Park the RV on a flat and level surface. Turn the holding tank's sensors on and check the fill level. Your RV's sensors may be located in the rear of the rig on a panel system. If unsure of the panel's location, consult your RV's owner manual. If the tanks are full, drain them into the appropriate dumping facility, typically found at campgrounds or sanitation stops in truck stops.
Put on the rubber gloves and fill the bucket two-thirds full with warm water and add two caps of the bleach into the water.
Go to the sinks and shower drains in the RV. Pry the drain guards off the sink and shower floor and scrub the area with the bleach and water. Pour some excess bleach water down into the drains.
Wash the drain guards thoroughly in the bleach water solution. The bleach kills the odor-causing bacteria while also cleaning the overflow areas off the holding tank. After draining the holding tank, pour the remaining bleach water down the drain. The bleach will rest in the holding tank, killing bacteria that leads to odors in the overflow areas.
