Fresh water tank magically fills itself

Thanks rusty. I've been under the bunk and I see what you mean. I disconnected the flex line that could fill the tank if the pump check valve failed and put it in a bucket. I ran the sink and the tub to see if it would fail and got not even a drip. Maybe one of the kids had turned the pump on when I got sprayed before. Those rascals cause more than a few minor accidents! I'll play with it some more when my wife is back and note the final verdict. Need to replace the city water anyway, so I'll do that, but it sounds like I need a pump as well.