Symptoms
- Water drains out even with the stopper closed
- Stopper looks closed but sink still empties slowly
- Sink used to hold water fine before
- Visible gap or rocking of the stopper when closed
Likely causes
- CommonWorn rubber seal on the stopperThe seal that presses against the drain opening hardens or wears with age.
- CommonDebris on the seat preventing a tight sealHair, soap scum, or mineral buildup can keep the stopper from sitting flush.
- PossibleLinkage not pulling the stopper down fullyA misadjusted pivot rod can leave the stopper slightly raised even when the knob is down.
- Less commonStopper not seated in the drain properlyCan happen if the stopper was recently removed and replaced off-center.
What to do
- Remove the stopper and clean both the stopper and the drain seat thoroughly of hair, scum, and debris.
- Inspect the rubber seal on the underside of the stopper for hardening, cracking, or flattening.
- Reinsert the stopper and test if it seals better once clean.
- If it still doesn't seal, check the pivot rod and clevis strip under the sink for correct adjustment, moving the clevis strip up or down slightly to increase downward pressure.
- Replace a worn stopper seal or the whole stopper assembly if cleaning and adjustment don't help.
- Test by filling the sink partway and watching the water level over a few minutes to confirm it holds.
Tools and parts
- Pliers
- Adjustable wrench
Pop-up drain stopper assemblySearch: “bathroom sink pop-up stopper replacement”
When to call a pro
Call a plumber if adjusting the linkage and replacing the stopper doesn't stop the leak, since the drain body itself may be worn.
Safety
Generally low risk
Generally low risk for a careful person. Stop if anything looks different from what this guide describes.