A CPAP humidifier system includes an air pump, a humidifier tank, a control valve, and an auxiliary reservoir. The humidifier tank has an air inlet opening and an air outlet opening. The air inlet opening fluidly connects to the air pump, and the air outlet opening fluidly connects to an air mask. The control valve is attached to the air outlet opening and defines both an air outlet passageway and a liquid inlet passageway. The auxiliary reservoir fluidly connects to the liquid inlet passageway for providing liquid to the humidifier tank.
