How to Fix a Toilet That Bubbles When Flushed?

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Seeing your toilet bubble for the first time can be a bit unnerving. 

Ever wondered how to fix a toilet that bubbles when flushed? Ever wondered what causes the issue?

Well, there are a few different things that may cause it. 

To give you a bit of help, we’ve looked into how to mitigate them as quickly as possible. Keep reading to learn about what to do when your toilet bubbles when flushed.

Why Does a Toilet Bubble When Flushed?

A gurgling or bubbling toilet is usually the result of a blockage. 

A faulty component or clog can cause this blockage in the toilet or within your sewer system. In turn, the negative air pressure from the blockage creates a suction mechanism, causing air to escape back into the toilet bowl. 

The result is gurgling bubbling that you may see after flushing the toilet.

How Does a Toilet Work?

To answer this question as simply as possible, a toilet works by using a siphon mechanism and a bucket. 

The siphoning action takes place inside the toilet tank. The bucket is essentially the bowl of the toilet. When you flush, water is forced out of the bowl and into your sewer line, emptying it. 

Meanwhile, the inlet valve inside the toilet tank simultaneously allows a small amount of water to trickle through the overflow tube to refill the bowl. 

What Causes a Toilet To Bubble or Gurgle When Flushed?

The first step to fixing a bubbling toilet is to determine the source of the clog. 

To quickly resolve the problem, you can check specific parts of the toilet that are known to cause these types of clogs. Let’s discuss the most common places to start.

The Toilet Bowl

A blockage here is typically caused by something being tossed into the toilet that has no business there. This can be personal items, grooming products, entire rolls of toilet paper, or other large items. 

If you see anything floating in the toilet that is not human waste, and isn’t an appropriate amount of toilet paper, it’s always best to don a pair of rubber gloves to remove them from the toilet as soon as possible.

The Toilet Drain

The toilet drain is another common area where clogs are known to happen, and this also typically comes from items being flushed down the toilet that shouldn’t be. 

Often included are things such as feminine products, cotton swabs, too much toilet paper, baby wipes, and diapers. 

So, if your toilet bubbles when flushed, chances are that it’s because of a clog.

The Toilet’s Vent Stack

The vent stack is a vertical pipe that leads from your toilet all the way up to the roof of your home. This vent helps to control the air pressure of the sewer line and works to release exhaust gas into the air. It should be an open channel for air to escape at all times. 

However, this vent pipe can become blocked, which will cause negative air pressure inside the plumbing pipes. You may notice a gassy or rotten egg smell (a result of sewer gases) around your home or coming from your toilet if this is the case. 

The Main Line Sewer Drain

The main sewer drain of your home is where all of the drains in the home lead to. This includes the bathrooms, kitchen, and laundry area. 

The line then carries all water and waste from your home or apartment to the sewer system of your city or town. 

Blocked sewer lines are typically caused by tree roots growing inside underground sewer pipes, pipes cracking and separating, or foundational shifts in the ground beneath an area of land (also known as “home settling”).

Faulty Toilet Tank Parts

If components within your toilet become faulty, they can also cause gurgling and other toilet bubbling issues. More often than not, this will be caused by the flood and fill system. 

If you’ve never replaced this system, or the flapper — the rubber hood that opens and closes when the toilet is flushed — then chances are it may be defective and causing air pressure issues. 

Remove the lid from the toilet tank and flush it a few times to inspect these components while the toilet is flushing. When it does, the water level should be around half an inch below the overflow tube — the open pipe sticking straight up from the toilet that is usually white. 

If there isn’t enough water to touch the bottom portion, then you may need to purchase a toilet flush kit. These are relatively inexpensive and can be found at any local home improvement store. 

Air in the Lines

Sometimes you can also have air inside your plumbing lines, which can cause negative air pressure in the toilet when it’s being filled with new water. 

The air will cause the water line to spit and spurt instead of flow steadily, resulting in gurgling and bubbling in the toilet bowl itself.

You can remove air from your home’s water lines by turning on all the faucets inside the house until the toilet water begins flowing smoothly. 

