A toilet lavatory sink, whether free-standing or enclosed in a dressing table, includes a sink drain which connects an S-trap under the sink. Within the tailpiece before the drain connects to your S-trap, the sink also includes a pop-up lever to prevent water from going down the drain. The pop-up lever in the drain connects to an arm between the handles of the lavatory. You can install lavatory sink drains in about 15 minutes — no specialty tools or plumbing experience required.
Wipe the drain area of the sink with your hand, both above and beneath the hole, feeling for any dirt or deposits which could interfere with the drain and cause a flow. Remove any residue with a non-scratch scouring pad along with a plastic putty knife.
Apply a bead of plumber’s putty around the flange of the tailpiece. Slide the tailpiece assembly through the drain hole and then seat the flange on the lip of the drain hole.
Slide the rubber washer onto the threaded tailpiece from under the sink, followed by the steel washer. Then thread the nut on the nipple of the tailpiece till it’s hand tight. Rotate the tailpiece until the pop-up lever faces the back of the sink. Hold the tailpiece in place and tighten the nut with an adjustable wrench. Wipe away any extra plumber’s putty in the sink basin.
Catch the open end of the pop-up rod down through the hole at the center of the faucet. Slide the end of the rod through the connector at the end of the pop-up extender, and tighten the set screw to the extender to fasten the two components together.
Push up on the pop up rod about 1/2 inch. Check to see that the pop-up lever in the tailpiece is as far down as it will go. Slide the tip of the lever arm through one end of the meeting’s spring clip, followed by the nearest hole around the extender, and finally the second hole on the spring clip. Squeeze the spring clip to slip the clip onto the pop-up lever, securing the extender.
Lift the pop-up rod from above the sink, and then observe the drain stopper to find that it opens and closes properly.
Slide the end of the S-trap over the tip of the tailpiece, and tighten the coupler to securely link the two pieces. Turn the water faucet and then analyze the drain, watching for leaks under the sink.