Quick Answer:
Right after a city water outage you may notice a smell at the sink. Before assuming debris entered the drain system, run water and flush the drain repeatedly for several minutes to clear dislodged sediment and refill traps. If the odor remains after flushing and basic checks, proceed with the steps below or call a plumber.
Why This Happens
Water outages change pressure and flow in municipal pipes. That can dislodge sediment, biofilm, or small bits of debris and push them into home lines. Low pressure can also let water in traps evaporate, allowing sewer gas to escape. In many cases the problem is temporary and related to flow or trapped material rather than a broken pipe.
If the smell seems localized to the sink’s overflow or a nearby area, check resources on Odor from overflow hole. If the smell is only at the basin and not elsewhere in the house, see Sewer odor only in sink.
Step-by-Step What to Do
1. Stay calm and gather basic info
- Note when the outage ended and when the smell started.
- Check whether other fixtures (toilets, bathtub) also smell or are affected.
- Do not make hasty repairs before flushing lines.
2. Flush the drain repeatedly
- Turn on the hot and cold water and let it run for 3–5 minutes. Repeat this cycle a few times.
- Run water in nearby fixtures (shower, tub, other sinks) to restore flow through shared lines.
- This often clears sediment and restores the water seal in traps—do this before judging the source of the odor.
3. Clean the sink strainer and overflow
- Remove and rinse the sink strainer or stopper; trapped gunk can smell when disturbed.
- Use a cloth or a soft brush to wipe the overflow opening; avoid pushing objects deep into the hole.
4. Smell test and isolation
- After flushing, sniff again to see if the odor is reduced or gone.
- Close the sink drain or plug the trap and check if the smell persists—this helps locate whether it’s the sink or a wider plumbing issue.
5. Check visible plumbing and vents
- Look under the sink for leaks or water around the P-trap. A dry or leaking trap can let sewer gas in.
- If you can safely access the roof, note whether the vent stack is obstructed (only if you are comfortable doing so; otherwise skip to the next step).
6. If the smell persists, escalate cautiously
- A persistent sewer smell after flushing can indicate a trapped debris, a damaged trap, or a venting issue. If you are uncomfortable working on the P-trap, stop and call a pro.
- A plumber can inspect deeper with a camera and clean or repair what’s needed.
What Not to Do
- Do not panic after outages; debris may need flushing first.
- Do not force sharp tools or coat-hanger wire into the drain—this can damage pipes and push debris further in.
- Do not mix strong chemicals. Pouring multiple chemical cleaners can create hazardous fumes and may harm pipes or fixtures.
When to Call a Professional
- Smell persists after thorough flushing and basic cleaning.
- Multiple fixtures have sewage odors or you see sewage backing up in drains or toilets.
- You find a leak, damaged trap, or you can’t access venting or deeper pipe sections safely.
- There are health concerns from strong sewer gases or visible contamination.
Safety Notes
- Sewer gases can be unpleasant and potentially harmful; ventilate the area by opening windows and doors.
- Wear gloves when handling trap parts or dirty strainers. Wash hands afterward.
- Avoid mixing household chemicals. If you’ve used cleaners, allow time for fumes to clear before working under the sink.
Common Homeowner Questions
- Why did the smell start right after the outage? — Pressure changes and dislodged sediment during the outage commonly cause temporary odors.
- How long should I flush before worrying? — Run water for several minutes and repeat a couple of cycles; if the smell is gone you’re likely fine.
- Can I fix this myself? — You can try flushing, cleaning the strainer, and checking the P-trap; call a plumber if the smell persists or if you find leaks.