Automatic valve assembly for a water cooler reservoir

An automatic valve assembly for a water cooler having a reservoir of the type that has its upper end generally sealed to the atmosphere by a water bottle adapter that receives and supports an inverted water bottle. The valve assembly includes a ventilation passageway providing for air to enter the reservoir, and an actuator arm hingedly mounted within the interior of the water cooler. The actuator arm is operable to move between an open and a closed position in response to changing water levels within the reservoir. When in its open position the actuator arm allows the unrestricted passage of air into the reservoir through the ventilation passageway. When in its closed position the actuator arm restricts the flow of air and fluids through the ventilation passageway.