How Can I Stop Banging Water Pipes?

Is the Plumbing in My Home Haunted? 

While there are plenty of spooky places to visit in Minnesota, your house is the last place you want a ghost or a member of the undead. Loud banging water pipes when you turn on your washing machine or flush your toilet are annoying. Is there something living in the walls or worse, is your plumbing possessed?

That sound is called a “water hammer,” and it can be frustrating (to say the least).

Figuring out why a water hammer happens is you ghost holding banging water pipes

The Cause of Banging Water Pipes in Your Home

What Is A Water Hammer?

 When you flush a toilet, water runs through the pipes, but as the toilet finishes filling up, a valve closes, causing the water to crash against the lid. This creates loud noises and vibrations and in some cases, causes the pipes to bang against the wall (which is where the water hammer name comes from).

How Do You Fix A Water Hammer?

First, you need to know when your house was built.

Homes built before 1960s:

Older homes built before the 1960’s were made with air chambers to prevent water hammer. The air chambers are merely T-sections of pipes that contain air and act as shock absorbers.

These air chambers can eventually become filled with water, leading to water hammer.


  1. Turn off the water supply to your home.
  2. Drain all the water from your home’s pipes (i.e., faucets, toilets, dishwasher, etc.).
  3. Turn the water back on.

Homes built since the 1960s:

Modern homes are built with water hammer arrestors, instead of air chambers. These devices are connected to your pipes and contain a spring-loaded shock absorber, diverting the water and reducing the loud noise.

These arrestors almost never become clogged with water, unlike air chambers, so if you hear loud noises, call a professional to come and check it out (it may turn out that your home never had a water hammer arrestor installed, to begin with).

Other Reasons Why Your Pipes Are Making Loud Noises

1. Does the knocking happen only while hot water is running?

Some houses use CPVC (chlorinated polyvinyl-chloride) as their hot water supply pipes. If a CPVC line were routed through an area that is too tight, you’d hear rubbing or knocking noises anytime hot water runs through that pipe.

Why? Because CPVC piping will expand when hot water runs through it. The only way to fix this is to call a professional plumber to relocate the pipeline to fit your home better.

2. Does the sound happen while cold water is on or running?

If this is the case, then high water pressure is creating the knocking noises you hear. This is because when the water’s flow rate is above a certain level, the flow goes from even to chaotic. In other words, when water is flowing at an extremely high rate through your pipes, it’s going to create a lot of noise.

You can test your home’s water pressure with a water pressure test gauge. If it’s too high, you’ll need a professional technician to add or replace your PRV (pressure-reducing valve).

Dean’s Home Services won’t be able to help you with a ghost BUT if you hear loud noises coming from your water pipes, Dean’s Twin Cities area Plumbers are here to help! Dean’s Home Services has been plumbing Minneapolis and the surrounding Twin Cities metro for over 25 years, we can fix whatever plumbing issue your home may face — no matter how big or how small.

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