path1 wrote:
Maybe just me...When dumping after hooking up drain hoses, Pull gray maybe 2 seconds to make sure No leaks (gray spill easier to deal with than black). Close gray. Open black, wait till empty, close black. Open gray, to get most nasty stuff out of drain hose. Close gray. Keeping your drain hose in sewer hole, rinse your drain hose. Water in top and shake your hose around, maybe 30 seconds. Remove drain hose put where you store it. If anybody in line, drive away! If nobody in line and your the type that likes to give your tanks a water massage to get out the last spec of whatever go ahead.
That is basically the way that I do it. I also like to flush out both tanks with fresh water when I get home. The black tanks always gets drained first and the gray tank second.
A lot depends on the way that they are piped. Theoretically, if the black tank had more in it than the gray tank, and the gray and black tanks were opened together, the black tanks contents could end up in the gray tank if the drain hose didn't drain fast enough or had a blockage. That is not a pretty sight. LOL