After turning on the water, let it run for about 10 to 15 minutes to see if it helps resolve the problem. If it doesn’t, you may have a plumbing leak in the house, or another issue may be causing the bubbling. 

Sediment Buildup

If your toilet bubbles when flushed, sediment could also be the cause. 

Over time, sediment can build up inside of your plumbing and toilet system. This is usually due to using hard water that is heavy in magnesium or calcium. As a result, the build-up can clog your water lines with hard water scale, making your toilet bubble and gurgle as the tank fills up with water. 

The easiest and quickest way to fix this is to inspect and replace the water inlet lines inside the home if they appear discolored. They’ll typically appear reddish-orange or brown. 

You can also use a commercial cleaner such as CLR, in combination with a scrub brush or bleach, to get rid of the sediment.

How to Fix a Toilet That Bubbles

If a toilet bubbles when flushed, it’s best to take action immediately — ignoring the problem can only make it worse. 

Oftentimes, you can mitigate the issue yourself by doing a bit of simple troubleshooting. And, the great thing is, you don’t have to spend a ton of money on products and tools.

Unclog the Toilet Using a Toilet Plunger

If the toilet is clogged by your typical culprit, such as toilet paper or other items, a plunger is the quickest way to remove it. A plunger works by creating suction inside of the toilet drain line and sucking the clog out through the toilet bowl. 

This can be created by placing the plunger in the bowl and pressing it into the toilet drain a few times to create a vacuum until the clog breaks up. 

You’ll want to make sure that you get a good seal to effectively remove the clog from the toilet. This means placing the plunger directly over the drain hole and pressing it down firmly. If this does not dislodge the clog, consider moving on to a more thorough method, such as snaking the toilet. 

Snake the Drain

A toilet snake is a bit more invasive than a toilet plunger. Also known as a “toilet auger,” they can reach anywhere from 5 to 18 feet into your toilet’s drain line to get rid of even the deepest clog. 

And for serious jobs, there are also power-operated snakes available which can reach up to 100 feet into the drain. 

However, to use these longer snakes, you’ll need to remove the toilet from its base — which can take more time and be difficult if you don’t have assistance. If you don’t feel comfortable doing this, you can always contact a plumber.

Call Neighbours to Ask if They’re Experiencing Similar Problems

It never hurts to reach out to your neighbors to see if they are experiencing similar issues with their toilets. This may be the case if the issue is with the sewer’s main system.. 

If so, it may be a good idea to work in unison with them and your local sewer authority to get the issue repaired. This way you won’t have to come out of pocket for any costs.

Check and Clear the Vent Stack

The best way to clear a vent stack is to grab a ladder, climb to the top of your roof, and manually remove the clog. 

You can do this by using a garden hose to spray water down the vent stack tube. The greater the water pressure, the faster it’ll push out the blockage.

If you don’t have a sprayer gun for your garden hose, you may want to quickly go out and buy one before attempting this task, as it can save you some time. And, of course, if you’re not comfortable with climbing on your roof, you can always contact a professional.

Call a Plumber

If nothing else seems to work to fix the bubbling in your toilet, you may need to contact a licensed plumber. A professional will know immediately how to troubleshoot the issue, and they can inspect your toilet and plumbing for other potential issues. 

They also have specialized tools, such as cameras and a motorized toilet auger, to quickly chop through line-blocking tree roots and get a close look into your sewer line. 

Yes, you’ll have to come out of pocket a bit, but it’ll be more than worth it in the end if your issue is solved. 


If your toilet bubbles when flushed, it can either be a relatively easy fix or a complicated repair. Depending on the cause, there are a few different ways that you can troubleshoot this issue once you find the source of the clog. 

It’s really best not to ignore toilet gurgles, as these can lead to potentially dangerous conditions inside and around your home. 

If you aren’t comfortable with getting up close and personal with the various components of your toilet or plumbing system, you can always contact a plumber or contractor to take care of the issue for you. 

Remember though — your average plumber will typically charge at least $150 to come out to your home, so it’s best to troubleshoot the issue ahead of time if you can.

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