When utilizing tank water delivered by the water pump while still connected to the external fresh water supply, is the water from the fawcets mixed or is the outside supply closed off? What I am trying to resolve, can I "warm" the tap water in the winter by utilizing tank water alone, while still connected to the campground water.
Depending on water pressure, you should get some of each.
I often turn the water pump on for showering in order to have higher water flow and pressure.
I think it will be which ever has the higher pressure. One way to tell is to hooked up to external water with the water pump off. Use some water so you know there is no residual pressure from the pump. Turn on water pump and listen to see if it runs. If yes then you know the pump has a higher pressure and that is what you are pulling from primarily. I say primarily because once the pressure drops (due to high flow usage) below the external supply it will be a mixture of both which is what I think Tom was referring to.