Where should you dewinterize?

I hook up a hose at home and flush the entire system as well as I can. I DO NOT dump until I get to a CG on the first trip. Your tanks can take the few gallons of "new "water with ease. Even AT the campground, open the gray water tank and flush the lines again until you see clear water from all the spigots.

Then open the black water tank as you need to like on a normal camping trip. However...NEVER dump anything on the ground. Illegal and stupid. Even on your own property.