Why is My Toilet Bubbling When the Shower is Running?

Last Updated on June 16, 2023 by Kimberly Crawford

When a toilet bubbles or gurgles when the shower is running, it is an indication that the plumbing system is not functioning properly.

If the issue is not addressed quickly, it can lead to further complications such as a clogged drain or broken pipes, resulting in costly repairs and potential water damage.

It is important to identify the root cause of the bubbling and address it promptly to avoid further damage.

Common Causes of Toilet Bubbling When the Shower Runs

toilet bubbling
  1. Partially clogged drain line
  2. Blocked vent pipe
  3. Inadequate venting system
  4. Sewer line issues

1. Partially Clogged Drain Line

A partially clogged drain line can cause toilet bubbling when the shower is running. This happens when the water flow is blocked in the drain line, causing a build-up of pressure.

This pressure is then released through the toilet, creating the bubbling noise.

Common signs of a partially clogged drain line include slow drainage in the shower or toilet, gurgling noises when the shower is running, and a smell of sewage.

The best way to clear a clog in the drain line is with a plunger or a snake, although more serious blockages may require professional assistance.

2. Blocked Vent Pipe

Vent pipes are an essential part of a plumbing system, as they help regulate air pressure within the system and maintain the flow of water.

If a vent pipe is blocked, it can cause air to become trapped in the pipe, leading to a bubbling or gurgling sound in the toilet when the shower is running.

Signs of a blocked vent pipe include a slow draining toilet, a gurgling noise coming from the drain, and a strong sewer smell.

In order to clear the blockage, you may need to replace the pipe or use a plumbing snake to clear the clog.

Sometimes, a simple activity such as flushing the toilet can clear the blockage, but if the problem persists, it is recommended to seek professional help.

3. Inadequate Venting System

An inadequate venting system can be the culprit behind a toilet bubbling while the shower is running. This occurs when the air pressure within the drains is too high or too low.

When the shower is running, the pressure within the pipes drops, causing water to be forced into the toilet. This can cause the toilet to bubble or gurgle.

Signs of an improperly designed or installed venting system include gurgling, bubbling, and slow-draining of water from the toilet. An inadequate venting system can also cause odors to be emitted from the drains.

To improve the venting system, it is important to make sure the system is correctly designed and installed. Properly sized pipes and fittings should be used, and the vent should be secured and sealed correctly. Additionally, regular inspection and maintenance of the system should be conducted to ensure it is functioning properly.

4. Sewer Line Issues

Sewer line issues can cause toilet bubbling when the shower is running because of a problem with the water pressure caused by a blockage or obstruction in the line.

This can occur as a result of roots growing into the sewer line, a buildup of debris or waste, or a broken pipe.

The increased pressure from the shower pushes the waste back up into the toilet, causing bubbling and other signs of stress in the plumbing system.

Signs of potential sewer line issues include sewer odors, slow draining in multiple fixtures, and gurgling noises from the toilet or drains. If an obstruction is present, it may also cause the toilet to overflow or back up.

Solutions for addressing sewer line problems include clearing the obstruction, repairing or replacing the broken pipe, or replacing the piping entirely. A professional plumber can determine the cause of the issue and advise on the best solution.

Prevention and Maintenance Tips

To prevent toilet bubbling when the shower is running, it is important to inspect and clean drain lines frequently to ensure that no blockages are present.

Additionally, take care to keep the vent pipes clear of any debris or obstructions, as this can cause a disruption in the flow of water.

Proper maintenance of the plumbing system is also key in preventing bubbling and other plumbing issues, so it is recommended to follow relevant instructions and use the right products for upkeep.

If any complex issues arise, it is best to seek professional help from a licensed plumber.

When to Call a Professional Plumber

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If you experience a bubbling toilet when running the shower, it is a good idea to call a professional plumber. This could indicate a blockage in the drain pipes, or a more serious problem with your plumbing system. A plumber can diagnose the exact cause and provide a safe and effective solution.

Benefits of hiring a professional plumber include peace of mind that the job is done correctly and safely, helping to avoid further problems down the road. They can also provide more permanent solutions to problems such as fixing any underlying issues or replacing faulty parts. Hiring a professional plumber can also save time and money as they have the right tools and expertise to complete the job quickly and efficiently.

When looking for a reliable and experienced plumber, it is important to do your research. Ask for referrals from friends and family, and check online reviews to make sure the plumber you select is highly rated by their past customers. It is also important to make sure the plumber is properly licensed and insured and offers a warranty on their work.


In conclusion, toilet bubbling when the shower runs can be caused by a few common plumbing issues. These include air pressure imbalances, vent blockages, and incorrect pipe connections.

It is important to identify and address the underlying cause in order to prevent further damage or other unpleasant consequences.

Regular maintenance of your plumbing system can help ensure all fixtures are functioning properly and that any potential problems can be quickly identified and addressed.

Professional plumbing assistance may be necessary in some cases, so it is beneficial to have a reliable and experienced contractor on hand.


What causes toilet bubbling when the shower is running?

Toilet bubbling when the shower is running is most likely caused by a phenomenon known as water hammer. This occurs when the water supply to a plumbing fixture is shut off suddenly, such as when a shower is turned off. The sudden decrease in pressure causes the water to rush through the pipes, creating a knocking sound that can cause the toilet to bubble.

How can I stop toilet bubbling when the shower is running?

To stop toilet bubbling when the shower is running, try installing a water hammer arrestor. This device helps to reduce the pressure of the water and can prevent the knocking sound that causes the bubbling. You may also want to contact a professional plumber to inspect your plumbing system for any other issues that may be contributing to the bubbling.