Abstract: This invention relates to an adapter for coupling a toilet bowl, such as residential toilet bowl, to a flush device that is generally utilized in a commercial close coupled water-closet combination. The adapter includes a substrate having a hole therethrough, fasteners on opposite sides of the hole for attaching the substrate to a toilet bowl, a hollow fitting extending through the hole and attached to the substrate and extending both above and below the substrate and a rigidly flexible gasket frictionally attached to the fitting below the bottom surface of the substrate. The fitting has threads on the outer surface thereof for at least that portion of the fitting that extends above the substrate. The fitting has a flared circumference on that portion of its surface below the substrate. The flexible gasket is attached to the flared circumference below the substrate to form an extension of the fitting.