If you use a flexible hose outside the pole, you can fold it over to stop the flow whatever height your working.
I have a ring tied to to the pole with a bit of thin bungee. If I want to turn the water off when carrying the pole round the back, I just fold the hose and slip the ring over it. The main advantage with this system if that the ring is always in the right place,
No matter what height I am cleaning. Dai