THANX, PHIL. I have been using the coach water pump, and the winterize port. The strange thing is that if I open a faucet, the pump turns on and does pump water from the external container. I have removed the external shower hose, and if I crack it, the pump turns on. I think if I had a hose to feed this water back to the container, the pump would gain on the return, and eventually I could add water to the tank. When you use an external pump, do you connect it to the 'pressure' port??