Partial clog after city outage

Quick Answer:

Toilets bubbling after a city water outage usually means air or a partial blockage in the sewer line is pushing air back through fixtures. First check if neighbors have the same problem. If it looks limited to your house, carefully open the house cleanout to release trapped air and watch the flow while someone runs water at the lowest indoor fixture to push any standing sewage toward the street. If the cleanout shows slow or no flow, contact your city to check the public main; if the utility says the main is clear, arrange a plumber camera inspection.

Why This Happens

During an outage the pressure in the public main and in service lines changes suddenly. That shift can dislodge debris, move grease or root material, and trap pockets of air in the sewer line. When the system comes back online, trapped air and displaced solids can travel toward your house and escape through the fixtures, which looks and sounds like bubbling. A partial blockage in the public main or in your lateral (the pipe between your house and the street) can make the effect worse because water and air have nowhere to go except back through drains.

Step-by-Step What to Do

1. Check with neighbors

• Ask one or two nearby homes whether they’re seeing the same bubbling or slow drains. If several houses are affected, it’s likely a municipal problem and you should notify the city utility right away.

2. Find and carefully open the house cleanout

• Locate the cleanout (often a capped pipe near the foundation, garage, or just outside the house). Put on gloves and eye protection.
• Loosen the cap slowly to release any trapped air. Have a towel and a bucket ready — a bit of sewage or smelly water may come out.
• Watch the flow: steady flow heading toward the street is a good sign. Slow or no flow suggests a blockage between your cleanout and the public main, or a blocked public main itself.

3. Run water at the lowest indoor fixture

• Run water into the lowest drain (basement floor drain, laundry sink, or utility tub) for several minutes while someone watches the cleanout. This can push standing sewage toward the street and clear trapped air pockets.

4. If cleanout flow is slow or non-existent

• Contact your city or utility and report the issue so they can inspect the public main. If the utility confirms the public main is clear, ask about arranging a plumber camera inspection of your lateral — many cities require the main to be cleared before private work begins.

For related situations see Partial clog after vacation and Partial clog only in basement for more troubleshooting steps that might apply to your home.

What Not to Do

• Don’t pour bleach or heavy chemicals into drains to “disinfect” after an outage — harsh chemicals can damage pipes, harm septic or municipal systems, and they won’t clear mechanical blockages.
• Don’t delay calling a professional when neighbors report problems, opening the cleanout shows no flow, or sewage is backing into the house. These are signs of a hazard that needs trained attention.
• Don’t stick tools or long objects into drains or the cleanout to try to clear a blockage; that can push the obstruction further or damage the pipe.

When to Call a Professional

• If multiple neighbors have the same problem, notify the city immediately so they can inspect the public main.
• If the cleanout shows little or no flow after you run the lowest fixture, call your city and be prepared to schedule a plumber camera inspection if the utility clears the public main.
• If sewage is backing into the house, there is a strong sewage smell, or you see clear signs of contamination, stop using water and call a licensed plumber right away.

Safety Notes

• Wear gloves, eye protection, and a mask if you’re opening the cleanout — sewage can carry disease and the gases are unpleasant and potentially harmful.
• Keep children and pets away from any spills. Clean and disinfect surfaces that contact sewage with appropriate cleaners after removal (follow label instructions and don’t mix chemicals).
• If you smell strong gas or suspect a hazardous situation, leave the area and call the appropriate emergency number.

Common Homeowner Questions

• Q: Why are my toilets bubbling after the outage?
  A: Bubbling is usually trapped air or a partial blockage forcing air back through drain traps.
• Q: Will the city fix it if it’s their main?
  A: Yes — if the public main is blocked the city should clear it; report the problem so they can inspect.
• Q: Can I pour bleach or chemicals down the drain to fix this?
  A: No — don’t use heavy chemicals; they won’t fix a blockage and can damage pipes and harm the system.

More in this topic

For more related fixes and similar symptoms, see Main Line Partial Clogs.