Why Does My Toilet Gurgle When I Flush

toilet gurgle flush

Why Do I Hear “Gurgling” When I Flush The Toilet?

We expect our plumbing appliances to work well and as quietly as possible. Toilets should not gurgle or talk back to you when you flush. When that happens, you are hearing air struggling to flow properly through the line. This can have several causes, each of which have a different solution. For this reason, we recommend calling Ben Franklin Plumbing in the Bay Area to resolve a gurgling toilet. Our professional team can rapidly pinpoint the problem and fix it as quickly and as affordably as possible.

Gurgling: It’s About the Air

When we think about our plumbing system, we most often think about water, waste, pipes and gravity. However, all these elements are dependent upon air to work. Air provides the balance of pressure necessary for liquids to flow.

You’ve probably noticed this before: stick a drinking straw in water and pull it back out. The straw fills with water when you dipped it in, but then immediately released the water when you pulled it out. But if you put your finger over the straw hole before you dipped it, the air in the straw would prevent any water from entering. Conversely, if you put the straw in the water and then cover the opening with your finger and remove the straw, the water in the straw is locked in by the air trapped above it and won’t drain out by gravity.

Gurgling occurs when air tries to force its way through liquid to equalize the pressure between air and water. The sound reveals that there is a blockage or constriction somewhere in the line of fresh water or waste material and there is a partial airlock or negative air pressure that produces a sound you can hear. Remember that “negative air pressure” simply means air pressure that forces water up, not down.

There are three main culprits to investigate.

Blockage in the Main Sewer Line

The waste pipe that runs out of your house to the street sewer system is susceptible to breakage from shifts in the earth due to quakes or tremors or shifting ground pressures from erosion or nearby excavation. But by far the most common damage, particularly in older sewer lines, is damage from tree roots seeking water and nutrients from the pipes.

If your problem is a blockage or partial blockage in the main sewer line, gurgling and/or draining issues will normally occur with more than one fixture. They all have this blockage in common. If you are experiencing this, it’s best to call Ben Franklin Plumbing for a thorough inspection. We can quickly determine if you have a blockage in the main waste line and run a root-chewing snake through the line to clear it. If that doesn’t resolve the issue, you may have either a damaged pipe or a rock or thick root blockage. In this case we can look down the line with a video attachment to determine exactly what is preventing the normal flow of wastewater and advise you of the best way to resolve it.

Toilet Blockage

If you only notice a gurgling in one toilet, the issue could be very local. Toilets get a lot of abuse from items that should not be flushed down them. Cotton-tip swabs, feminine hygiene products, paper towels and even toys and stuffed animals from adventurous children have all found their way down toilets.

The first thing to do is use a plunger. First, seal off the drains in nearby fixtures such as the sink and tub or shower. This helps force the pressure of your plunging directly onto the blockage, without the possibility of escape through nearby drains. Fill the bowl with water and plunge directly over the drain hole with a dozen strong pumps. If this doesn’t resolve the issue, there may still be a clog in the toilet itself and is resistant to plunging, such as a solid object wedged firmly in place.

Borrow or buy a manual toilet auger that you can crank through the toilet drain. If it meets resistance, mark the top point on the cable and reel it back in. This will give you an idea as to where the clog is. If it is inside the toilet itself, you will need to have the toilet removed to clean the obstruction.

Municipal Sewer Line Clogs

Although these are rarer than other clogs, they can happen, especially when construction is being done nearby. Speak with your neighbors and ask them if they are having the same issues. If they are, call your municipal agency to report the problem. The solution is out of your hands, but so is the expense required to fix it.

Vent Stack Blockage

The small pipes sticking out of your roof are vent stacks designed to equalize the air pressure in drain pipes. Think back on the example of the straws. It’s the same principle. If a vent stack is blocked, draining is slow and that may be causing the gurgling sound in your toilet.

Examining vent stacks requires getting up on the roof, so we recommend calling a professional from our team at Ben Franklin Plumbing to perform this inspection. Vent pipes are needed to supply air for the complex system of drains in your home, so there will be more than one of them on the roof. Clogs can come from anything from leaves and branches to animal nests.

Clogs close to the opening can usually be removed with a hook and wire, but deeper debris will require a jet stream of water from your garden hose. Clogs that are dislodged should travel down into the waste pipe system and are flushed away.


Although a gurgling toilet usually has an inexpensive fix, addressing it should not be delayed. Because it indicates excessive or misaligned pressure in the plumbing system, it can lead to more serious and much more expensive issues in time. When you call Ben Franklin Plumbing to fix the issue, we will inspect your system for related issues or other damage caused by the blockage so that repairs are done right the first time and you can relax with your problem solved, quickly and affordably.