How to Operate an RV Toilet That's Hooked Up to a Septic


Allow waste in the black water tank, which contains waste from the toilet, to accumulate until the tank is about two thirds full. According to RV Basics, adding water to the black water tank allows the RV owner to reach this level whenever they want to drain the black water tank.


Attach the drain outlet of the RV to the septic system. Most RVs have a flexible hose storage area in the back bumper. This hose connects to the outlet of the RV and into the septic system opening. Open the valve for the gray water, the storage tank for waste water from the sink and shower, and allow it to remain open while connected to the septic system.


Drain the black water tank by opening its control valve near the gray water valve. Allow the black water to drain, and flush the tank and hose by running water through the toilet.


Close the black water valve. Run enough water into the black water storage tank to cover the bottom of the tank and add RV sewage tank chemical to the tank.

Tips and Warnings

  • Accomplish additional rinsing action of the black water tank and disposal hose with a rinsing hose or wand. These sink attachments increase the amount of water run into the black water tank and increases the efficiency of the rinsing or cleaning process.
  • RVs with a single waste water tank, a combination of the gray and black water tanks, should follow the recommendations for the black water tank when hooked to a septic system.
  • Campers often connect recreational vehicles parked at a full-service campground to sewer or septic systems. This connection allows direct disposal of waste accumulated in holding tanks to the septic system. However, the amount of water associated with the normal flush of an RV toilet does not clear the waste from the tank and hoses unless special procedures are followed.