Problems with gurgling can arise if a sudden flow of water inside the pipe – such as when a toilet is flushed – creates a positive pressure that causes wastewater to back up in a drainage system. This can force water and air bubbles up the drain, resulting in that tell-tale gurgling sound.
If your sink if gurgling when you flush the toilet, you have a venting problem. You can add an air admittance valve under your sink.
The cause of your toilet gurgling is a blocked line somewhere. A clog is creating negative air pressure, Instead of air flowing through the lines,the air pushes back and causes the gurgling sound. Sometimes, you'll also see the toilet water bubble.
Start by using a plunger to try and clear any basic blockages. This can often solve simple clogs. If that doesn't work, the next step is to check the P-trap under the sink. Cleaning out the P-trap can often remove debris that causes clogging.
Causes for a Gurgling Toilet
The negative air pressure can create an air vacuum or air block. When you flush the toilet, this air has to go somewhere, so it comes up the drain pipe and is released in the toilet.
Bubbling in your toilet bowl is one of the many weird ways your toilet can behave if it has a problem. Minor as it may seem, the bubbling may be a sign of a more serious problem. So, it's wise to have a reliable plumber look at it as soon as possible and make the necessary repairs.
Behind or within the Wall: In most cases, the vent pipe for a toilet should run vertically from the toilet's waste pipe (known as the closet bend) and extend upward to connect with the main vent stack or a branch vent line that ultimately exits through the roof of your home.
When you flush the toilet, it opens a valve to allow more water in. Water hammer happens when the valve suddenly shuts off, resulting in water with no place to go. This incident causes the excess water to hit the walls of your pipes at high speed, resulting in a rattling or hammering sound.
Repeated water hammer may also cause significant damage to pumps, existing valves, and instruments, lead to the catastrophic failure of gasketed joints and expansion joints, and affect the integrity of pipe walls and welded joints. Water hammer can damage fittings, joints, and connections, resulting in leaks.
One of the most common types of toilet noises is a loud groan from your pipes after you flush. This sound is usually a sign of constriction in your waterline. To solve the problem, you must identify the location of the clog.
A gurgling sound in your sink is actually the sound of trapped air trying to escape from the drain. Your pipes should not have any air trapped inside, but they can become obstructed by food items like grease, seeds, bones, and rice that shouldn't go down your drain.
A mild blockage refers to a clog in the toilet, which is often the first reason you experience drained water returning through the other outlets. When an obstruction is in the toilet, the water you flush down the outlet will find other outlets to use, eventually leading the water to come out of the sink or tub.
Gurgling sinks are usually caused by trapped air in the P-trap, clogged drains, or vent pipe issues, indicating a plumbing system problem that could escalate if not addressed.
Gurgling or “Glugging” Sounds as Water Goes Down the Drain
If any of your drains make these sounds as water exits them, a blocked vent may be the culprit. The clog restricts the amount of air that flows into the vent.
If you decide to hire a licensed plumber near you to handle the fix, you can expect to pay between $150 and $200 for this service, although it could be more depending on the severity of the problem.
You can do a simple DIY test by putting your hand over the roof vent pipe while someone flushes a toilet. You should feel suction on your hand when the toilet is flushed if the vent is clear.
If your plunging efforts haven't silenced the gurgling, or if you notice bubbles rising in your toilet bowl after flushing, the problem might lie in your plumbing's ventilation system. Vent pipes (also known as soil stacks or vent stacks) are like the lungs of your plumbing.
Prices to fix a running toilet range from $50 to $400. Sometimes, they run continuously. There can be various reasons for this, including a leaky flapper, too much water in the tank, or issues with the refill tube.
Plunging is often the first line of defense against toilet clogs and can sometimes resolve gurgling issues. Follow these steps: Ensure there's enough water in the bowl to cover the plunger head.
Contact a professional plumber to determine if your water pressure is too high. If it is, a plumber can either adjust the pressure or install a water hammer arrestor. A water hammer arrestor is a small, vertical cylinder installed on the water line that absorbs hydraulic shock — a silencer for your plumbing system.
Average Flat Rate
Some plumbing jobs are billed at a flat rate. As of 2025, the average plumber rates for larger repairs are typically between $500 to $800, while smaller jobs like repairing toilets, sinks, faucets, or bathtubs typically range from $125 to $350.