You can fix this
Likely cause: hair and buildup on the stopper seal
Gunk on the stopper or the drain rim keeps the rubber seal from sitting flat. A good cleaning often brings the seal back.
Why this happens
Delta explains that the weight of the water presses the rubber seal under the stopper against the flange in the sink. Anything caught between the two leaves a gap. Bob Vila says a stopper that is not sealing properly can often be fixed just by cleaning the parts, and Pfister's seal check for a drain that will not hold water starts with wiping debris off the stopper's o-ring.
How to fix it
- Try lifting the stopper straight out. Danco says some simply lift out. Moen's instruction sheet shows why others do not: the pivot rod can sit next to the stopper so it pulls out for cleaning, or pass through it so it cannot be removed easily.
- If it will not lift out, you will need to open the drain. If a chemical drain cleaner has gone down this sink, stop here and call a plumber instead: Family Handyman says leftover caustic chemicals are a danger to anyone who takes the trap apart. Otherwise push the lift rod down and let the sink empty. Then close both stops under the sink so the faucet cannot be run, and set a pan or bucket under the drain pipes, as This Old House advises. If a stop will not turn, do not force it. Leave the faucet off instead.
- Once the sink is empty and the step above is done, unscrew the nut on the back of the drain and pull the rod back until the stopper lifts free. Kohler and Danco both describe it this way. Save any washers inside the nut.
- Pull off hair and wipe the stopper and its rubber seal. Pfister notes that long hair has a knack for winding itself around drains.
- Scrub the stopper with a soft brush or an old toothbrush and a mild cleaner or vinegar, as Bob Vila and Lowe's suggest. Wipe the rim of the drain opening where the seal lands.
- Check that the stopper cap is threaded fully onto its body. Pfister lists this as part of the seal check. Then look closely at the rubber seal: Lowe's says a cracked or brittle seal means the stopper should be replaced.
- Put the stopper back, slide the rod in so it catches the stopper, and snug the nut. Open the stops, pull the lift rod up and fill the sink to test.
When to stop. Do not force a stuck stopper. Bob Vila warns that too much pressure can damage a porcelain sink. If it will not come free, call a plumber.
If this does not fix it, tell the plumber
- The stopper drops and looks closed, but the sink still empties.
- Whether the sink held water while you pressed the stopper down by hand.
- Whether you cleaned the stopper and what the rubber seal looks like.
- Whether the stopper lifts out or is locked in by the rod.
Build the full list: what to tell the plumber.
Start this troubleshooter over
- Delta: Why doesn't my pop-up sink stopper stop the water from draining?
- Bob Vila: How to fix a bathroom sink stopper
- Pfister: My pop up drain is not draining water (includes does not hold water and leaking under sink)
- Danco: Pop-up stopper drain guide
- Moen: One-handle lavatory faucet instruction sheet INS10698A
- This Old House: How to fix a bath sink stopper
- Kohler: Adjusting pop-up drains
- Danco: Instructions for universal pop-up stoppers
- Lowe's: How to remove a sink drain stopper
- Family Handyman: How to clear clogged drains
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