I know it probably seems like an obvious thing to say but you would be surprised to discover how many people don’t actually wash their belts when they wash their gi’s. I have heard some people say they don’t wash their belt because stripes come off in the wash or that the belt colour fades and it starts looking tatty, which is ironic really, I mean once they get to black belt people want their belts to look well worn and tatty, but I guess a well worn blue belt does nothing more than make you look like you have been at blue belt level for far too long.
Bacteria breeds on a dirty gi and infections such as ringworm and staph are easily transmitted, neither of which you want to catch. But those same bacteria that breed on your gi also breed on a dirty belt, why shouldn’t they? after all it is made from the same material as your gi and equally as inviting to those dirty little bugs.
Your belt should be washed as often as your gi, which should be after every roll. If your stripes come off, tape some more on and if your belt gets worn and tatty, buy a new one. Its really that simple.