Quick Answer:
If several sinks, tubs, or toilets back up right after the city water returns while you were rinsing dishes, stop using water immediately and note the exact time service was restored. This most often points to a brief pressure surge or a clogged sewer main, and it may be local to your block or caused by storm or service recovery conditions. Follow controlled checks below and run only short, single-fixture tests before calling a pro if you see sewage or damaged hardware.
Why This Happens
When the city shuts water off and then turns it back on, pressure can spike or shift. That change can push solids or extra flow into a downstream sewer main that is already stressed or partially blocked. If a sewer main or a private lateral is overloaded, wastewater can reverse into multiple connected fixtures at once. Problems like a failed backflow preventer or a damaged pressure-reducing valve can make symptoms worse.
Similar events occur with heavy runoff or after repairs—see Backups after pressure change and Multiple fixtures back up during storms for related patterns and prevention steps.
Step-by-Step What to Do
1. Stop using water and record the time
- Turn off all taps, appliances and irrigation immediately.
- Write down the time you noticed city water was restored and when the backups started. This helps you and any utility or plumber trace the event.
2. Look for outdoor overflow
- Check yard drains, storm drains near your property, and gutter outlets for overflowing or backflow. Storm drain overflow can push into sewer lines and make indoor backups worse.
- Note whether overflow is near the street or right at your lateral cleanout.
3. Inspect any backflow preventer or pressure-reducing valve
- If you have an outdoor or basement backflow preventer or a visible pressure-reducing valve, look for cracked housings, displaced parts, or water and sewage leaking around them.
- Do not disassemble these devices yourself unless you are trained—just look for obvious damage or heavy leakage.
4. Test one fixture briefly
- After you’ve waited a short time (10–15 minutes), run a single fixture for a very short test—flush one toilet or run a sink briefly—and watch drains closely.
- If the test clears without backing up, wait and repeat once more. If any sewage appears, stop immediately.
5. Contact neighbors
- Ask a few nearby homes whether they have the same problem. If neighbors report similar backups, it’s likely a system-wide surge, main blockage, or utility issue rather than something only in your private plumbing.
- If many homes are affected, report to the water/sewer utility after you’ve documented times and observations.
What Not to Do
- Do not turn on multiple appliances, faucets, or flush many toilets at once to “flush” the system—this can overload a stressed sewer main and make backups worse.
- Do not ignore visible sewage return or a damaged backflow device—do not delay; call a professional immediately if you see sewage or hardware damage.
- Avoid poking around inside sewer cleanouts or backflow assemblies without the right tools and protective gear.
When to Call a Professional
- There is visible sewage inside any fixture or coming from fixtures after your brief tests.
- You see obvious physical damage to a backflow preventer, pressure-reducing valve, or main line access point.
- Multiple neighbors report the same issue and it persists despite stopping water use.
- There is a strong sewage smell, repeated backups, or you suspect a blockage in the main sewer line.
Safety Notes
- Sewage contains pathogens. Avoid contact, wear disposable gloves, and keep children and pets away from affected areas.
- If cleanup is needed, ventilate the area and use recommended sanitation cleaners; consider hiring a service for contaminated materials.
- If you suspect electrical equipment was exposed to sewage (basement pumps, electrical panels), turn power off at the breaker and call an electrician or plumber.
Common Homeowner Questions
- Q: Should I run my dishwasher or washing machine to test if the problem is gone?
A: No — run only a very short single-fixture test. Do not run appliances until you’re sure drains are clear. - Q: Will the city fix a sewer main backup for me?
A: If the problem is in the public main, the utility is responsible; document times and report the issue so they can investigate. - Q: Can a backflow preventer save my house from a city surge?
A: A working backflow device helps, but it can fail under severe surges or if damaged—inspect it and call a pro if you suspect problems.
More in this topic
For more related fixes and similar symptoms, see Multiple Fixtures Backing Up Together.