Understanding water hammer arrestors

Hammer arrestors help solve current and potential water hammer problems by silencing banging pipes and absorbing the shock after a change in water flow. When water flows through pipes at a pressure of around 60 to 70 psi (pounds per square inch), it carries energy that needs to be dissipated when the faucet is closed abruptly. This sudden stoppage creates a phenomenon known as a water hammer, which can cause pipes to shake or bang against walls.

Oatey offers Hammer Arrestors for multiple or single fixture installations ranging in sizes from AA through F. Oatey Hammer Arrestors accommodate pipe connections that include CPVC, 1807 PEX, 1960 PEX (Uponor), copper (sweat and press), male iron pipe, and compression applications. Oatey Hammer Arrestors are gas-filled and can be installed at any angle without affecting performance.

It’s important to note that water hammer arrestors require properly secured pipes. The arrestor may only partially absorb the energy if the surrounding water supply pipe is not rigid and securely fastened. Loose pipes will still allow energy dissipation, resulting in shaking and potential damage. Proper pipe support, like insulators and securing pipes through studs, is crucial to ensure the energy is directed towards the arrestor and not transmitted through loose pipe sections.

Ensuring the entire water supply pipe is securely fastened is essential for the arrestor to function effectively. Understanding how water hammer arrestors work and their applications can help ensure safe and efficient plumbing operations.

What water hammer arrestor works best for my application?

Water hammer arrestors, like Oatey's Quiet Pipes, create space for the water to move when there is a shock but feature a piston design in a sealed pressurized chamber to prevent water from remaining in the arrestor. This design also allows the water hammer arrestors to be installed at any angle and absorb shock. 

The internal piston creates a watertight/airtight seal to avoid any air loss and prevent the chamber from filling with water. Quiet Pipes come in nine connection types, including MIP, CPVC, PEX, and more.

Check out our project guide to learn How to Install Hammer Arrestors to Silence Banging Pipes.


If water hammer is left untreated, they can lead to various issues that range from minor annoyances to significant damages. One of the worst-case scenarios is the potential for leaks. 

If there are any weaknesses in the joints of the water system, whether due to improper soldering or incomplete installation steps, the repeated force of the water hammer can cause joints to blow apart. This can result in a wide-open water pipe and extensive water damage in your house.

Regular maintenance, proper installation, and water hammer arrestors can help prevent these problems and ensure the longevity and integrity of the water supply system.

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