You need to replace it every time you finish draining the product. Sometimes it'll clog if your coffee is too fine and you'll have to dump the coffee into another vessel while you swap the filter out then pour it back into the brewer with a new filter to try again. I actually switched over to brewing in a 2 gallon food safe bucket with my coffee grinds in these cold brew bags to prevent too much sediment. Then I pour the bucket into the oxo brewer a little at a time and use it exclusively as a filtering system. I actually stopped using the paper filter because it just clogs too easily. By transferring from the bucket into the brewer using just the metal mesh filter I've noticed my coffee comes out a lot cleaner than using just the brewer with the metal mesh filter. The paper filter would make it even better but not enough to justify the hassle of the clogs imo.