If I can, let me add a little to Wayne and Sam. Buy a clear plastic elbow to hook between the drain fitting and the hose. This will show you when clear water is flowing from the tank. After I drain and flush with the water hookup, I close the valve a couple of minutes with water still running then reopen to drain that partial fill (depends on your tank size--mine is 38 gal and two minutes will not even 1/2 fill the tank back up). That floats any paper, etc that might still be clinging to the sides, etc. Finish with the drain open and the flush water running for a few minutes. If you drive a distance before emptying the tank, everything will be liquid and drain/flush clean quickly. If you empty the tank as you leave the park, solids and paper will still be solids and thus will take longer to flush clean. Put your tank deodorizer in toilet, flush down and you are good to store. Like Wayne said, drain gray water last. I've found some people using regular toilet paper. That will for sure stop a macerater type toilet and will sooner or later cause dump valve problems with the drop valve type.