I am guessing that when you say "keep the water off" you mean that you keep the water pump switch in the "off" position. If your pump short cycles, it is an indication that your system is losing water pressure. This can be caused by a small leak in the piping, a check valve in the system not holding, or some other lose of pressure. You need to do a little detective work and trace your lines to see if you have a leak.
If you have no obvious leak, my WAG would be that the check valve that prevents the water from back flowing into your supply tank is seeping back by.
I have never noticed short cycling in any of my RVs.
