When you run the shower, you might notice your toilet bubbling or gurgling. This is because the shower and toilet share a common drain line. So, when there’s a blockage in the line, water or air gets backed up and bubbles into the toilet.

Common Causes of Bubbling Toilets

There are several potential causes of a bubbling toilet when the shower is running, including:

Toilet Drain Blockage: A clog in the drain line directly below the toilet can cause water or air to be pushed back into the toilet, creating a gurgling sound.

Blocked Connected Toilets: If there’s a clog downline from other toilets in the home, it can also cause the toilet to bubble when the shower is running.

Vent Stack Blockage: The vent stack is a pipe that allows air to enter the drainage system, preventing negative pressure. If the vent stack is blocked, it can create negative pressure and prevent drain water from flowing freely.

Incorrectly Installed Pipes: Drain pipes that are not graded or sloped correctly can cause waste water to move too slowly, leading to blockages and bubbling toilets.

Municipal Sewer Line Blockage: In rare cases, a clog in the municipal sewer line can cause a bubbling toilet. This is because the sewer line is shared by multiple homes, and a blockage can affect the entire neighborhood.

How to Fix a Bubbling Toilet

Depending on the cause, there are several ways to fix a bubbling toilet:

Toilet Drain Blockage:

• Plunge the toilet vigorously with a toilet flange or accordion plunger, ensuring a tight seal at the bottom.
• If plunging doesn’t work, use a toilet snake (auger) to extract the clog.

Blocked Connected Toilets:

• Plunge all toilets in the home, especially those that are connected to the same drain line as the bubbling toilet.
• Use a toilet snake or auger to clear the clog if plunging doesn’t work.

Vent Stack Blockage:

• Access the roof and locate the vent stack, which is a straight, open-ended pipe.
• Use a flashlight to check for blockages in the vent stack and clear them using a bent wire coat hanger or a drain auger.
• Flush the vent stack with water from a garden hose to remove deeper clogs.

Incorrectly Installed Pipes:

• Contact a plumber to check exposed drain lines for proper grading.
• For hidden drain lines, a sewer camera inspection may be necessary.
• If the pipes are incorrectly graded, ceilings and walls may need to be opened up to access and repair them.

Municipal Sewer Line Blockage:

• Contact your municipal sewer authority and report the problem.
• The sewer authority is responsible for clearing blockages in the sewer main line, which is located after the point where your home’s sewer lateral connects to it.

Tips:

• If plunging doesn’t stop the toilet from bubbling, seal off connected drains with duct tape before plunging again.
• Use a toilet flange plunger or accordion plunger, not a bell-shaped sink plunger.
• Plungers and snakes can dislodge sewer clogs within the first few feet of the toilet. For clogs farther down the line, contact a plumber.
• Regularly cleaning the vent stack can help prevent blockages.
• If you experience frequent bubbling toilets, it’s recommended to have your plumbing system inspected by a professional plumber.