Gurgling only sometimes

Intermittent gurgling with occasional air bubbles

Quick Answer:

If you hear gurgling only sometimes, it usually means air and water are moving through the drain system in an unusual way. The sound often depends on which other fixtures are running. Do a few simple tests to identify the pattern, avoid harsh chemicals, and call a plumber if you see backups, sewage smell, or gurgling from many fixtures at once.

Why This Happens

  • Partial blockages in a drain line or the main sewer can let air move past the clog and create gurgling when other fixtures run.
  • Blocked or restricted vent pipes (roof vents) let drains pull air through traps instead of through the vent, which makes gurgling as water flows.
  • Appliance timing: high-flow appliances (washing machine, dishwasher) or simultaneous flushing can change pressures and cause intermittent gurgles.
  • Seasonal issues or recent changes, for example after winter work or service interruptions, can affect vents and traps — see Gurgling after winterization for related situations.

Step-by-Step What to Do

Step 1: Note when you hear it

  • Write down which fixture you were using when the gurgle happened (toilet, kitchen sink, shower, washer, dishwasher).
  • Note whether it happens immediately, later, or only when two fixtures are used together.

Step 2: Test gurgle frequency with different fixture combinations

  • Run one fixture at a time and listen: start the kitchen sink, then stop and flush a toilet, then run a shower, then run the washing machine or dishwasher separately.
  • Test combinations: kitchen sink + toilet flush, shower + washing machine, dishwasher + sink. Record when gurgling happens and which combination causes it.
  • Try running a long, steady flow (tap full on) versus short bursts to see if flow rate matters.

Step 3: Check simple trap and drain issues

  • Make sure traps (P-traps) have water in them; pour a bucket of water into rarely used drains to refill dry traps.
  • Use a plunger on a slow sink or tub to clear small blockages. Avoid aggressive force if pipes are older.

Step 4: Inspect visible vents and outlets

  • From ground level, look for obvious roof-vent blockages like leaves or nests if you can see them safely. Do not climb on the roof alone; consider a professional for roof access.
  • If the gurgle appears only when large flows pass (washer/dishwasher), the venting may be inadequate or partially blocked.

Step 5: Try a safe, non-corrosive clearing

  • Use a drain snake for a sink or tub to remove hair and debris. For the main line, leave snaking to a pro unless you know what you’re doing.
  • After clearing, repeat the fixture combination tests to see if the pattern changed.

What Not to Do

  • Do not chase intermittents with harsh cleaners. Strong chemical drain cleaners can damage pipes and make intermittent issues worse.
  • Do not poke or force objects down vents or drains from the roof; this can push clogs further or damage vent pipes.
  • Do not ignore sewage smells, slow drains in multiple fixtures, or recurring backups—these often mean a larger problem.

When to Call a Professional

  • Call a plumber if gurgling happens in many fixtures at once, if water backs up into sinks, tubs, or toilets, or if there is a persistent sewage smell.
  • If the pattern shows gurgling only when high-flow appliances run, a pro can check venting and the main sewer line for partial blockages or improper slope.
  • After city water interruptions or other service work, if gurgling starts and simple checks don’t help, a technician can rule out issues from the public line—see also Sink gurgles after city outage.

Safety Notes

  • Do not climb onto the roof alone. Use proper ladders and fall protection or hire a professional.
  • Avoid mixing chemical cleaners and wear gloves and eye protection if you handle drain chemicals or remove debris.
  • Treat any raw sewage contact seriously: use protective gear and disinfect surfaces, and call a pro for cleanup if you have exposure or backups.

Common Homeowner Questions

  • Q: Is intermittent gurgling an emergency? A: Not always, but call a plumber if it’s accompanied by backups, sewage smell, or it affects multiple fixtures.
  • Q: Can I fix it myself? A: You can run the fixture tests, refill dry traps, and use a plunger or snake for minor clogs; leave main-line or vent work to a pro.
  • Q: Will ignoring it make it worse? A: Yes—small blockages can grow into full backups and can lead to costly repairs if left unattended.

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