Imagine entering your bathroom and hearing a bubbling sound. The water in your toilet bowl is bubbling up in your septic tank when you look down. A gurgling toilet is not normal, so this may appear strange and even frightening. You’ll probably do a quick Google search to see what’s causing the toilet bubbling to occur when the shower is running or when I drain the bathtub, and possibly ask if you should call a plumber or your water company after taking a moment to question why this might be happening and checking to see if anything else in your bathroom is making similar noises.

A lack of airflow in your sewer line via a vent pipe is the primary cause of bubbling water in your toilet bowl. Bubbles will form in your toilet bowl as air tries to escape if something is obstructing one of your sewer lines or a vent stack. A clogged sewer pipe and a blocked vent pipe from another obstruction on the roof opening are the two main causes of vent pipe clogging.

Why is my Toilet Bubbling When the Shower is Running

When the shower is running or when you drain your bathtub, your toilet is probably bubbling. It is a common issue that many homeowners are unable to resolve.

If you’re like most people, you don’t want to think about what’s going on in your bathroom behind the scenes. But it’s difficult to ignore when your toilet begins bubbling whenever your shower is running, you drain the bathtub, or you run the bathroom sink.

So, why does it happen? Let’s begin with the most common cause.

Why Does a Toilet Gurgle? There are Only 3 Reasons 

Reason #1: A Clogged Venting System

A clogged vent can result in an ongoing air cycle that forces water out of your toilet. An air vent is a pipe that runs from the main drain or sewer line into your home to provide ventilation.

Clogging can occur when leaves, dirt, and twigs enter the venting system. When this occurs, the air cannot escape and is forced in until there is insufficient pressure to force it out through the toilet.

Until you unclog or replace the vent, the lack of air pressure will cause your toilet to bubble whenever the shower runs.

Solution: Fixing a Clogged Vent 

We recommend that you hire a professional plumber to fix this problem, but if you want to do it yourself, here’s what you need to do. To clear your drainage vents, which typically come through the roof of your house, you will need to rent the appropriate cable machine and then clear the vent from the top of your house.
This can be hazardous work, so we strongly advise hiring a professional to handle the situation.

Reason #2: Clogged Sewer line

A clogged sewer drain line has the same impact as a clogged vent. If there is a blockage in your mainline, also known as the stack, the wastewater will not drain properly, resulting in gurgling and bubbling in your toilet when you use the shower, bath, or sink.

This problem arises as a result of waste buildup inside the pipes, tree roots growing into your lines, or an improper installation in which the pipes were not sloped sufficiently.
When someone takes a shower, water will be forced out of the toilet if the drain line is too small, which can lead to a blockage.

If your sewer drain line becomes clogged, you must contact a professional plumber. Again, you should never attempt home repairs if you lack the necessary skills.

Reason #3: Incorrect Drainage System Slope

If your mainline is in good condition but you still have water bubbling out of your toilet when the sink or shower drains, the issue may be the way you’ve installed your plumbing.

Gurgling toilets are caused by improper installation or faulty grade lines. If your sewer line is not properly graded, for example, it will fill with water and not drain properly, resulting in bubbles every time someone flushes the toilet.

To fix this, you will need a plumber to perform a camera inspection on the sewer line to determine what is causing the problems so that a permanent repair can be performed.

Why is My Toilet Bubbling Septic Tank

People generally use their senses to detect signs of an impending problem. Anything out of the ordinary, especially within our own homes, automatically alerts us to the fact that something is wrong. As homeowners, we are aware that problems in the bathroom are common. However, it is simple to determine if the system is malfunctioning.

Why is my toilet bubbling in a septic tank? This could be due to a variety of factors. To summarize, something is impeding the movement of air and water in the system.

Most Common Reasons Why is My Toilet Bubbling Septic Tank

#1. Clog in the toilet or drain pipes/main sewer line

No unnecessary noise is made by a normal, flowing toilet. If your toilet, drain pipes, or mainline is gurgling, a clog may be present.

This problem is also indicated by a bubbling septic tank toilet. This occurs when non-biodegradable items such as oils, greases, sanitary pads, and wet wipes are disposed of directly in the toilet.

To solve such issues, insert a plunger into the drain line. Toilet snake tools or a plumbing auger can be used to unclog a septic tank drain pipe for larger blockages in deeper areas.

#2. Blockage in the vent pipe

The vent pipe is in charge of controlling the air pressure in a septic system. This is also where the gas can escape. Vents, like drain pipes, can become clogged or damaged. If there is an obstruction or if it is broken, the air will find another way out, such as your toilet, causing a gurgling noise.

#3. Low water level

Low water levels could be the cause of gurgling toilets. Check the water level in the toilet’s cistern and bowl. Insufficient water means low pressure, which increases the likelihood of a clog.

#4. The septic tank is full

The toilet also makes a bubbling sound when the septic tank is full. This is because the solid waste and grease will obstruct the flow of water from the tank to the drain field. Your clothes washer may have an impact on the septic system in addition to the toilet. Because there is a significant amount of wastewater released from your washer when it drains, the septic tank tends to malfunction.

