Patent ID: 7082971

Claim:
An apparatus for maintaining a liquid level within a receptacle comprising: a liquid reservoir adapted to be positioned above a height of a liquid holding basin of the receptacle, the reservoir including an open upper end and a lower end, the open upper end including a threaded, cylindrical outer surface, and the lower end including an reservoir outlet orifice; a cap including an cylindrical wall having an enclosed top end and an open bottom end, the cylindrical wall including a threaded inner surface for engaging with the threaded outer surface of the liquid reservoir; a valve assembly provided approximate the reservoir outlet orifice of the reservoir and operatively coupled to the cap to open the reservoir outlet orifice when the cap is threaded downwardly on the reservoir to a valve-open height below an actuating height and operative to close the reservoir outlet orifice when the cap is threaded upwardly to a valve-closed height on the reservoir above the actuating height; and a circumferential seal provided radially between the reservoir and the cap when the cap is threaded at least between the valve-open height and the valve-closed height.