Close the valve on your gray water tank the day before you break camp. The gray water tank holds your sink and bath water, which can be used to do the preliminary flushing of your black water tank.
Locate the nearest septic dump station.
Attach the drain hose onto your RV, and then place the drain hose into the septic drain of the dump station.
Open the black water tank valve allowing it to empty into the septic drain.
Run a hose or bucket of water into the RV, and spray the water down into the black water tank to further clean out any waste stuck to the inside of the tank.
Close the black water tank valve.
Open the gray water tank valve to flush the hose, then spray a bit more clean water down the gray water tank to finish flushing the hose.
Close the gray water tank valve.
Remove the hose, and put it back where you store it in your RV.
Wash your hands thoroughly with soap and water after finishing the task.
