Abstract: A bottled water supply system comprises a base unit into which a standard five gallon water bottle may be installed. The cover of the base unit supports the bottle in an inverted position such that the neck of the bottle projects into a water reservoir within the unit. A pump, also housed within the unit, draws water from the reservoir and pumps it to the water supply line of an appliance. Power for the pump is controlled by a pressure actuated switch so that the pressure in the supply line is maintained a predetermined level. A pair of magnetic reed switches are housed within a water tight tube in the reservoir below the normal water level. A magnetic float surrounding the tube actuates one of the reed switches when the water level falls below the neck of the water bottle, thereby actuating an alarm indicating that the bottle is empty. The second switch is actuated just before the water level drops to the level of the pump supply tube and interrupts power to the water pump.