Quick Answer:
If sewage-like water is coming up through a floor drain while you’re seeing heavy storm coverage, this is often a municipal surcharge or blocked storm inlet affecting the public system. Stop water use inside the house, keep people and pets away from the contaminated area, and follow the short checklist below: check city advisories, inspect nearby storm inlets, safely cap the basement cleanout if you can, document what you see, and notify local public works immediately.
Why This Happens
During intense storms a sewer or combined storm-sewer system can become overwhelmed. Water that normally flows away in pipes can back up where the system has the weakest connection — often through basement floor drains, laundry drains, or low fixtures. Blocked or clogged street catch basins and storm inlets make the problem worse by stopping surface runoff from reaching the main drains. If you notice the timing lines up with active storm reports, the issue is likely in the municipal system rather than inside your private plumbing. For the common timing differences, see the guidance on Backup only during storms.
Step-by-Step What to Do
1. Check city or county storm advisories
- Look for alerts or service notices from the local public works or county emergency management. These often mention sewer surcharges, pump station issues, or road flooding.
- Note any reported times and locations that match your neighborhood.
2. Inspect exterior catch basins and storm inlets near the property
- From a safe position, look at the nearest street grates, curb inlets and drainage basins for obvious blockages (leaves, sediment, trash).
- Do not attempt to remove heavy obstructions in the street yourself—take photos and report what you see to public works.
3. Close or cap the basement cleanout to prevent further house entry (only if safe)
- If there is a capped basement cleanout that you can reach without entering deep or contaminated water, secure it to reduce additional sewer flow into the home.
- If accessing the cleanout would require stepping into sewage, entering standing water, or moving electrical devices, do not attempt it.
4. Record time-lapse photos and contact local public works with documentation
- Take a series of photos or short videos showing the rising water and the time on each file. Time-stamped images are especially useful.
- Call or report the issue to municipal public works and provide your documentation. Explain that the backup occurred during a known storm event and you observed surface inlet conditions.
5. Reduce flow inside and protect belongings
- Stop using toilets, washing machines, dishwashers and drains until the situation is resolved.
- Move valuables and electronics out of the affected area; place wood or furniture on blocks if safe to do so.
What Not to Do
- Do not assume the problem is private property responsibility—avoid trying to clear large municipal blockages yourself. Call a pro and notify municipal public works when backups follow a known city storm event.
- Do not enter or wade in sewage-contaminated water. It can contain bacteria, chemicals and hidden hazards.
- Do not run water or appliances that add to the sewer load until the source is known and the backup has stopped.
- Do not use makeshift repairs on public grates or try to dig out major street obstructions—leave that to municipal crews.
When to Call a Professional
- Contact a licensed plumber if sewage remains in the house after the storm subsides, or if you suspect a private line issue that continues when municipal crews report no problem.
- Call immediately if sewage has flooded rooms with electrical devices, or if you see raw sewage coming through multiple fixtures (toilets, floor drains, tubs).
- Bring a professional in for inspection and cleanup to reduce health risks and to document damage for insurance.
Safety Notes
- Raw sewage is a health hazard. Avoid contact and keep children and pets away.
- Turn off electricity to basement circuits if standing water reaches outlets or electrical equipment, but only if you can do so from dry, safe ground. If unsure, wait for a qualified electrician or utility worker.
- Wear gloves, boots and eye protection if you must handle contaminated items. Wash hands and clothes thoroughly after exposure.
- Document everything safely. If the backup continues beyond the event or recurs without storms, look into causes such as infiltration, private line collapse, or older connections; for extended rainfall scenarios review guidance on Backup after prolonged rain.
Common Homeowner Questions
- Q: Is this my responsibility to fix?
A: Not usually when it follows a city storm; contact public works and a plumber for confirmation. - Q: Can I clean up the sewage myself?
A: No—use professionals for cleanup to avoid health risks and to document damage for insurance. - Q: Will insurance cover storm-related sewer backups?
A: Coverage varies—document everything and contact your insurer as soon as possible.
More in this topic
For more related fixes and similar symptoms, see Basement Drain Backs Up Only After Rain.