Abstract: A drain adapter assembly for joining an overflow pipe to a side wall of a bathtub for permanently sealing the overflow pipe to the tub prior to the installation of a suitable overflow trim plate. The present assembly is capable of compressing the overflow pipe to the side wall of the tub while compressibly capturing a foam gasket, thus effectively preventing water seepage between the bathtub side wall and gasket and thereby enabling the tub to be filled above its overflow opening for suitable water testing.