What to Do If Your Toilet Gurgles at the End of a Flush

Believe it or not, most of your toilet woes can be solved without the help of a plumber. If your only toilet isn’t functioning properly, you probably wouldn’t want to wait for the cavalry to arrive. And how do you know if the problem you’re experiencing is severe enough to bother calling the professionals, anyway? For example, what do you do if your toilet occasionally gurgles at the end of a flush?

What to do if a toilet gurgles when flushing.

Even for a casual handyman, that shouldn’t be an insurmountable problem. As you’ll find out, there are plenty of things that could be causing the bubbling sound. However, all the potential issues are relatively easy to fix. Before you take the plunge(r) and put your plumbing cap on, though, let’s review which tools you might end up needing.

Get Your Plumbing Toolbox and Prepare for a Big Cleanup

If you’re undertaking a plumbing project, no matter how big or small it is, you’ll want to keep a few things on hand.

To begin with, you should find a rubber plunger and a drain snake you’re comfortable working with. If you don’t want to put in all that effort, you might get similar results with a chemical drain cleaner. And, of course, you should already have a toilet brush and bleach at home.

However, since we’re dealing with water, you should prepare for spills by getting some towels or rags, just in case. If you have to seal off the drains before plunging the toilet, you may need duct tape too. Alternatively, you could get a few more plungers and some extra pairs of hands to wield them.

Those are pretty much the basic tools you’ll need to troubleshoot your toilet problem. Once you figure out what’s causing the gurgling noise, you might find that you need other items as well. For example, you might have to replace the water inlet line or parts of the flushing system inside the toilet tank.

But we’ll cross that bridge when we get to it. For now, let’s start the troubleshooting process.

Why Your Toilet Gurgles at the End of a Flush and How to Fix It

When I go to flush my toilet, it should do so without complaint. I don’t think that’s an unreasonable request. If you’re of a similar opinion, here are some of the reasons your toilet might gurgle at the end of a flush — and a few potential solutions.

How to fix a toilet that gurgles at the end of a flush.

1. Toilet Clogs

A waste clog is one of the most common reasons a toilet might gurgle at the end of a flush. The clog may be preventing the flushed water from passing through the pipes. That, in turn, could result in some air coming back up the drain, which would produce the gurgling sound.

Since clogs are generally a fairly common problem, you should already have everything you need to resolve one. That includes all of the things I’ve listed above: a plunger, a drain snake, or a chemical clog buster. Since you probably already know how to use those things, I won’t spend much time addressing the issue.

Still, if you feel like plunging the toilet just isn’t cutting it, try again after sealing all the nearby drains. After all, those outlets share the same waste pipes with your toilet. Therefore, closing off the drains in the sink, shower, and on the bathroom floor will increase the air pressure inside the pipes as you plunge the toilet.

As I have mentioned, you can seal off all those drains either by taping them over or by having other people close them with rubber plungers. Then, try plunging again. If that doesn’t get the waste through, get the drain snake. The invasive method of sending a line down the pipe should dislodge whatever was accumulating down there.

As a preventative measure, remember not to flush items that are not waste or toilet paper. Some people have been known to flush other things, like wet wipes, cigarette butts, Q-tips, or feminine hygiene products. You might want to make sure your housemates know that they shouldn’t do that if you want to avoid clogs altogether.

2. Air Pockets in the Plumbing

As you may be aware, air plays a crucial role in modern plumbing systems. Throughout history, we’ve spent most of our time trying to figure out a way to prevent it from coming up from the sewers. And we have done exactly that, thanks to the invention of the P-trap, the bend in the pipe that uses standing water to prevent those fumes from wafting up.

So, most of our waste outlets should be dry, apart from the water that’s acting as a barrier in the P-trap. But do you know where the air isn’t supposed to be? It certainly shouldn’t be in the pipes that bring water to your taps and toilet tank. If it somehow gets in there, it can produce the kind of bubbling sound we’re trying to prevent.

But really, having air in your water lines would probably cause gurgling sounds at random times, too. You wouldn’t only hear them while the tank is refilling. The air bubbles would find a way to disrupt other water sources, as well.

