Slow drain only in bathroom sink

Quick Answer:

If only the bathroom sink is slow and other fixtures are fine, it’s almost always a local issue in the sink drain or trap. Start by testing other fixtures to confirm the problem is isolated, then clear the stopper and P‑trap, and use a plunger or hand snake before calling a pro.

Why This Happens

Hair, soap scum, toothpaste, and small debris collect inside the pop‑up stopper, tailpiece, or P‑trap and restrict flow.
A partially clogged P‑trap can slow drainage while other drains remain normal because the clog is local to that drain.
Issues with the stopper mechanism or an obstructed overflow can change how quickly water leaves the sink.
Worn or misaligned parts in the drain assembly can trap debris or restrict flow.
If the pattern developed slowly or changes over time, related articles such as Bathroom sink drains slower over time may help. If the sink clears briefly then slows again, see Bathroom sink drains slow then speeds up.

Step-by-Step What to Do

Step 1 — Confirm it’s isolated

Run the shower, other bathroom sink, and kitchen sink for a few seconds. If they drain normally, the issue is confined to this sink.
Testing other fixtures first avoids incorrect assumptions about the main sewer line.

Step 2 — Remove and clean the stopper

Most pop‑up stoppers lift out after releasing the pivot rod under the sink. Clear hair and gunk and rinse the stopper.
If you don’t know how your stopper detaches, look for a pivot rod behind the tailpiece and loosen the retaining nut slightly.

Step 3 — Use a plunger

Plug the overflow hole with a rag, fill the sink with a few inches of water, and plunge the drain firmly 10–15 times.
Plunging can dislodge soft clogs in the tailpiece or P‑trap.

Step 4 — Inspect and clean the P‑trap

Place a bucket under the trap, loosen the trap nuts, and remove the trap. Clean out hair and debris, then reinstall the trap securely.
Check washers and replace if cracked or leaking.

Step 5 — Try a hand snake or wire coat hanger

Feed a hand auger or a straightened coat hanger down the drain to pull out or break up blockages inside the tailpiece and trap arm.
Be gentle to avoid scratching metal or damaging plastic parts.

Step 6 — Test and repeat if needed

Reassemble and run water to test. If still slow, repeat cleaning the trap or try a longer snake before moving to tougher measures.

What Not to Do

Do not assume main line issue — when other fixtures drain normally, the main sewer is likely fine.
Do not pour commercial chemical drain cleaners into the sink. They can damage pipes, finishes, and are unsafe for you and the environment.
Do not force fittings or overtighten plastic nuts; that can crack parts and cause leaks.
Do not push power tools or long snakes into the drain without experience; you can damage the plumbing or trap seals.

When to Call a Professional

If you can’t remove the clog after cleaning the stopper and P‑trap, a plumber can inspect and snake deeper sections safely.
If you find recurring clogs despite cleaning, or there’s a leak after reassembly, call a pro to check drain alignment and seals.
If multiple fixtures become slow or you smell sewage, contact a plumber promptly — that could indicate a larger drain or vent issue.

Safety Notes

Wear gloves and eye protection when working under the sink to avoid contact with debris and dirty water.
Turn off water supply lines if you need to remove fittings or risk spraying water.
Avoid mixing chemical cleaners with other products; fumes can be harmful. If chemicals were used previously, ventilate the area before working on the drain.

Common Homeowner Questions

Why is my bathroom sink slow but the shower is fine? — The clog is usually local to the sink’s stopper, tailpiece, or P‑trap, not the main line.
Can I clear this myself or do I need a plumber? — Most isolated slow sinks can be fixed by removing the stopper and cleaning the P‑trap; call a plumber if that doesn’t clear it.
Is it safe to use chemical drain cleaners now? — No. Chemical cleaners can damage pipes and finishes; use mechanical methods first and call a pro if needed.