Gray tank overflow

[WarrenG]

Like many people, we use a Valterra Waste Valve at the combined outlet of our waste tanks, and I've read about people opening both gray tank valves to equalize the amounts in their gray tanks when one of them might otherwise be full, but yesterday I noticed on our 27.5RLTS that the black drain pipe in the basement for the bathroom sink and shower already have an overflow system in place, i.e. if they fill their tank and water gets up the pipe far enough it will begin flowing into the kitchen sink's gray tank.

Relying on this overflow will eliminate the potential problems one might have when both gray tank valves are open and the Valterra valve is the only valve used to hold back a lot of water. FWIW, I have installed a large worm-drive pipe clamp around the Valterra valve to reduce the chance of it getting twisted off while I'm twisting off its cap