Do this now
Skip the drain cleaner. The clog here is physical rather than greasy, the chemical mostly sits on top of it, and it makes the job hazardous for whoever opens the trap afterwards, which may well be you in ten minutes.
Bathroom sink draining slowly: the stopper is holding the clog
Updated
Bathroom sinks clog differently from kitchen ones. The culprit is nearly always the pop-up stopper: hair and toothpaste bind around its stem an inch or two below the plughole, and the whole mass lifts straight out once you release it. If the stopper is clean, the next stop is the trap under the sink, which is four minutes with a bucket.
- 01
Get the stopper out
Some lift straight out with a twist. Most are held by a pivot rod at the back of the drain body under the sink: unscrew the retaining nut, pull the rod back, and the stopper lifts free. Expect what comes with it to be unpleasant.
- 02
Clean the stopper and the drain body
Wipe the stem completely. Reach into the opening with a barbed drain tool or a bent piece of wire and draw out what is sitting on the crossbar below. This is the entire fix in most cases.
- 03
Flush with hot water
Run the hottest tap for a minute or two to move the toothpaste and soap film the hair was bound to. Without this it re-forms quickly on what is left behind.
- 04
If it is still slow, take the trap off
Bucket underneath, unscrew the two slip nuts by hand, and the U comes away. Empty it, clean it, check the washers are seated when it goes back. Hand tight is right; over-tightening plastic nuts cracks them.
- 05
Check the pivot rod is not the problem
If the sink drains fine with the stopper removed but slowly with it in, the pivot rod is set so the stopper never opens fully. There is an adjustment at the strap behind the drain body.
- 06
Watch for the other fixtures
If the bath or the toilet is also slow, the problem is further down the line and not in this sink. That changes what needs doing.
What it costs
| Cost | Source | |
|---|---|---|
| Barbed drain tool | about $2 to $10 | |
| Replacement pop-up assembly | about $12 to $40 | |
| Plumber clearing a sink drain | $150 to $275 | |
| Drain cleaning generally | $100 to $220 | |
| Plumber, per hour | $45 to $150 |
Every figure here is published by the source named beside it. We do not average them into a number of our own.
Where to stop
Stoppers and traps are homeowner work and need no special tools. These are not.
- Other fixtures are slow or gurgle at the same time
- That is a shared branch or the main drain, and it cannot be cleared from one sink.
- The pipes are old galvanised or cast iron
- Augering corroded pipe can punch through it, and a hole in a waste pipe in a wall is a far worse day than a slow sink.
- It backs up rather than draining slowly, or smells of sewage
- That is a main line problem and it can put waste water into the house.
- It blocks again within weeks of a proper clean
- Repeated clogs in the same spot usually mean a fault in the pipe rather than what you keep pulling out of it.
Why it happened
The pop-up stopper sits permanently in the flow with a stem and a pivot rod crossing the pipe, which is an ideal snag point. Hair catches on it, toothpaste and soap bind the mass together, and it grows downward from there. It is a design compromise: the thing that lets you fill the basin is also the thing that collects everything going down it.
What stops it happening again
Pull the stopper and wipe the stem every couple of months. It takes a minute and it catches the clog while it is still a smear rather than a plug. Run the hot tap for thirty seconds after brushing teeth, which moves the toothpaste past the trap instead of leaving it to set on the stem.
- The part
- Nothing needed. A barbed drain tool for a couple of dollars makes the job cleaner if you would rather not remove the stopper.
- How often
- Wipe the stopper every couple of months. Clear the trap once a year, or whenever the sink slows.
Want the rest of the house covered?
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Also asked
- Why is my bathroom sink draining slowly?
- Hair and toothpaste bound around the pop-up stopper stem, an inch or two below the plughole. Take the stopper out and most of the time the clog comes with it.
- How do I remove a bathroom sink stopper?
- Some twist and lift straight out. Most are held by a pivot rod behind the drain body under the sink: undo the retaining nut, pull the rod back, and lift.
- Should I use drain cleaner on a bathroom sink?
- Better not to. The clog is hair rather than grease, the chemical sits on top of it, and it makes opening the trap hazardous afterwards.
- What if cleaning the stopper does not fix it?
- Take the trap off with a bucket underneath. Two slip nuts, hand tight going back. If that is clean too, the blockage is further down the line.
- How much does a plumber charge to unclog a bathroom sink?
- HomeGuide puts clearing a sink drain at $150 to $275, and drain cleaning generally at $100 to $220. Most of it is the call-out.