Quick Answer:
If you notice a foul odor coming from the sink after a repair or new fixture, it’s often caused by disturbed residue, trapped water being drained, or a P-trap/vent issue. Start with simple checks and flushing the drain; many smells clear within a few hours once residues are washed away. If the odor persists or you see leaks, take further steps or call a professional.
Why This Happens
- Work on pipes or drains can dislodge hair, grease, soap scum, and bacterial buildup. Those materials release odor when exposed to air.
- Removing or drying a P-trap during repair can let sewer gas escape until the trap refills with water.
- New parts, putty, or adhesives can give off manufacturing or curing smells that mix with existing residue.
- Poor venting or a loose connection can allow odors to travel back into the room.
Step-by-Step What to Do
1. Check for obvious leaks and re-tighten fittings
- Look under the sink for wet spots, drips, or a loose slip nut. Wipe dry and watch while someone runs water to spot leaks.
- If you find a leak, tighten the joint gently. If the leak continues, stop using the sink and prepare to call a pro.
2. Flush the drain with warm water
- Run warm — not boiling — tap water at full flow for 1–2 minutes. This helps clear disturbed residue and re-establishes the water seal in the trap.
- For a more forceful flush, fill the basin a few inches deep and release the stopper so the trap refills quickly.
3. Clean the strainer and visible trap parts
- Remove the sink strainer or pop-up stopper and clean away hair and gunk by hand (wear gloves).
- If a P-trap was removed or worked on, ensure it’s reassembled correctly and tightened; standing water should remain in the trap.
4. Ventilate and wait a short time
- Open windows or run a fan. Mild odors from putty or residual debris often fade within a few hours.
- If odor is still present after several hours, continue to the next checks.
5. Try a gentle cleaning if residue remains
- Use a cup of baking soda followed by a cup of vinegar, let sit 10–15 minutes, then flush with warm water. This is safe for most household drains and helps remove organic buildup.
- A soft drain brush can help remove stuck debris from the visible drain opening.
What Not to Do
- Do not mask odors without identifying their source. Covering the smell with air fresheners or fragrances can hide a real leak or sewer-gas issue that needs fixing.
- Avoid pouring large amounts of harsh drain chemicals, especially if you suspect plastic pipes or a trap was recently reassembled; chemicals can damage seals and are dangerous if mixed.
- Do not use boiling water on PVC or older fixtures — very hot water can soften or damage plastic connections.
When to Call a Professional
- Strong sewer-like odors that don’t clear after flushing and ventilation.
- Visible leaks, wet ceiling or floor below the sink, or water continuing to drip after tightening.
- Any time the trap was removed and you’re unsure it’s reinstalled correctly, or if the smell returns after a short time. Also consider help if the problem relates to **Sink slow after faucet install** or ongoing issues like **Drain leaks days after repair**.
Safety Notes
- Work with gloves and eye protection when cleaning drains. Use good ventilation.
- Do not mix cleaning chemicals (for example bleach and ammonia) — dangerous gases can form.
- If you smell strong sewer gas or natural gas, evacuate the area and call emergency services or your gas provider immediately. Sewer gas strong enough to cause dizziness, nausea, or headaches is a hazard and needs prompt attention.
Common Homeowner Questions
- Why did the smell start right after the repair?
Often the repair disturbed built-up residue or the trap lost water briefly; flushing usually helps. - How long should I wait before worrying?
If the smell doesn’t noticeably improve within a few hours after flushing and ventilation, investigate further or call a pro. - Can I clear this myself?
Yes for most minor cases: clean the strainer, flush with warm water, and ventilate. Call a plumber if odors persist or if you find a leak.