When a tank is overflowing, the water cannot flow properly. However, because the wastewater has nowhere to go, it will eventually end up back at your house via the drains and toilets.

#5. Floodwater fills the drain field

The septic tank may be filled with water after heavy rain. Because the drain field is already saturated with rainwater, the system could no longer function properly. As a result, the septic waste would begin to back up. This may be another reason why your toilet is making a strange noise.

Why is My Toilet Bubbling When I Drain The Bathtub

When your plumbing system functions properly, it’s easy to forget about it. When a problem arises, however, the plumbing becomes all you can think about until the problem is resolved.
If you drain the bathtub, you might notice the toilet bubbling. Learn more about what may be causing this issue and how to resolve it.

What Causes Toilet Bubbling When I Drain the Bathtub?

To prevent pressure buildup and to vent sewer gases outside, plumbing codes require that each drain be vented separately. A single vent pipe may, however, facilitate multiple drains, including the tub, sink, and toilet, when several fixtures are close together in the bathroom.

When there is a blockage in this type of configuration, air may enter and exit through one fixture while you are using another. When the bathtub drains, this causes the toilet to bubble. Also, when a blockage forms in a wet ventilated system, you may notice that all bathroom fixtures drain slowly and the toilet flushes slowly.

How to Troubleshoot Air Bubbles in the Toilet Bowl

The clog that is causing the air bubbles in the toilet can be minor or severe. Follow these troubleshooting tips to determine the severity of the problem.

#1. The shower drain should be cleaned.

Remove the strainer and clean it of any hair or soap scum. Then, put a plumbing snake in the drain. This removes obstacles a foot or two down.

Fill the tub with a few inches of water and plug it in. Release the plug while keeping an eye on the toilet as the water drains. The blockage is deeper if the bubbling continues.

#2. Clean further down the drain

Pouring drain cleaning chemicals down the shower drain is one option, but we don’t recommend it because chemical cleaners can deteriorate your plumbing over time. Furthermore, do you want to introduce all of those chemicals into the drinking water supply?

Safe enzyme-based cleaners, baking soda, peroxide, or salt are preferable. A longer plumbing auger can also be used to reach deeper into the plumbing system. Of course, if the toilet is bubbling, it is also affected, so plunging the toilet may be beneficial in clearing the obstruction.

#3. Clean the vent

If your efforts to clear the plumbing fail, the blockage may be in the vent. The main vent stack should exit through the roof. If you go there, you might find leaves or other debris blocking the vent.
Remove any surface debris and spray water down the vent to help clear any further obstructions. If the vent overflows, use a plumbing auger to clear any clogs. After clearing, consider installing a protective screen over the plumbing vent to prevent a repeat occurrence.

When to Call a Plumber for Assistance

Some toilet bubbling issues necessitate the assistance of a plumber. Clogs further down the sewer drain can be difficult to remove at times. Because the clog is too far down the line, even if you plunge the toilet, the pressure generated may not be sufficient to clear it. Fortunately, your plumber can reach these difficult-to-remove clogs by running a toilet auger down the drain pipe.

Another situation in which you will require professional assistance is when a sewer line is damaged. Sewer lines can wear out, crack, or break over time. Tree roots can also be a problem because they will grow around sewer lines when there are leaks and even get into pipes, where they will continue to grow until the sewer line is clogged.

A sewer camera inspection is frequently required to determine the source of sewer line problems. Once the source of the problem is identified, your plumber can easily resolve it by unclogging the line or replacing the damaged section with a new sewer pipe.

If your toilet tank or toilet bowl is cracked or damaged, allowing excess water to enter the toilet water, this is another type of toilet gurgling or bubbling issue you may need assistance with. To resolve this issue, you will need to replace the tank, bowl, or entire toilet.

Finally, most residential plumbing systems will include a backflow preventer in the sewer line. This plumbing component is typically installed where wastewater exits the home. It is intended to close and prevent sewer water from flowing back up the pipes.

Should I plunge into a gurgling toilet?

Yes. If the gurgling is caused by a clog in the drain pipe, simply plunging the toilet may be enough to dislodge a light-to-moderate clog, such as one caused by flushing cotton-tip swabs that became wedged in the drain pipe.

Why does my toilet make noise?

If your toilet is making noise when it is not in use, it is most likely due to a worn or faulty flapper. If the flapper isn’t working properly, your toilet will run constantly, making noise and ultimately increasing your water bill. Replace the flapper.

Does a gurgling toilet mean the septic tank is full?

Yes. This indicates that the tank is full and must be pumped. The gurgling is caused by the septic tank being too full of solids and therefore unable to function properly. Gurgling noises can also be caused by a septic drain field failure.

How do I know if my main line is clogged?

Here are a few indicators that your main line is clogged.

  • Multiple slow-running drains
  • Water backing up into other drains.
  • Gurgling noises.
  • Drain odors that smell like sewage.


You can try to fix the problem yourself, but you may end up with a large plumbing bill. If you are unfamiliar with such a situation, you should probably call in a professional plumber.

Your vent will be unclogged or replaced by a plumbing technician. They may need to re-level and repipe the toilet or any piping that has been improperly installed or graded.


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