Why Is My Toilet Making Noise After Flushing? How to Diagnose a Finicky Toilet

Noises from your plumbing after flushing the toilet are annoying, if not alarming. And it can be pretty embarrassing to have your toilet notifying the entire house with every flush. So, what’s the deal with all the noise from the pipes when the toilet flushes? Let’s take a look at why your toilet makes noises after flushing and what you can do to fix the problem.

1. Hammer or Banging Sound a.k.a Water Hammer

A knocking or hammering noise in your pipes is a telltale symptom of water hammer. This phenomenon can also sound like a loud thud after flushing the toilet. 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.

How to Fix It

Water hammer is a noisy nuisance that can damage your pipes over time if left unaddressed. You can fix the issue by hiring a local plumber to install a water hammer arrestor, which absorbs the shock of the sudden rush of water.

2. Toilet Makes Flushing Sound on Its Own a.k.a Ghost Flushing 

If your toilet seems to be mysteriously flushing on its own, especially at regular intervals, the culprit is more likely to be a faulty flapper than a ghost. When the flapper at the bottom of your toilet tank isn’t sealed properly, water will slowly seep out of the tank into the bowl. Once the tank float sinks below a certain level, the water switches on, and your toilet will flush on its own.

How to Fix It

To determine whether the flapper is the problem, add a small amount of food dye to the water in your toilet tank and wait about 30 minutes. If any of the food coloring travels to the bowl, the flapper is the issue. You can easily replace a toilet flapper in 30 minutes or have a professional plumber address the problem.

3. Toilet Hissing 

A persistent hissing noise is a common problem in older toilets that can have a variety of causes:

• A deteriorating rubber flapper or valve seal causes the leaking.

• A misadjusted float or fill valve causes water to drain into the overflow tube.

• A malfunctioning chain is lifting and letting water run continuously.

• An uneven water supply is running from the water flow lines to the toilet.

How to Fix It

Since a toilet might be hissing for many reasons, the first step is to diagnose it properly. Start by examining the water supply valve at the base of the toilet. Adjust the flow to see if the hissing stops or the toilet flushes better. If that doesn’t solve the issue, turn off the water supply and open the lid to examine each part.

• The float and fill valve should be set below the fill line so that water doesn’t go too high and continuously drain into the overflow tube. Adjust if not.

• The flapper should create a watertight seal over the flush tube at the bottom. If sediment is built up on the flapper, remove it and see if an improved seal stops the hissing.

• The fill valve seal at the top of the tank may also have sediment buildup. Remove it to see if the hissing stops.

If any of these components are deteriorated, small holes may be the source of a leak and the hissing sound. Take your damaged part or parts to the hardware store and find a matching part to replace each of them. If your toilet still hisses, your problem may need the help of a professional plumber.

4. Groaning or Vibrating Noise When Flushing the Toilet

When you hear a vibrating noise from your pipes when the toilet flushes, this usually points to an issue with the fill valve. This piece is the part of your toilet that refills the water tank. It might also sound like a foghorn or groaning noise that continues for around 30 seconds after you flush. 

Once the toilet tank gets filled, a small diaphragm in the fill valve pushes down and cuts off the water flow. This diaphragm is made of soft, flexible material—typically rubber—which creates a tight seal to prevent the tank from overfilling. Over time, the diaphragm can become stiffer and less malleable. This change causes it to rattle around when the incoming water hits instead of staying tightly sealed as it normally would. 

If you’re hearing a humming or vibrating sound, that’s likely the source.

How to Fix It

You can diagnose a fill valve issue by following these steps: 

• Take the lid off the toilet tank.

• Flush the toilet. 

• Lift the ball float to cut off the flow of water. If the sound stops, there’s an issue with the fill valve. 

Once you’ve pinpointed the problem, you can get rid of that vibrating noise by replacing the fill valve. This task is a simple DIY toilet repair if you have the skills and tools. The new valve should have instructions for replacement. 

If you’re uncomfortable handling this alone, a local plumber can always assist you.

5. Toilet Making Rushing Water Sound

Hearing a running water noise usually means the tank is constantly filling. This sound might indicate a leak within the tank, resulting from a few different causes.

A running water noise when flushing the toilet might mean there is water leaking from the tank into the bowl. Either way, it’s important to address this issue to prevent your toilet from wasting water. It could also point to one of these issues:

• Your fill valve is faulty.

• The float in the toilet tank is set too high.

• The chain that connects to the toilet handle is too tight.

How to Fix It

First, remove the lid from the tank and check if the float is higher than the fill valve. If so, then adjusting the float should fix the issue. 

If that doesn’t fix the problem, look at the chain. It might be too tight, preventing the flapper from sealing the hole properly. There may also be too much slack, causing the chain to tangle. 

If you notice any of these issues, try adjusting the chain by removing its clip to the toilet handle and increasing or decreasing the length. 

Not having any luck with these fixes? There might be parts that require replacement. Call in a plumber to give a proper diagnosis.

6. Toilet Makes Bubbling or Gurgling Sound

If your toilet is gurgling, the source of the sound can be tricky to trace and remedy without serious plumbing experience. Several issues could be causing the gurgle:

• A blocked sewer drain

• A blocked vent stack

• A blockage in the toilet itself

How to Fix It

Do not attempt to fix a gurgling toilet on your own unless you have significant plumbing experience. Avoid using the toilet, shut off the water supply, and hire a professional plumber as soon as possible. This method is the best way to keep the problem from developing into a more serious plumbing issue.

What to Do About Noisy Pipes When Flushing the Toilet

Luckily, a noise from your pipes when the toilet flushes isn’t always a death rattle. Many of these issues are repairable by fixing or replacing small parts. However, if there are issues with leaking, efficient water use, or broken components, these are good reasons to replace your toilet. Get in touch with a professional plumber to learn your options.

When to Replace Your Toilet

Most toilets have a life span of about 25 years, but the following signs may indicate it’s time to replace sooner:

• You have to call your plumber more than once to repair it

• The toilet clogs constantly or never stops running

• You notice cracks forming on the toilet's base or the lower part of the tank

• You need to flush multiple times after using the toilet once

• The toilet doesn't flush at all

If you aren't sure about the severity of your issues, have a local plumber diagnose the problem. They'll let you know if the toilet needs to be replaced or just repaired.

DIY vs. Hiring a Pro

Many toilet issues, including those listed above, can be solved with a quick fix that most homeowners can handle independently. Diagnosing the problem might take longer than fixing it. Other issues are so complicated, however, that a layperson can’t fix them and may cause more significant damage trying to do so. In those instances, it’s best to call the pros.

Cost to Fix a Toilet 

It’s always good news if you can remedy a broken toilet DIY. That usually means the repair is easier and cheaper. The cost could be as low as buying a $10 toilet flapper. 

If you’re unable to fix the toilet on your own, it indicates a more complex and, unfortunately, pricier issue. The average cost to fix a toilet when a professional is involved is $262 with a common range between $150 and $375.