[jawsmon]

I agree with flybouy, I have yet to see an RV that has only one valve for the black and gray tanks. A valve handle must be missing.

I had a similar problem, I could find the black water valve handle easy enough. The gray water valve handle was in an obscure place, up high on the chassis. I had to lay on my back and use a flashlight to find it. Now that I know where it's located it's rather easy to operate. I can never understand why the RV manufactures have to make the simplest of things difficult.