DIY Repair & Maintenance

Solved! Why Is My Toilet Bubbling, and How Can I Fix It?

Bothersome gurgling or bubbling coming from your commode can indicate a larger problem. Troubleshoot the annoying noises with these techniques.
Glenda Taylor Avatar
closeup of inside of toilet bowl with clear bubbling water

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Q: Sometimes, my toilet makes a gurgling noise for no apparent reason—not when I flush it, but rather at random intervals. Why is my toilet bubbling, and is it safe to use the toilet while it is bubbling? How can I fix a gurgling, bubbling toilet?

A: You’re right to be concerned—that sound is not normal. When a toilet gurgles, it indicates that negative air pressure (suction) is building up in the drain line, creating an airlock of sorts.

In a well-functioning drain system, air flows freely through the lines, preventing negative air pressure, so waste runs smoothly down and out. Gurgling indicates abnormal suction building in the line. The negative air pressure will eventually release, pushing air backward through the drainpipe and into the toilet bowl. When this occurs, you’ll hear the toilet making a bubbling noise, the water in the bowl may bubble, and the toilet may flush itself.

So, what causes a toilet to gurgle? The buildup of negative air pressure is caused by a clog in one of two areas: somewhere in the drain system, which could be close to the toilet or farther down the main sewer line that connects to your community’s sewer system, or in your home’s vent stack (the pipe that allows sewer gases to escape through the roof). Depending on the severity of the clog, the remedy could be a do-it-yourself job, or you might have to call a plumber. The gurgle might not be too annoying now, but if the culprit is a broken or collapsed sewer line, it will have to be fixed—and the sooner the better. If the job is put off, waste could back up into toilets, showers, or tubs. The following guide will help you get to the root of toilet bubbling, and offer solutions to the problem.

man wearing rubber gloves plunging a toilet

First, try plunging the toilet after sealing off the drains in nearby sinks, showers, and tubs.

If the cause of the gurgling is in the drainpipe, simply plunging the toilet might create enough pressure to dislodge a light-to-moderate clog, such as one resulting from flushing cotton-tip swabs that got wedged in the drainpipe. Bathroom fixtures (tub, sink, shower) often connect to the same drain line that runs from the toilet; for this reason, you’ll want to seal off these drains with duct tape before plunging. If you plunge without sealing the drains, the pressure plunging creates can escape through other drain fixtures instead of dislodging a clog.

Start by selecting the right plunger, such as the JS Jackson accordion-style plunger, which was a top pick in our researched guide to the best plungers. With the toilet bowl full of water, fit the head of the plunger tightly to the drain hole in the bottom of the bowl. Try to dislodge the clog with 10 to 15 firm pumping motions, then wait to see if the toilet gurgles again. If it does, move on to the following steps.

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Call your neighbors to see if they, too, have bubbles coming out of the toilet.

A clog in a community sewer line could be creating gurgling toilets in your neighbors’ homes as well. If one or more of your neighbors is having similar issues, call your municipal sewer authority and report the problem. They’ll send someone out to check the sewer main, and if that’s where the problem lies, they’ll most likely cover all expenses for repairing it.

Snake the drain to remove tougher clogs.

A sewer snake (also known as a plumber’s snake or plumber’s auger) can often remove tough clogs in a drainpipe that plunging can’t manage. Featuring a long cable and a head with cutting blades for chopping through stubborn clogs, a toilet snake may have a manual or motorized crank.

A manual toilet auger ($25 to $100 at home-improvement stores) is inserted into the toilet bowl. As you turn the crank, the head works its way down the drainpipe, cutting through clogs. This type of auger is limited to the distance of its cable reach, generally 5 to 15 feet.

If a clog is so deep in the drainpipe that a small sewer snake cannot reach it, you can upgrade to a motorized model that will reach 50+ feet, or rent a medium-sized drain cleaner from a home improvement store. Renting the equipment for an afternoon might run you $40 to $50, whereas calling a plumber could run you $150 to $300 just to snake the lines (any additional repairs, such as removing tree roots that have penetrated a sewer line or fixing a broken sewer line, would set the pro price much higher). Since the auger head on a motorized sewer snake is often too large to wind its way through the toilet bowl, the toilet should be removed from its base and the auger inserted into the drainpipe at floor level. When the machine is turned on, the auger will work its way down the line, its razor-sharp blades cutting through tough clogs.

a white plastic sewer cleanout pipe in grassy yard

For clogs even deeper in the sewer line—as far out as the middle of your yard—you’ll want to auger the lines from the sewer cleanout, which is just outside of your home, directly over the sewer pipe. To locate the cleanout, check your basement or crawlspace to see where the main sewer line exits your house. Many cleanout pipes extend a few inches above the ground and feature a large PVC cap (see image, right), but others may terminate just below ground level. If that’s the case at your house, you’ll have to do a little digging to uncover it. Once you’ve removed the cap from the cleanout pipe with an adjustable wrench, auger the sewer line from there. If the toilet gurgling stops, you’ve successfully removed the sewer clog that caused it; if the sounds continue, try troubleshooting the vent stack.

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Check and clear the vent stack.

This investigation can be performed before or after you snake the drain. Because a home’s complex system of drainpipes requires an ample supply of air in order to prevent air locks in the pipes, a clog in the vent stack could be restricting airflow and causing the gurgle.

Checking and clearing the vent stack requires getting on the roof, so if you’re not completely comfortable with that, be safe and call the pros. If you want to check the vent stack yourself, you’ll need a strong flashlight, a thin rope, duct tape, and a garden hose. Tie and then duct tape a powerful, narrow flashlight to the end of a rope, turn it on, and insert it into the uncapped pipe that exits through the top of the roof. If a clog is within eight to 10 feet of the top of the pipe, you’ll often be able to see it.

Vent clogs are often caused by leaves and debris, or even the carcass of a small animal that got stuck in the pipe. If the clog is within a few feet of the top of the pipe, you may be able to remove it with a straightened-out wire coat hanger. Deeper clogs can often be removed by running water from a garden hose in the pipe, which can dislodge the clog, washing it down the pipe and out through the sewer.

RELATED: 5 Most Common Toilet Troubles and How to Fix Them

Call the plumber if your toilet bubbles despite these best efforts.

If the troubleshooting methods above failed to keep the toilet from gurgling and bubbling, it’s time to call the plumber. Plumbers have specialized equipment, such as mini cameras that drop into vent stacks for a close-up look at clogs and powerful sewer augers that can chop right through tree roots potentially clogging your main sewer line. There’s also a slim chance that the main sewer line in your yard has broken or collapsed, in which case excavation and professional repairs might be necessary.