OKay, now I have it. I hadn't considered the weight and mass of water, that makes perfect sense. Water is a quite heavy and dense substance that we often take for granted!
I hadn't considered the effect it would have on an empty plastic tank, but it makes sense that after all the air is driven out that as the tank comes back to rest, water would also flush out.
I am sure my overflow comes out the top of the fresh tank, it's just odd that it's routed on a hose down next to the drain. All the fresh fills have that port next to the main hole for the overflow and mine is caulked over. Probably less chance of coming loose and causing a warranty claim.
My rig is a Cruise Lite 262BHXL from Forest River. Hoping not to start another chain/rant/flame, you can tell the amount of TIME they spend trying to make things not break through the warranty period, but not long term maintainable. That said, I mean who cares because that's the world we live in and part of the fun of owning one of these things is all the little fix ups you can do make it work better!
