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Sweetwater Plumbing Blog

What Is “Water Hammer”?

woman-shocked-by-noiseNo, it’s not a magical item from a fantasy story—although that would be a neat weapon. Water hammer is the name for the loud thumping sound that may suddenly come from your home’s pipes. Water hammer is a common occurrence—in fact, in early plumbing systems, water hammer was what often caused people to believe their houses were haunted!

It’s not a ghost, so what is it?

What’s occurring when you hear water hammer is the abrupt stop and reversal of water flow in the pipes. This can happen when a faucet or other tap is shut off. The force of the water direction change creates a noticeable banging or thumping sound.

But I don’t hear this every time when I shut off a tap

No, and you shouldn’t. Residential plumbing is designed to cushion the water pressure whenever a tap closes. The plumbing contains air chambers that create a buffer for the water. If those air chambers are empty, water hammer will start to occur. Water hammer also occurs if the pressure in the pipes is too high.

Is water hammer something I should worry about?

If you only hear water hammer on a rare occasion, no. There can be slight pressure builds and declines inside the plumbing that aren’t serious problems. But if the water hammer is happening frequently, it’s something that needs to be remedied.

The trouble with water hammer is that force of the water can cause damage to the plumbing pipes. High pressure inside the pipes can harm them, even to the point of causing them to burst.

What can I do to stop water hammer?

You’ve already made the right first step: you’re on the website of a professional plumber! Our trained plumbers in Santa Ana, CA can find out the cause of the water hammer and find a way to fix it. This may require installing a water pressure regulator, restoring empty air chambers, or using mechanical water arrestors which contain a spring and an air bladder.

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