Abstract: A drain assembly for an industrial sink that is seamlessly attached to a basin of a sink. In one embodiment, the drain assembly comprises a drain tube, drain stopper, gasket, clamp, and lever. According to one embodiment, the drain assembly is seamlessly welded to the basin of the sink so that the drain assembly and sink form one continuous unit. The drain assembly allows for external (to the sink) operation of the drain assembly via the use of a lever that is attached to the drain stopper, wherein moving the lever seals and opens the drain assembly. In one embodiment, the drain stopper is spherically-shaped with spherical wedges cut out of the top to form a disc-shaped handle.