Ball valve at tank and just hook up hose to machine… keep machine in off position and gives it a few pulls until water starts trickling thru the bypass then fire machine up.
When i finish i shut down machine.
Close valve that feeds machine. Each one has its one valve.
Then dump extra water, i dont drive with more th.g.h an 60gl.
Then when need to power machine i just open the valve
If there is water in the tank there is no need to close the valve. The valve is only there to stop the water if you are cleaning out the filter. Even then I leave the water on to flush the screens. The last truck I set up I didn’t bother with ball valves at all. Just one more thing to leak.