Fresh water is provided from external pressurized sources, or from the fresh water storage tank.
Water provided from outside the recreational vehicle is pressurized by the system from which it is delivered. When you connect your recreational vehicle to an outside soured, the fresh water tank and the water pump are kept separate from the remainder of the system by in-line check valves.
When an outside source of water is unavailable, water can be drawn from the fresh water storage tank for use in the recreational vehicle. The tank is filled through a gravity controlled water fill spout on the side of the recreational vehicle.