4 Reasons Why My Toilet Is Bubbling

The plumbing system in your house is a network of pipes that serve different functions. Clean water is delivered through water lines to your sink, toilet and shower. Meanwhile, drain pipes are used to clear away the wastewater. You also have venting pipes, which take gases out of your house. These pipes work seamlessly with gravity, air pressure and water pressure to ensure you have water in your household.

Sometimes, trouble can occur in your plumbing pipes, such as clogs or slow running water. Another unique problem is a bubbling toilet bowl when the shower is running. In typical circumstances, the toilet and the shower should work independently. However, homeowners have encountered an unusual phenomenon where air bubbles emerge in the toilet every time they shower. 

Why is the toilet bubbling when the shower is bubbling? Typically, a bubbling toilet results from clogs or improper plumbing setups. However, every household is different and there might be another culprit. If you feel perplexed, it’s best to contact a plumber to diagnose the root cause, fixing the problem before the situation worsens.

Let’s learn more about why a toilet is bubbling:

Wet Venting

In a typical household, all drains are vented separately to dispense sewer gases and avoid pressure buildup. While your toilet and shower are separate fixtures, they sometimes share a drain because of their proximity. This drain may also extend upwards as a vent to the outside, also known as wet venting.

Typically, the air gets vented outwards from your shower. However, this air might channel through another nearby fixture like the toilet when a blockage occurs.  As water drains when your shower is running, the water pushes the air with it. When there is a clog, the air gets trapped and finds a way out through the toilet. When a blockage occurs, the air that should vent outward from the shower is channeled through another, nearby fixture like the toilet.

This can happen with forced air. As water drains when your shower is running, the water pushes the air with it. When there is a clog, the air gets trapped and finds a way out through the toilet. This can also happen with sucked air. With a clog, the shower water flowing to the sewer creates a vacuum and sucks air through the p-trap and escape out the toilet.

Drain Clogs

Over time, debris can build up in your plumbing system. It is a progressive issue that will eventually lead to a total clog. This clog can sometimes occur in your drain pipes.

Your drain takes away wastewater from the toilet, shower and sink, diverting it out of the house. If there is a drain clog, you may notice bubbling in the toilet bowl. This clog will be forcing negative air pressure up the line and push air or water into your toilet bowl. 

Try plunging the toilet to see if you can break up the clog. If this doesn’t work or the clog is further down the line, try a commercial clog remover or DIY solutions using baking soda, vinegar or salt. You can also use a plumber’s snake.

The clog may also be in the drain line from the shower. Remove the strainer and check to see if you can clear any debris like hair and soap scum. Use a snake or larger auger to break the clog up. You can also use commercial products and your DIY mixes.

Vent Clogs

If your drain isn’t the problem then look to your vent for build up. Vent stacks run up from the drain line and out your roof so the sewer gases can escape. They also allow air in the drain line so water stays in the P-trap and your fixtures when flushing. The P-trap holds standing water and acts as a barrier for sewer gases that could contaminate your bathroom. 

This pipe can get clogged with numerous things including leaves and debris as well as small animals like rodents and insects. While the vent usually has a cover, stuff can still get in there. As the clog becomes worse, it restricts airflow and that air has to travel somewhere. That somewhere can be your toilet.

Clearing the clog will require you to go up on the roof. You can take off the cover and try to remove any debris near the top. Pour hot water down the vent to see if that helps, but if the water rises and spills out, you may need a plumber’s auger. This is a job that you might want your plumber to tackle. They have the equipment and experience to get the issue resolved. Putting on a protective screen over the top of the vent can prevent further blockages. 

Improper Toilet Plumbing

This may be a case of plumbing not installed correctly, especially if your house is newly built. Missing vents, vents that don’t open to free air or vents running horizontally will restrict airflow and may cause your bubbling toilet. Other wrong installations can cause problems so get your plumbing inspected by a professional plumber.

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4 Reasons Why My Toilet Is Bubbling

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