Holding tanks on an RV carry the waste contents until you can get to a dumping station and get rid of it. While in the tanks, the waste water is processed similarly to the waste in a septic system by using bacteria from our bodies to break down larger waste. However, the tanks are not part of a complete septic system, since the entire contents of both tanks are dumped when they are emptied and no water is left them. Most people will make sure the tanks are empty if the RV isn't going to be used for awhile. However, you may also want to clean out the tanks to prevent smells from developing. It is also a good idea to clean out the tanks periodically while you are on the road.
Remove all waste from the tanks by disposing of it at a dump station. RVs have what are referred to as gray and black water tanks. The black water tank holds bathroom waste, while the gray water tank holds water that comes from sinks and showers.
Add water softener to the tanks by pouring it down the drains. Use 2 cups for each tank.
Add bleach detergent to the commode to get the soap into the black water tank. Flush the commode to allow the soap to get into the black water tank. Leave the detergent in the tank. It will help keep the tank odor down until the next time you empty it. The gray water tank should have soap in it already from the sinks and shower.
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