You don't. :M Once a few years ago we were at Lake George RV Park right at the end of the season and anxious staff had closed the dump station for the year. No worries, I took my full grey water Aquatainers in the back of the vehicle over to the nearest bath house which coincidentally was located on a hillside. The actual bathrooms were down a flight of stairs on the lower floor so I can't say I enjoyed carrying 60 lbs of full Aquatainers down the stairs and disposing of the contents in the toilet but at least I had the choice ... with a wheeled tote tank I don't know what I'd have done as there would have been no other option for disposing of that grey water other than just letting it run out on the ground as I wasn't going to tow 600 km home with a full GW tank.