Noise in Water Pipes When Flushing Toilet

Jump to Section

Banging pipes after you've flushed the toilet is a common problem that's very common. However, this banging noise is a symptom of a bigger problem. If you don't address the issue, it can cause damage to your plumbing and lead to some expensive repairs down the road.

Understanding why this noise occurs and knowing what you can do is critical to protecting your plumbing and keeping those pesky noises at bay. Here are some of the causes of banging noise in your toilet pipes and the solutions to fix it.

The Water Hammer Effect

One of the most common reasons for banging noises in toilet pipes is the water hammer effect. This happens when water suddenly stops or changes direction. You'll experience a loud bang in your pipes after a fill valve shuts off. When this happens, the energy from the moving water creates a shockwave that causes the pipes to vibrate and bang. This incident causes the excess water to hit the walls of your pipes at high speed, resulting in a ratting or hammering sound.

The Water Hammer Effect
Image credit:

This usually happens when you flush the toilet because of the sudden change in water pressure and direction. The water has to suddenly stop flowing in order to fill up the tank again, and this sudden stop creates the water hammer effect.

There are several ways you can fix this before you think of replacing them with the best flushing toilet on the market. Your pipes should all contain air-filled chambers that act as shock absorbers in each corner. If these chambers become filled with water, make sure you clear them out before air chambers work again.

You can usually fix this problem by installing a water hammer arrestor, a pipe-like installation that you can try to install yourself, or having a plumber install it for you. This is a device that absorbs the shock from the water, so it doesn't cause the pipes to vibrate.

The Problem with the Toilet Valve

The toilet valve is located at the back of the tank and is the part that allows water to flow into the bowl. If your toilet makes an alarming foghorn sound when you flush it, then it has a metal ballcock fill valve. The valve consists of a rubber washer that covers a metal seat. The purpose of the toilet's fill valve is to refill the toilet with water once you've flushed it. Over time, the washer can become hard and brittle, which will cause it to stop sealing properly.

The Problem with the Toilet Valve
Image credit:

This can cause water to slowly leak past the valve and into the bowl, which will eventually lead to a weak flush. In some cases, the valve may become so worn that it will no longer close properly, which can cause a constant drip. If you have a toilet that is constantly running, it is likely due to a problem with the valve.

As the water in the toilet tank fills up, it lifts the float on the valve until the float raises enough to stop the water flow into the tank. It does this by pressure on a small diaphragm within the fill valve, forming a seal. Over time, the diaphragm can harden.

When it loses its elasticity, this reduces its effectiveness at forming the seal. So, the vibrations you hear are the incoming water causing the hardened diaphragm to bounce around inside the fill valve. The best way to confirm if the fill valve is the problem, remove the tank lid and gently lift the arm of the fill valve. If the noise stops, then this is the culprit.

To fix this, try to replace the diaphragm within the fill valve, but fill valves are cheap enough that you might consider replacing the entire fill valve yourself or leave it to professionals.

A Worn Out Flapper

The flapper is the rubber disk at the bottom of the tank that lifts to allow water to flow into the bowl when you flush. When it's time to close, the flapper falls back into place and seals off the hole.

A worn out flapper is usually the cause of a phantom flush. This can lead to vibrating pipes when flushing your toilet. When the tank refills, it creates the vibrating noise you hear. This happens when you see the water in the bowl drop, but you don't flush. The flapper is not sealing the hole properly, and water is slowly seeping into the bowl.

FAQs on Why There is Noise in Water Pipes When Flushing Your Toilet

Loud bang when flushing toilet. Why?

You may have a high-pressure flush valve. If the water pressure in your home is over 80 psi (pounds per square inch), the high pressure can cause the fill valve to slam shut when it's time to stop filling the tank. This sudden stop can create a loud banging noise.

How can you fix noises in your water toilet water pipes?

If you have a worn-out flapper, you'll need to replace it. If your fill valve needs to be replaced, you'll need to call a plumber. Any time you're carrying out a bathroom renovation, make sure you check on your entire plumbing to be sure everything is okay. 

Final Thought on Water Pipes Making Noise When Flushing Toilet

Fortunately, a noise from your pipes when your toilet flushes shouldn't scare you. You can easily repair some of these issues on your own, but if you're not confident, don't hesitate to call in a professional plumber to help you out.


Ryan Copley

Ryan Copley

Having spent years participating in bathroom, kitchen, and home renovations, Ryan uses this experience to write informative blog posts on a wide variety of home renovation and kitchen topics.

Related Articles

Download Free Chart Now!

Your email will be used only to confirm your request and to provide free kitchen information. By submitting your info on this form, you are agreeing to be contacted regarding your service request by means of email. This is no obligation form and doesn’t require you to purchase any service.