4 reasons why your toilet is bubbling.


By Evan Crowther

Hearing a toilet bubbling is generally a sign that something in your plumbing system isn’t working properly.  If you wonder, “Why is my toilet bubbling?” your first instinct may be to call a plumber. However, before hiring a plumbing service, you can do a few simple checks yourself. 

Here are some of the most common reasons a toilet is making a bubbling or gurgling sound. Find out what you can do to fix the problem yourself — and when it’s time to call a professional

1. Blocked vent stack.

One of the most common reasons a toilet bubbles is a blockage in the vent pipe. The vent pipe allows air to flow into the pipe so water can escape.

When this line is clogged, the negative air pressure can send the air back up to the toilet bowl. The resulting air pockets create those annoying bubbling and gurgling noises.

Reasons for a blocked vent stack include:

  • Leftover debris from a previously clogged sewer line
  • Ice blocking off the drain vent during a freeze or snowstorm
  • Animals building a nest in the pipe

A blockage in the vent stack is best left to a professional, as the repair may involve a drain snake or even going onto the roof. 

2. Clogged toilet.

In some cases, a clog in the toilet can cause a gurgling sound when you flush the toilet. This is usually because an obstruction is making it difficult for the toilet water to escape down the drain.

Toilet clogs can result from trying to flush something other than waste or toilet paper. Trying to flush too much toilet paper at once can also clog the toilet.

A clog is usually a simple DIY fix with a plunger. If the gurgling noise persists after you plunge the toilet, it may be time to hire a professional.

Related: How to unclog a toilet — with or without a plunger.

3. Problems with the sewer main.

Another reason your toilet gurgles or makes a bubbling sound could be the sewer line. When a blockage forms in your sewer line, it often affects more than one fixture. You may notice bubbling coming from:

  • Bathtubs
  • Showers
  • Toilets

To test for a sewer line clog, run the sink nearest to the toilet. If you hear bubbling or gurgling in your toilet when you run the faucet, it can indicate a sewer line clog. This occurs because water has stopped flowing freely into the sewer and instead returns to the nearest fixture.

If you have a clog in your sewer main, it’s best to shut off your home’s main water supply. You’ll most likely need to call a plumbing repair professional to clear the blockage.

4. Septic tank issues.

For homeowners with a septic tank, maintenance is crucial to prevent system failures. When something goes wrong with a septic tank, one of the first signs is gurgling sounds in your plumbing system. 

If you have an issue with your tank, it can lead to gurgling or bubbling in the toilet. Septic tanks can begin to fail for a variety of reasons, including:

  • Clog in the pipe that goes from the house to the tank
  • Drainfield failure due to overuse
  • Clogged outlet baffle or effluent filter
  • Blockage in the tank’s inlet baffle

Clogs in any component of your septic tank may also occur due to tree roots making their way into the pipes. Flushing anything other than waste and toilet paper can also lead to clogs.

Be sure to check your tank regularly for signs of wear or failure. Failing systems can contaminate your water supply and lead to severe health risks.

If you suspect a problem with your septic tank, hire a professional for an inspection right away.

Compare prices from plumbers near you.

Why is my toilet bubbling when the shower is running?

If you notice your toilet only bubbles when you run the shower or another fixture, the most common cause is a clog in the sewer line. A clogged sewer line prevents drain water from making its way into the sewage system. 

Because the water has nowhere else to go, it makes its way back into your home. If the water can’t come back up through the shower drain, it goes back up into the toilet. The result is a bubbling or gurgling noise when you run the shower.

How to fix a bubbling or gurgling toilet.

No homeowner wants to hear bubbling or gurgling noises coming from their toilet. To put a stop to the problem, follow these steps:

  • Identify the root cause of the bubbling noise. This will give you insight into the best course of action to fix the issue.
  • Shut the water supply off if you suspect a sewer main clog. If the sewer line has a clog, shutting off the water supply can stop sewage from flowing back into your home until you can repair the problem.
  • Attempt simple repairs if possible. Some causes for toilet bubbling can be repaired with a simple plunger if the issue is something simple, like a clogged toilet.
  • Call a plumber for severe issues. If the issue is something major like a clogged vent stack, you should find a nearby professional.

Tips to prevent toilet bubbling in the future.

There are a few ways to prevent issues that cause bubbling or gurgling noises:

  • Regular inspections. Have a professional inspect your plumbing periodically.
  • Proper disposal practices. Avoid flushing anything besides waste and toilet paper.
  • Repair minor issues. Repair any issues you notice before they get worse.

Hire a plumber to troubleshoot your toilet.

If you aren’t sure why your toilet is making strange sounds, a professional can help. Download the Thumbtack app today to get a free quote from a plumber in your area.


Does a gurgling toilet mean the septic tank is full?

Gurgling sounds in your plumbing often indicate an issue with the septic tank. These noises can result from a tank that’s overdue for pumping. You should have your tank pumped every 3-5 years.

Can a plunger fix a gurgling toilet?

In some cases, a bubbling toilet is the result of a simple clog that you can fix with a plunger. If your toilet still bubbles after plunging, it could indicate a more severe problem, like a clogged vent stack. 

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