How Does an RV Bathroom Work?

RV bathrooms look and work in a similar way as home bathrooms do. The main difference is that RV bathrooms have their own sewer systems. The shower, sink and toilet in a house bathroom drains into a city sewage system. In a RV, they drain into holding tanks that must be manually emptied by the RV owner.

Water is brought to the sink, shower and toilet of an RV through a hose that is hooked up to the water intake connection located on the outside of the RV. The sink and the shower drain into a holding tank, called a gray water holding tank, that is located underneath the RV. The toilet drains into a separate holding tank, called a black water holding tank, that is also located underneath the RV. The toilet drains into its own holding tank, to keep human waste odors separate from shower and sink water. That way the human waste odors do not come through the sink and shower drains.

The gray water holding tank can be kept open during use if the RV is hooked up to a sewer connection. Some campgrounds have sewer connection hookups for RVs. If the RV is not hooked up to a sewer connection, the gray water tank must be kept closed. When the gray water tank is full, which happens quickly when the shower is used, the RV must be driven to a RV dump station to empty the tank. Once a month a RV holding tank treatment product should be put into the gray water tank to clean the tank and prevent odors. The treatment is put into the tank through the sink.

The black water tank is much trickier to maintain than the gray water tank. A RV holding tank treatment product must always be kept in the black water tank, to mask odors and break down the toilet paper. The holding tank treatment is put into the black water tank by flushing it down the toilet. The black water holding tank should always be kept closed, even if the RV is by a sewer connection. The black water tank should not be emptied until it is 3/4 full. The reason why is, a fuller tank will flow through to the sewer faster, which helps to fully empty the tank.

The black water tank should always be emptied before the gray water tank, that way the gray water will clean out the sewer hoses. To empty the tanks, one end of a sewer hose is hooked up to the sewer connection on the outside of the RV. The other end of the sewer hose is hooked up to the sewer connection at the RV dump station. The valve for the black water tank is opened, allowing the black water, toilet water, to empty through the sewer tube and into the sewer. Once the black water tank is empty, the valve is closed. Then the valve for the gray water tank is opened, allowing the gray water, the sink and shower water, to empty into the sewer. As the gray water empties, it cleans any remaining black water from the sewer tube. Once the gray water tank is empty. the valve is closed. The sewer hose is disconnected and stored in a compartment under the RV for later use.