Abstract: A closet flange for mounting a water closet and connecting the water closet to standard plumbing means leading to a soil pipe and vent assembly. The closet flange comprises a cylindrical body with upper and lower body portions and an axial bore. The upper body portion defines the entrance end of the body and supports an exterior annular attachment flange at the entrance end. The lower body portion defines the exit end of the body and is configured to connect with the standard plumbing means. The axial bore is provided with standard pipe threads for threaded engagement by a standard threaded screw plug to close the axial bore and seal the axial bore for air or water testing prior to installation of a water closet on the attachment flange.