Quick Answer:
If you notice a sewer-like or chemical smell right after restoring water, don’t panic. Most often the issue is trapped air, dislodged sediment, or dry traps that need refilling. Work methodically: open low faucets and hose bibs first to purge air and sediment, then run cold taps and flush toilets to refill traps. Check basement drains and the vent stack. If the odor persists after flushing and checking, call a plumber.
Why This Happens
- Air introduced when the line is pressurized can push sediment and odors through pipes until it’s flushed out.
- Dry traps (P-traps) allow sewer gas into the house until fixtures are refilled with water.
- Sediment in the hot water heater can be stirred up during shutdown/startup and cause a rotten-egg smell from hot taps.
- Sputtering or gurgling fixtures can signal trapped air pockets or partial blockages that let sewer gas move about.
- If you had a longer outage or a city system issue, see advice about **Smell after city outage** for related tips.
Step-by-Step What to Do
1. Open low faucets and hose bibs first
Start with faucets and exterior hose spigots at the lowest points in your home (basement, lower floors). Opening low outlets first lets air and heavier sediment exit the system without pushing them through higher fixtures.
2. Run cold taps and flush toilets to refill all traps
After the low outlets are flowing clearly, go to each sink and shower and run the cold water until the flow is steady. Flush every toilet in the house once or twice to make sure P-traps are full. This restores the water barrier that blocks sewer gas.
3. Check basement floor drains for sputtering
Watch basement drains while you run nearby fixtures. Sputtering or burping sounds mean air pockets or a partial blockage. Pour a small bucket of water into a dry floor drain to re-establish the trap seal if needed.
4. Smell-test near the main clean-out and vent stack
Check around the main sewer clean-out in the yard or basement; if sewer gas is leaking there you may notice it. Go outside and sniff near the roof vent stack briefly — a clear vent should not be strongly odorous. Identifying the general source helps decide next steps.
5. Flush the hot water heater if needed
If the smell is strongest at hot taps, sediment in the water heater may be the cause. Follow the manufacturer’s directions to flush the tank and drain a few gallons through the drain valve to clear dislodged material. If you’re not comfortable doing this, hire a pro.
What Not to Do
- Avoid immediately pouring bleach or other strong chemicals into every drain as a first fix — bleach can react with sediment or plumbing materials and make odors worse or create harmful fumes.
- Don’t assume the smell is harmless if multiple fixtures are sputtering or gurgling; persistent odors after systematic flushing are a sign to contact a professional.
When to Call a Professional
- The smell continues after you’ve purged lines, refilled traps, and flushed the hot water heater.
- Multiple drains gurgle, sputter, or back up—this can indicate a blockage or sewer-line issue.
- You find a leak at the main clean-out, around the sewer line, or notice raw sewage or repeated backups.
Safety Notes
- Open windows and ventilate the area while diagnosing smells. Do not mix household chemicals (for example, bleach and ammonia) — harmful fumes can form.
- If you smell natural gas (sharp rotten-egg or petroleum odor different from sewer smell), leave the building and call the gas company or emergency services immediately.
- Use gloves and eye protection if you work around drain valves or the water heater drain; hot water and sediment can cause injury.
Common Homeowner Questions
- Why does my water smell like rotten eggs?
Often hydrogen sulfide from the hot water heater or sewer gas from a dry trap; flush and isolate hot versus cold sources to narrow it down. - How long will the smell last?
Usually minutes to a few hours after a proper flush; persistent odor after that needs a pro. - Can I use my plumbing while clearing the smell?
Yes, run cold taps and flush toilets as part of the clearing steps; avoid extensive use if strong sewer gas or backflow is present until resolved.
More in this topic
For more related fixes and similar symptoms, see Sewer Gas Smell from Floor Drains.