What to Do If Your Bathtub Gurgles When the Toilet Flushes

If you notice that your bathtub drain makes a gurgling sound when you flush the toilet, there is no need to panic, as there are actually some easy ways to fix the issue yourself. If your bathtub gurgles when your toilet flushes, we are here to help!

What to Do If Your Bathtub Gurgles

We will start by going over some of the common causes when your bathtub gurgles when toilet flushes. From there, we will explain how you can address the issue and make your gurgling bathtub drain a thing of the past.

Trapped air is the most common cause of a gurgling bathtub. The easiest way to eliminate trapped air is by plunging the toilet. If that doesn’t work, check to ensure that the ventilation system is working correctly.

For a more permanent but labor-intensive solution, expand the size of the pipes in the plumbing system. If the air is trapped by a particularly stubborn clog causing a blocked drain, try a chemical solution like vinegar and baking soda or an off-the-shelf brand like Drano.

What Causes Gurgling in Pipes?

When it comes to a gurgling bathtub, the first step in fixing the problem is identifying the cause. In just about every situation, your bathtub gurgles for one of the following three reasons:

Air released from the bathtub drain as a result of clogged pipes. If your pipes are clogged, pressure can build, and air will be forced out of other fixtures when the toilet is flushed. This release of air can result in a gurgling noise, especially from the large drain located on the floor of your bathtub.

Air is being drawn into the bathtub drain when you flush the toilet, which can happen if your pipe vents are clogged or blocked. Again, the pressure difference forces air to flow where it should not. In this case, the bathtub vent sucks air, which results in a gurgling noise.

The bathtub does not have a P-trap to keep a specific amount of water in your bathtub pipes. If the bathtub does not have a P-trap, air will flow freely through the drainpipe when the toilet bowl is flushed, and the air pressure quickly changes inside the pipes.


How Do You Fix a Bathtub Gurgle?

Now that you know why your bathtub is creating noise when the toilet is flushed, we can look at some ways you can fix the problem.

1. Plunge the Trapped Air Out of the Drain Using a Toilet Plunger

plunge the trapped air out

As mentioned, one of the main reasons for a bathtub drain that gurgles when the toilet is flushed is that air is trapped inside the pipes. Luckily, you can usually remove this air by plunging the toilet. The plunging can push the air out of the pipes in one quick motion, rather than it being slowly vented through the bathtub drain every time you flush. The plunging can also remove the blockage causing air to get trapped in the pipes in the first place.

You will want to plunge the toilet for at least a minute, then flush and listen for the gurgling sound from your bathtub. If the noise is still there, continue plunging.

2. Check to Make Sure That Your Venting System is Working Correctly

If the gurgling sound persists after you have thoroughly plunged the toilet, you may need to take a closer look at the plumbing vent system. Given that the venting system usually has an intake on your roof, debris from outside may have become trapped inside of it.

To keep everything running smoothly, it is a good idea to clean the rooftop vent pipe at least once a year, as this will allow air to flow through it properly. Cleaning is not complicated; however, it can take a bit of effort, especially if dealing with a stubborn clog.

venting system

You can use a standard plumbing snake, which you can easily purchase at any hardware store. From there, climb on the roof and check for any obvious blockages on the screen of the vent. Remove leaves, clumps of dirt, or any other debris that could be obstructing the flow of air.

Once the screen is clean, use a garden hose to force water down the pipe, as this will help remove any obstructions inside the vent pipes. If the water will not flow and seems backed up, you will need to use your plumbing snake to dislodge the blockage. Once this is complete, you can try the hose again. If the water flows freely, the gurgling noise should cease.

3. Expanding the Pipe Diameter

If plunging the toilet and checking the venting system did nothing to stop the gurgling noise coming from your bathtub, you may need to opt for a more permanent solution.

bathroom pipes

Increasing the diameter of the drain pipes will ensure waste and water can pass through without clogging, which is almost always the cause of the gurgling noise you hear. Most residential drain pipes are 3 inches in diameter, but you can increase them to 4 inches if you regularly deal with clogging issues.

While this option is certainly more expensive and labor-intensive than the other two options, it is effective and will prevent the issue from recurring in the future.

4. Clear the Clog with a Chemical Solution

It is possible to use a chemical solution to help dissolve the clog that is causing the gurgling noise to come from your bathtub drain. While not always 100% effective, many people find this process is quick and easy, so it is always worth trying.

You can either make your own homemade solution or purchase a commercial drain clearing product, like Drano Liquid Clog Remover. If you would prefer to try a homemade solution, the following method is quite effective:

  • Pour 1 cup of white vinegar into your toilet
  • Pour an equal amount of baking soda into the toilet (1 cup)
  • After the vinegar and baking soda begin to fizz, pour roughly 1 gallon of hot water into the toilet.
  • Let the mixture sit for 12 hours. Once the time has elapsed, flush the toilet. You can also plunge the toilet at this time, as it will help to force the mixture down the drain.
  • If chemical solutions do not work, you might be dealing with a solid clog rather than one that consists of organic materials.

Final Words

While it can be annoying if your bathtub or shower drain gurgles when your toilet is flushed, it is a fairly easy problem to fix. In most cases, the noise results from a clogged toilet, so clearing that blockage will correct the problem.

Remember, prevention is just as important as correcting a gurgling drain, as you will want to make sure that it does not happen again. Be mindful of what you and others are flushing, and note that you may hear gurgling in other parts of the plumbing, like the kitchen sink or washing machine. If the problem is recurring and nothing you do seems to help, you can always reach out to a professional plumber.

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