For Those That Sit: If you end up with an Odor after sitting a long time. The bacterial brigade likes oxygen and after sitting still in the same spot for some time there isn’t enough shaking going on to keep the oxygen distributed though the holding tanks. Result: the bacterial fellows are unhappy, leaving the job half done. It helps to flush more often. Solution if this happens: Fill up the tank, then dump it. Now nearly fill the tank, add at least a half cup of baking soda, and let the whole thing percolate for a couple of days, dump the tank and add Happy Campers per instructions.