What Is A Water Hammer In Plumbing?

Last Updated On May 24, 2024

Updated on March 17, 2023



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What Is A Water Hammer In Plumbing

Did you hear someone refer to a water hammer when talking about your plumbing system? If you notice a loud banging noise when you turned on your faucet, you may have experienced a water hammer. 

This is a common plumbing issue with numerous possible causes. In this blog post, we will discuss what causes water hammers, how to resolve them, and some preventative measures that you can take to avoid them altogether.

In this PlumbingNav guide, we will cover:

  • What is a water hammer?
  • What causes a water hammer
  • How to resolve a water hammer?
  • How to prevent a water hammer

What's In This Guide?

      What is a Water Hammer?

      A water hammer is a hydraulic shock caused by a valve that closes too quickly. It transfers through your home’s water with no place to go. You can identify a water hammer due to the noisy pipes.

      The quick-closing valve interrupts the regular momentum of your water flow at a specific appliance, which creates a shock wave of pressure. 

      When pressure levels reach excessive levels, it can damage pipes and fittings. The shock can also cause the pipes to shake and hit nearby items, such as walls, causing damage that can lead to a burst pipe.

      The noise coming from your plumbing pipes can also create a nuisance, similar to other weird sounds that pipes can produce.

      Watch the video below for more information about water hammers:

      What Causes a Water Hammer Problem?

      Learn the causes of water hammer issues to help you diagnose and resolve the problem yourself!

      Plumbing Valve Closing Too Quickly

      A variety of things can cause a water hammer effect, but most commonly, it is caused by a sudden change in the velocity of the water due to a quick-closing valve or abruptly powered down pump.

      Faucets, dishwashers, washing machines, and even your ice machine all require a quick close valve, also known as a Solenoid valve or an electronic snap-action valve. 

      Your water heater’s shut off valve also uses a quick-closing valve. You may also use a quick closing valve for your emergency shut-off valve to your home.

      Main water supply shut off valves must adhere to the following plumbing requirements:

      • Closes all the valves
      • Operates at a single control in at least two remote locations 
      • Contains elements that melt between 208 °F and 220  and activate the emergency shut-down system.

      If your valve worked perfectly up until recently, it may have corrosion causing it to get stuck or move more suddenly. Copper pipe and copper fittings don’t corrode as quickly as other metals. Plastic won’t corrode at all, but they won’t provide the same longevity.

      Did You Know? Johannes von Kries first came up with the idea of a water hammer in 1898. 

      Loose Pipe

      If a water pipe in your walls becomes loose or a plumbing pipe becomes loose at the pipe joints, you may hear a noise similar to a water hammer caused by the pipes moving and bumping into things. Eventually, this can damage the valve. 

      Loose pipes will experience more damage since they must withstand the shock waves as well as trauma endured as they bang into each other.

      High Water Pressure Levels

      Most city codes require residential buildings to keep water pressure levels at 60 psi or lower. Some people may increase the water pressure not knowing the damage that change may cause.

      did you know water hammer arrestor

      How to Fix a Water Hammer (4 Step Guide)

      Use this 4 step guide to fix water hammer issues in your residential plumbing system. 

      Step One: Find the Source of the Noise

      First, try to locate the source of the noise. If it is coming from a faucet, simply turn it off slowly to allow the water pressure to equalize. 

      If the noise is coming from your washing machine, you may need to adjust the water level.

      If the noise is coming from your toilet and sounds like a whistle, it is probably due to a loose-fill valve. Simply tighten the valve until the noise stops, or replace it. 

      Step Two: Flush Your Plumbing System

      If alterations to the fixture or appliance in question didn’t resolve the issue, you may benefit from flushing your plumbing system. 

      Shut off water to your home at your main shut-off valve. 

      Starting on the top floor, open the cold water to your faucets and flush your toilets. Leave the faucets open for about 30 minutes before restoring water to see if that resolved the problem. 

      Step Three: Install Water Hammer Arrestor 

      Most faucets and appliances already have a water arrestor when you first get it installed. However, you may want to install a new water hammer arrestor if the old one somehow stops working. Here are some options

      Most water hammer arrestors work by using a piston or air chamber to act as a shock absorber. Pistons tend to produce better results than air chambers.

      You can install a water hammer arrestor yourself if you feel comfortable with your plumbing DIY skills, or you can call for a professional plumbing service.

      See this post for a review of the best water hammer arrestors.

      Step Four: Install Water Pressure Regulator

      Excessive water pressure may be the cause of your water hammer issue. Ensure the water entering your home won’t exceed proper pressure levels by installing a pressure-reducing valve that will make it easy to keep your water pressure at an appropriate level.

      Frequently Asked Questions About Water Hammers

      Why have I suddenly got a water hammer?

      You most likely suddenly experienced a water hammer due to a valve closing too quickly or a water hammer arrestor getting damaged. 

      How do plumbers fix a water hammer?

      Plumbers can fix a water hammer by flushing your plumbing system. This includes turning off water to the home, running the cold water for 20 – 30 minutes, and flushing all toilets before restoring the water. 

      If that didn’t work, the plumber might install a new water hammer arrestor.

      You should not need emergency plumbing to resolve a water hammer if you address the situation right away. 

      Is a water hammer serious?

      While you may not notice the damage right away, water hammers can cause plumbing issues. The shock waves create pressure. If pressure levels get too high, it can damage your plumbing material. Furthermore, the shock wave can cause the pipes to shake and bang into other items, causing damage.

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      About Plumbing Navigator

      We write about "all things plumbing," helping you navigate common questions, repairs, and the best plumbing products on the market.

      About Plumbing Navigator

      We write about “all things plumbing,” helping you navigate common questions, repairs, and the best plumbing products on the market.

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