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Why Is My Toilet Bubbling & Gurgling? Reasons & Fixes

plumber installing toilet bowl

A gurgling toilet may not seem troublesome if it flushes, but any hiccups in your plumbing should be cause for concern. In an interconnected system, a minor issue in one area may cause or indicate problems elsewhere.

When it comes to your plumbing, failing to quickly address the situation may lead to severe damage and costly repairs. We’ll help you prevent future problems by explaining the common causes of a bubbling and gurgling toilet and what you can do to fix it.

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Why Is My Toilet Bubbling and Gurgling?

The primary reason your toilet will start randomly bubbling and gurgling is a blockage in the drains or vent stack. Any airflow disruption can create the negative or positive pressure that sucks water into or, even worse, blows it out of your toilet. There are several places where blockages can arise, each with fixes in varying levels of difficulty.

self-made composting toilet
Image Credit: Filtered Photons, Shutterstock

Clogged Drain Line

Clogs are a common cause of toilets bubbling. Water falls through the line, either from your toilet bowl or any connected pipes like sink and tub drains but has nowhere to go when it reaches the clog. Eventually, the connection where the drain meets the vent will fill with water, trapping air in the toilet drain. As water builds up, the displaced air has nowhere left to go except back through your toilet via bubbles.

Clogged Vent Stack

The vent stack is the vertical tube that runs from your toilet drain through your roof. It regulates air pressure to allow water to drain smoothly and keep sewer gasses from moving through your plumbing and into the home. Every drain with a P-trap uses a vent stack to reduce the pressure, and you’ll notice gurgling when it has a blockage.

Typical symptoms of a blocked vent stack include a foul odor from sewer gas releasing into the home and slow draining fixtures. If you have another fixture sharing the vent with your toilet, such as the sink, you may also notice gurgling when the sink drains. Since the line can’t draw air from the tube, it sucks it from the toilet and creates a gurgling noise.

How Do I Fix My Bubbling Toilet?

A clogged toilet is relatively easy to diagnose. Flush it a few times, and, depending on where the clog sits, the toilet bowl will eventually not drain and instead fill up with water. Start fixing a clogged toilet with a plunger, giving it 10–15 quick, firm pumps to break up the blockage.

When the plunger isn’t working, you can try an auger. Inexpensive hand crank augers can reach anywhere from 3 to 50 feet down a drain and generally cost under $100. Machine-operated augers can stretch much further but also cost substantially more. Many home improvement stores also offer these for rent. Avoid using drain cleaning chemicals as these can degrade the plumbing.

Of course, the clog could be further down the line. If it’s in your house’s drain lines closer to the main line heading to the sewer connection, you may be able to access it via a cleanout somewhere under the house. You will need to remove the cleanout cap with a wrench and snake the pipe to remove the clog.

When you remove the cap, water and debris often rush out of the cleanout, so you’ll need to stand clear and set up a bucket underneath the opening. In some cases, simply removing the cap can clear out the clog. If you still can’t clear the clog when snaking the line, you will likely need to call a plumber.

The clog may also be in the municipal piping. You would need to talk to the water company about repairs. It’s a city issue if you find your neighbors are having similar problems with their plumbing.

flushing water in white toilet bowl
Image Credit: Karolina Grabowska, Pexels

Fixing a Clogged Vent Stack

A sewer smell indicates that you may have a clogged vent stack. It’s not uncommon for falling leaves or birds building their nests to jam up the vent stack over time. Having nowhere to escape through the vent, rising sewer gasses will instead go out your sink, shower drain, or toilet.

The problem is exacerbated by siphoning when two drains (e.g. the toilet and sink drain) connect to the same clogged vent stack. As the toilet flushes, for instance, it will suck air from the only possible place: the sink drain. The vacuum sucks the standing water from the sink’s P-trap, creating an unobstructed path for sewer gasses to enter the bathroom.

You’ll have to get on top of your house to clean the vent with a snake. To check if the vent stack is causing the toilet to bubble and gurgle, place your hand over the stack to seal it and have someone flush the toilet. If you feel your hand getting sucked into the tube, there is no clog. No suction means a clog is blocking the incoming air from outside.

If you don’t want to get on your roof, you can try removing a section of the vent pipe in your attic and run a snake from there. DIYers will have the easiest time with PVC piping. You can easily cut it with a handsaw and repair the vent with a new section and couplers bonded by cement.

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Final Thoughts

Clogs are the culprit when you have a bubbling toilet in the drain line or the vent stack. Once you understand how pressure equalization works and how disrupting that balance can cause bubbling, you’ll have no problem finding a solution.

In some cases, DIY fixes will work to fix a gurgling toilet. Plunging a toilet only takes a few seconds, and even snaking the vent stack can be straightforward. However, there may also be underground mainline damage or more advanced plumbing issues causing the blockages. Follow these tips for finding the cause of your bubbling and gurgling toilet, and know when to reach out to a professional for a fast and efficient repair.

Featured Image Credit: Parilov, Shutterstock


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