Immediately after making a batch, I wash the bag thoroughly with dish soap and water, then air dry it on one of those plastic bag dryer stands. I use a little milk, so it is particularly important to clean it right away. The bag gets discolored pretty quickly, but they don't smell badly and seem to last forever. Normally, I only change the bag because it feels like I should. It is inevitable that the fabric will degrade, but I haven't noticed any diminished taste or performance with my usual strainer bags. Wakacon has been my bag of choice for a while now, but I sometimes use the Kavafied pro bag, too. Occasional boiling sounds like a good idea.