Abstract: A valve assembly for use on the inside of an enclosed water receptacle or toilet. The valve assembly incorporates a circular valve plug with spherical seating surface to close a drain hole from the inside of the waste receptacle. A helical spring and telescoping alignment tubes urge the plug into the drain hole. A spherical joint is formed between the plug and the tubes and assists in the alignment of the plug with the drain hole. The center of rotation of the spherical joint and the spherical contact surface of said joint are located on the outside of the waste receptacle when the valve plug has engaged the edge of the drain hole.