on all the trips!!!

The only reason why I gave this three stars is because the price sucks. Other than that this filter beats all other filters that I have owned. It is extremely fast and makes some super clean (and tasty!) water. Sometimes I have to clean the filter after every single 32 oz bottle that I fill but cleaning it is so easy that I don't even consider this a negative towards msr.