A method of manufacturing a water heater includes providing a water heater tank having an interior and an exterior and a tank aperture communicating between the interior and exterior. A spud that defines a spud aperture extending from a first end to a second end is provided. The spud aperture is internally threaded and has a counterbore adjacent the second end. A membrane having a membrane body and a plurality of tabs extending outwardly from the membrane body is provided. The membrane is seated within the counterbore such that the tabs deform and engage a surface of the counterbore to hold the membrane in the counterbore. Thereafter, the second end of the spud is welded to the tank, such that the membrane is captured between the spud and the tank and communication between the tank aperture and the internally threaded portion of the spud aperture is obstructed by the membrane.