Replace a Sink Pop-Up Drain Assembly

A failing pop-up drain announces itself in ways you can't ignore. The stopper won't hold water anymore, or it won't lift when you pull the lever, or there's a persistent drip under the sink that shows up as a dark ring on the cabinet floor. The good news is that pop-up assemblies are standardized, inexpensive, and completely replaceable without calling anyone. The whole mechanism—flange, body, stopper, and pivot rod—comes as a kit, and swapping it out is mostly a matter of working in the awkward space under the sink with a basin wrench and some patience. This is one of those repairs that looks intimidating until you understand what you're looking at. The pop-up assembly connects the visible drain in your sink to the P-trap below, with a pivot rod that lifts and lowers the stopper. Everything threads together with slip nuts you can turn by hand once you break them loose. An hour of work gets you a drain that seals properly and operates smoothly, and you'll have learned enough about your sink's plumbing to handle the next issue without hesitation.

1. Clear your workspace completely. Remove everything from under the sink so you have room to work. Pull up the sink stopper and set it aside. Under the sink, locate where the lift rod connects to the pivot rod via a spring clip or screw—squeeze the clip or loosen the screw and slide the rod free.
2. Free the stopper mechanism. Find the pivot rod assembly on the back of the drain body, just above the P-trap. Unscrew the plastic pivot nut by hand or with pliers—it's usually finger-tight. Pull the pivot rod straight out, which releases the stopper mechanism from inside the drain.
3. Disconnect the P-trap. Use a basin wrench or slip-joint pliers to loosen the large plastic slip nut connecting the drain tailpiece to the P-trap. Turn counterclockwise until it spins freely, then slide it up the tailpiece. Have a bucket ready—water will drain out when you separate the connection.
4. Extract the old drain body. From underneath, locate the large locknut holding the drain body to the sink. Use a basin wrench to turn it counterclockwise—this takes muscle and awkward positioning. Once loose, spin it off by hand, then push the entire drain assembly up through the sink hole from below. Clean all old putty from around the sink hole with a plastic scraper.
5. Seat the new flange. Roll a rope of plumber's putty about the thickness of a pencil and press it around the underside of the new drain flange. Insert the flange down through the sink hole from above. From below, slide the rubber gasket, then the cardboard friction ring, then the locknut onto the drain body threads. Hand-tighten the locknut, then use the basin wrench to snug it firmly while holding the flange steady from above.
6. Reconnect the P-trap. Slide the tailpiece into the drain body from below and reconnect it to the P-trap with the slip nut. Hand-tighten the nut, then give it a quarter-turn with pliers. Make sure the tailpiece is vertical and the P-trap connection is aligned without stress on the pipes.
7. Install the pivot rod. Drop the new stopper into the drain from above, aligning the hole in the bottom of the stopper shaft. From below, insert the pivot rod through the hole in the drain body and through the stopper shaft hole. Screw on the pivot nut finger-tight. Test that the stopper lifts and drops smoothly when you move the pivot rod.
8. Test the seal and connections. Attach the lift rod to the pivot rod using the spring clip or screw, choosing a hole position that gives you full stopper lift when the knob is up. Fill the sink with water and check that the stopper seals completely. Let it drain and inspect all connections below for leaks while water flows through.