Well...apparently in addition to being blind, I am also incapable of posting photos here. Anyway, I see the bottom of the tank.There's a line coming out of the lowest possible point on the tank. That seems to feed the rest of the coach, but there's a T in there (as you guys have mentioned) which feeds one of those plastic tubes that goes out through the floor. That valve is closed now...I'm assuming if I open it, it will catch any remaining water and run it out that opening, thereby draining the tank...does that make sense?