How to Replace a Bathroom Sink Stopper or Drain Strainer

A bathroom sink stopper that won't hold water or a drain strainer clogged with years of buildup is one of those small failures that nags at you every time you wash your face. The good news is that replacing either one is straightforward work that doesn't require a plumber. The stopper or strainer sits right at the drain opening, held in place by a simple fastening system underneath the sink—usually just a threaded collar or mounting nut. Once you understand which type you're dealing with, the removal and installation are nearly identical. Done well, you'll have a drain that functions like new, and you'll have proven to yourself that you can handle the mechanics under your sink.

1. Protect Floor, Clear Space. Remove everything stored in or around the cabinet under your sink. Lay a towel or small bucket on the floor beneath the drain assembly to catch any water that drains or spills when you loosen the hardware. This also protects your floor from rust stains.
2. Know Your Hardware Type. Look up into the sink drain from above. If you see a visible plug that moves up and down, you have a pop-up stopper. If you see a fixed basket or mesh screen, you have a drain strainer. Now crouch under the sink and examine the hardware. A pop-up stopper will have a clevis rod (a horizontal rod with holes) connected to a pivot ball at the back of the drain assembly. A drain strainer will have a large threaded collar or locknut visible directly under the drain opening.
3. Separate Rod From Ball. If you have a pop-up stopper, locate the clevis rod attached to the pivot ball. This rod has a spring clip or a set screw holding it in place. If it's a clip, squeeze the clip and slide the rod off the pivot ball. If it's a set screw, use a Phillips screwdriver to unscrew it. Once the rod is detached, the stopper should lift freely out of the sink from above.
4. Unthread The Pivot Nut. Behind the clevis rod connection, you'll see a large nut threading onto the drain pipe. This is the pivot ball nut. Use an adjustable wrench to hold the drain pipe steady with one hand, then use a second wrench to unthread the pivot ball nut counterclockwise. As you turn, be ready for a small amount of water to drip. Once the nut is loose, unscrew it by hand and set it aside.
5. Extract Old Assembly. Under the sink, you'll see a large threaded collar or locknut clamping the drain assembly in place. This collar holds both pop-up stoppers and drain strainers. Place an adjustable wrench or basin wrench around the collar and turn counterclockwise to loosen it. Once it's loose enough to turn by hand, finish unthreading it and lift out the old strainer or stopper assembly from above. Some water will drain—this is normal.
6. Scrub Away Old Gunk. With the old strainer or stopper removed, you'll see the top of the drain opening and the underside of the sink around it. Use a damp cloth or old toothbrush to scrub away old plumber's putty, mineral deposits, and corrosion. Get the sink rim clean and dry—this ensures a watertight seal with your new strainer. If you're replacing a pop-up stopper, also wipe down the pivot ball and the inside of the drain pipe.
7. Seal With Putty Ring. Roll a rope of plumber's putty about the thickness of a pencil and long enough to wrap around the underside of your new strainer basket or stopper flange. Press the putty firmly around the entire rim. This creates a watertight seal between the strainer and the sink. Don't skimp on the putty—a broken seal will leak water into the cabinet.
8. Lower New Assembly. From above, lower the new strainer basket or stopper assembly down into the drain opening. Press down firmly and wiggle it slightly to seat it fully. You should feel the putty compress around the rim. For drain strainers, you'll see the basket or mesh screen sit flush with the sink surface. For pop-up stoppers, center the pivot ball at the back of the drain.
9. Secure Collar Tight. From under the sink, grab the threaded collar or locknut that came with your new assembly. Thread it onto the drain pipe by hand first, getting it started straight. Once it's hand-tight, use an adjustable wrench or basin wrench to finish tightening it counterclockwise. Tighten firmly but not aggressively—you want a secure seal, not stripped threads. The putty will squeeze out slightly from the rim above; this is correct.
10. Reattach Pivot Nut. If you're installing a pop-up stopper, locate the small hole on the back side of the drain assembly where the pivot ball connects. Thread the pivot ball nut back onto the drain pipe and hand-tighten it. The pivot ball should sit inside the drain assembly, and the nut should clamp it in place. Use your wrench to snug it up, but don't over-tighten—just enough that it won't rotate.
11. Reconnect Control Rod. Slide the clevis rod back onto the pivot ball and secure it with either the spring clip or set screw that was there before. The rod should move freely up and down. If your kit came with a new clevis rod, use that instead—it's likely straighter and cleaner. Adjust the rod position so that when the rod is pulled up, the stopper rises fully out of the drain, and when the rod is down, the stopper closes the drain.
12. Fill, Watch, Wipe Clean. Fill the sink with a few inches of water and observe whether it drains or holds. A new strainer or stopper should hold water without leaking into the cabinet for at least 30 seconds. Check under the sink with a flashlight to ensure no water is dripping from the collar joint. If it leaks, drain the water and tighten the collar slightly more. Once you're satisfied, use a damp cloth to wipe away the excess plumber's putty from around the rim of the sink—it hardens and looks messy if left.