Prepare the tank for flushing by adding water softener to the tank through the toilet inside the RV. A mix of 2 cups softener to 1 gallon water will help remove any solids that may stick to the sides of the tank.
Secure the black water tank to the septic dump station, using the flexible sewer hose. Open the valve to allow the contents of the tank to flow into the septic system.
Flush the black water tank by running fresh water through the toilet and into the tank. Keep the dump valve open so the water does not back up inside the RV. Allow the water to run for 3 to 5 minutes. Turn off the fresh water hose and remove it from the toilet. Allow any remaining water in the tank to drain before closing the valve.
Disconnect the flexible sewer hose from the RV and the dump station. Rinse the hose with the fresh water supply and put away for future use.
Add a deodorizer or enzyme product to the toilet, along with the recommended amount of water. This will prepare the emptied tank for the next time you use it.