Abstract: A drain valve assembly for use with an air bath including an air distribution system and a method of cleansing channels of an air distribution system for a bath vessel. The drain valve assembly is located within an opening in the bath vessel to control the flow of water from the bath vessel to an effluent drain, to control the flow of air and water from the air distribution system to an effluent drain and to maintain a fluid pressure within the air distribution system. The drain valve assembly includes a valve housing for extending between the bath vessel and a fluid waste pipe connected to the effluent drain. The valve housing has an upper opening for positioning proximate the bath vessel and a lower opening for receiving fluid from the air bath distribution system. The drain valve assembly also includes a stopper having first and second vertically aligned plungers. The stopper is secured within the valve housing and is capable of moving relative thereto.