Add a cup of bleach into the the fresh water tank thru the fill hole, run the taps for a while to flush out everything. Let the water sit in there for about an hour then Drain the fresh water tank out. Refill the tank with fresh water and flush out the bleach water in your taps. Repeat the refill and flush out step a couple of more times and you're ready to go. I've done this once when I first picked up the new Hybrid. I'm guessing once a year I should clean mine out. Once in the spring just before we go camping again. Hope this helps