Yup,. I have 3 waste tanks. Black, Gray and Wash (Rear shower and lavs).
Rules depend on the tank
Places I know of where you can legally dumnp Black tank on ground: NONE
Places where you can legally dumnp GRAY.. Well quite a few but still "Few"
Places where you can dump WASH on the ground legally.. Many
NOTE: Many does not equal EVERYWHERE.
Difference between Wash and GRY... Kitchen sink (food particles).
I use a 3/4" Gray hose for the shower/rear basins, and 3" for the other stuff, Adapters at the sewer inlet (hole in ground)handle the mix.