Gurgling from bathtub drain

Drain or fixture making gurgling or bubbling sounds

Quick Answer:

If you hear a gurgling sound when the tub drains or at other times, it usually means air is moving through the plumbing because of a partial blockage or venting issue. Try a few simple checks: run the tub alone, then run another fixture at the same time; watch nearby traps for moving water; and listen at the drain to tell whether air is being sucked out or pushed back. If the noise keeps returning or several fixtures are affected, have a plumber inspect the venting and main line safely.

Why This Happens

Common reasons for gurgling include:

  • Partial clog in the drain line that traps air and forces it through other openings.
  • Poor or blocked venting that lets air travel through traps instead of up the vent pipe.
  • Shared waste lines where one fixture’s flow disturbs the air balance in another.
  • Long sections of slow-flowing pipe that allow bubbles to form and move.

Similar sounds can come from other systems in the house, such as Bubbling noise after flushing toilet or from appliance refills like a Bubbling noise after water heater refill, which can help you narrow down whether the problem is local to the tub or part of a larger system issue.

Step-by-Step What to Do

1. Isolate the fixture

  • Run the bathtub drain by itself first. Note whether the sound appears only when the tub runs.
  • Then run another nearby fixture (sink or toilet) while the tub is draining. Does the noise change or get louder?

2. Watch nearby traps

  • Look at the water level in nearby traps (bathroom sink or floor drain). If the water level moves or bubbles, that indicates air movement through the traps from a venting or line issue.
  • If traps are dry or get sucked out, you may have trap siphoning from poor venting.

3. Listen at the drain opening

  • Place your ear near the drain opening (without inserting anything). If you hear a sucking noise as water goes down, that suggests air being pulled through the trap. If you hear a blowing or pushing sound, that suggests pressure is pushing air or water back toward the tub.
  • These clues help a plumber decide whether the vent or the drain line is the likely source.

4. Clear obvious blockages safely

  • Remove hair or debris from the visible strainer or overflow plate by hand or with pliers. A quick clean often reduces gurgling caused by small clogs.
  • Try a plunger on the tub drain if the sink and tub share a line; use steady plunges and retest.

5. Re-test and note patterns

  • Run the tub and other fixtures again. Note when the gurgle happens (only when draining, continuously, or when another fixture runs).
  • Record whether the issue appears after heavy rain, during certain times, or after using specific appliances—this information helps a pro diagnose the problem.

What Not to Do

  • Don’t pour harsh chemicals down the drain. They can damage pipes, hurt seals, and create dangerous fumes without solving venting problems.
  • Don’t cap or block vent pipes yourself. Covering vents can cause pressure imbalances, trap sewer gas, or create hazards.
  • If multiple fixtures are affected, don’t assume a local DIY fix will help—call a plumber to check venting and main line conditions rather than repeatedly trying aggressive DIY methods.

When to Call a Professional

  • If the gurgling returns after basic cleaning and plunging.
  • If you notice sewer odor, slow drains in more than one fixture, or any backups.
  • If traps are being emptied (siphoning) or several fixtures on the same line make noise when one is used.

A licensed plumber can inspect vent pipes safely (roof access, smoke or camera tests), run a camera down the drain to find blockages, and check the main sewer line if needed.

Safety Notes

  • Do not climb onto the roof to inspect vents unless you are experienced and using proper fall protection—hire a pro instead.
  • Never mix chemical drain cleaners; they can react dangerously and damage plumbing.
  • When using tools like plungers or hand augers, protect your eyes and hands and follow manufacturer instructions.

Common Homeowner Questions

  • Is gurgling dangerous? Not usually immediately dangerous, but persistent gurgling can indicate vent or drain problems that lead to odors or backups and should be checked.
  • Can I fix it myself? You can try cleaning visible debris and using a plunger, but call a plumber if the sound persists or affects multiple fixtures.
  • Will a plumber need to go on my roof? Sometimes yes—to inspect vent terminations safely—but experienced plumbers use cameras and other tests before any risky roof work.

For more related articles, see the Gurgling Sounds From Drains or Fixtures hub.

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