Fortunately, getting them to come out is rather easy. Just turn on all the faucets on the same water line and keep them on until they stop sputtering. The next time you flush, the water should go down smoothly — unless the pipes themselves are the problem.

3. Clogged Vent Stack

In most US buildings, waste pipes go all the way up to the roof, which creates the air pressure necessary for waste to flush. However, if the opening on the roof isn’t covered, it can become clogged with leaves and other materials. Sometimes, small birds and squirrels crawl down the pipe and make their nests, restricting the airflow in the pipes. That can disrupt the air pressure in them and cause that gurgling sound.

In fact, most of your water-based appliances are probably connected to the same vent stack. So if one of them needs to expel water, it might pull air from your toilet to create the suction it needs. In that case, you’d hear the gurgling noise when your washer drains too, not only when you flush.

Unfortunately, if the clog is near the top of the vent stack, you’ll need to get on the roof to get it out. If you don’t have easy access to your roof, I don’t recommend doing this. But if you do, you’ll be able to remove the clog with a hook and wire or even your trusty drain snake.

Alternatively, you could use a strong blast of water to push it through. Your garden hose should do the trick — if it’s long enough to reach the roof.

To prevent similar clogs from forming, you can cover the vent on the roof with a piece of hardware cloth. The mesh material should prevent large debris from ending up in your pipes.

4. Sediment Buildup in the Tank

If both the air and the waste pipes are as clean as they can be, there is one last thing that might be causing the clog.

Now, here’s where you’ll have to open up the toilet tank. The first thing you should notice is the color of the water and the interior walls of the tank. If it’s anything other than what it should be — but especially reddish — you’re dealing with sediment buildup.

Basically, the iron, calcium, or magnesium in your water will form mineral deposits on the inside of the tank. You’ll know that the situation is really out of hand if you see dark, moss-like buildup. If you don’t clean it properly, it will eventually block water from entering the tank. That, in turn, can cause the fill valve to sputter and gargle as it refills the tank.

Fortunately, there’s a simple solution to this problem. You just need a scrubbing brush and a bleach solution. A thorough wash should break down the bacteria. However, if the water inlet line is beyond saving, you might have to get a new one.

5. Faulty Tank Fill System

Lastly, you might be dealing with a faulty tank fill system.

You should be able to tell whether your tank equipment is working as it should just by looking at it. However, if you don’t know what a properly functioning flush and fill system even looks like, this video shows two examples.

Keep in mind, though, that in the first one, the fill valve ought to be replaced — the water shouldn’t be spraying in all directions like that.

There are two basic mechanisms in a toilet tank: one that releases water into the bowl and one that fills the tank back up. They’re both activated when you press the flush lever or button. First, the flapper lifts to let the contents of the tank escape into the bowl. Then, the new water comes in from the pipe that connects the tank to the wall, stopping when the float presses the fill valve shut.

Suffice to say, these components should be high up on your list of suspects when trying to figure out where the gurgling sounds are coming from. For example, the flapper could be causing the gurgling by letting air into the tank.

Alternatively, it could be the fill valve. If it’s spraying in all directions like in the video above, that may be behind the bubbling sounds you’re hearing. And it would explain why you’re hearing them at the end of a flush.

Ultimately, if this is the problem you’re dealing with, you might have to replace the elements inside the tank. Fortunately, universal replacement kits are fairly easy to find and install.

Could Hearing a Gurgling Noise at the End of a Flush Be Normal?

If the problem persists, you might have to throw in the towel and call a plumber. They’ll figure out what’s wrong even if they have to send cameras down the vent stack and waste pipes.

The worst-case scenario would be if they discovered that the whole plumbing system is corrupted. If you live in an apartment building, that would mean that your neighbors are dealing with the same issue you’re experiencing.

But most of the time, hearing a gurgling noise at the end of a flush isn’t a cause for concern. It could be the result of any number of things, including the flush and fill mechanism in the tank. Even the shape of the bowl might be a factor. If you want to make sure the toilet itself isn’t to blame, you could get one with a quieter flush.

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