Quick Answer:
If you hear a gurgling sound after a city outage, it often means air or pressure changes are moving through your drain system or vent pipes. Run a few simple checks: test the triggering fixture alone, then with another fixture running; watch nearby trap water levels; and listen at the drain opening to tell whether the sound is suction or pushback. If the noise keeps returning or several fixtures act up, have a plumber inspect the venting and main sewer line safely.
Why This Happens
City outages — especially those affecting pumps or water pressure — can let air enter the sewer line or change the way wastewater moves. That air can be forced through traps or pulled back through them, which makes gurgling noises. Common causes include:
- Air pockets moving through the pipes after pressure changes.
- Restricted or partially blocked venting on the roof that can’t equalize pressure quickly.
- Issues in the main sewer line or a pump station that let air in or cause intermittent back pressure.
If the sound happens only when one fixture runs, it’s often a local venting or trap issue. If it shows up with several fixtures, it points more toward shared venting or the main line — see Gurgling when multiple fixtures run for that scenario.
Step-by-Step What to Do
1. Reproduce the sound safely
- Run the fixture that makes the noise by itself (for example, a sink or bathtub) and listen. Note if the gurgle happens only when that fixture drains.
- Then run the same fixture while another fixture drains (for example, run the kitchen sink while flushing a toilet). This helps reveal whether the problem needs two fixtures to interact or occurs alone.
2. Watch trap water levels
- Look at nearby traps (the U-shaped pipe under sinks) while the triggering fixture runs. If the water level drops or splashes, air is being pulled from the trap. If it bubbles up, the line is pushing air or gas back through the trap.
- If a trap is low, pour a small amount of water into it to refill the seal and see if the gurgling stops.
3. Listen at the drain opening
- Place your ear near the drain opening (without sticking anything into the drain). A suction noise often sounds like a soft slurp; pushback or bubbling sounds like air forcing its way up with bubbling. Identifying which helps your plumber narrow down vent vs. main-line pressure issues.
4. Check other signs
- Note any sewer odor, slow drains across the house, or gurgling in multiple rooms.
- After flushing a toilet, listen for related noises — this can be similar to the common household issue of a Bubbling noise after flushing toilet.
What Not to Do
- Don’t pour harsh chemicals down the drain to “fix” gurgling. Those chemicals can damage pipes and won’t solve venting or main-line pressure problems.
- Don’t cap or seal vent pipes on your own. Blocking vents can create dangerous pressure and trap sewer gas inside your home.
- Don’t ignore repeated gurgling or smells. If multiple fixtures are affected, a plumber should check venting and main line conditions rather than trying DIY fixes that mask symptoms.
When to Call a Professional
- Call a plumber if the gurgling keeps returning after the basic checks above.
- Call right away if you notice sewer gas smells, traps losing their water seal, multiple fixtures gurgling, or slow drainage across the house.
- A plumber can inspect vents safely (roof access, cameras) and run main-line checks to find blockages, collapsed pipe sections, or problems at the municipal connection.
Safety Notes
- Sewer gas can include harmful substances. If you smell a strong rotten-egg odor or feel lightheaded, ventilate the area, leave the house, and get professional help.
- Avoid open flames or anything that could ignite gases near suspected sewer leaks.
- Do not climb onto the roof alone to check vents. Roof work is risky; leave vent inspection or removal of bird nests and debris to a safe professional.
Common Homeowner Questions
- Why did this start right after the outage?
Pressure changes and air entry into sewer lines during outages are common triggers. - Will adding water to traps fix it?
Refilling a dry trap can stop gurgling temporarily, but it won’t fix underlying vent or main-line issues. - Is the smell dangerous?
Low-level odor is unpleasant; strong or persistent sewer gas can be hazardous and needs immediate attention.
For more related articles, see the Gurgling Sounds From Drains or Fixtures hub.