Use gray to flush black

BarneyS wrote:

Vintage465 wrote:
Before I got a trailer with a Sani-flush, I would drain the black tank first...leave the black tank valve open....Then......Carefully remove the end of the hose from the dump station hole and hold the hose up in the air, higher then the tank and reach down and open the grey valve. The grey water would run into the black tank 'til it equalized...tricky part was shutting both valves while you continue to hold the hose up. And there would be a little "mixed" waste water in the hose while you got it back to the dump station hole. I suppose you could install a third valve to manage that though.

Just get a Valterra Twist On Gate Valve and put it on the end of the drain pipe just in front of the slinky. That way, you can close the valve, open both grey and black valves, and the liquid will equalize without going down the slinky. When done, close one of the tank valves, open the Valterra and drain as usual.

It looks similar to this one but without the clear plastic elbow.
Barney

I always thought to myself why don’t they plumb the gray tanks to flush through the black tank to help clean it out. Then a while back I bought the twist on valve. OMG it works like a champ! I still use the sani-flush to keep clear water flowing into the black, but this is the way to go.