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Why Do My Plumbing Pipes Make A Knocking Noise?

9/2/2022

shut off valve

Loud noises coming from plumbing pipes could be a sign of a serious problem. Here are the top three causes of banging plumbing pipe sounds: Water hammer, expanding/contracting copper pipes, and water pressure that is too high. Knocking sounds are often heard after a water supply is shut off, while the water is running or randomly throughout the day or night.

1. Water Hammer

Water hammer is a pressure surge, or high-pressure burst of water that stops or changes direction very quickly. The rushing water has nowhere to go and it can jar valves and pipe connections. It may not sound like a big deal but a water hammer can potentially damage valves and joints, which can eventually cause leaks.

To address the water hammering, you’ll need a plumbing expert at Service Legends to inspect all visible piping while the noise is present to see if there are any loose or vibrating parts that need securing.

Next, a plumber will need to check the air chamber. The air chamber is the vertical pipe located near your faucet and is often in the wall cavity that holds the plumbing connected to your sink or tub. The purpose of the chamber is to absorb the shock of fast-moving water that is suddenly stopped. Unfortunately, over time it loses its effectiveness and it will need to be replenished. To do that, turn off the water supply to your house. Open the faucets to drain out any water. Then turn the water supply back on. The incoming water will flush the air out of the pipes but not out of the air chamber. The air supply will then be restored to your air chamber.

2. Copper Pipes

You may also hear banging sounds coming from your plumbing if your home has copper pipes. Copper pipes tend to expand as hot water passes through them. If these pipes are in a tight area, they will expand and noisily rub against other structural features.

In most cases, expanding and contracting copper pipes will not cause a leak. Unless you are remodeling, there’s no reason to add additional padding around these pipes. The simple solution would be to slightly lower the water temperature setting on your hot water heater.

3. Water Pressure

Another reason for banging water pipes is that the water pressure is too high. Most modern homes have pressure regulators that mount where the water supply enters the house.

You may consider having one installed if your home doesn’t have one. Too much water pressure could damage any water-supplied appliances like your washing machine or dishwasher. It’s recommended that water is delivered to your home at no lower than 40 and no greater than 80 psi (pounds per square inch). You may need to hire a plumber at Service Legends to determine if your piping system is designed correctly if pressure issues persist.

If you’re trying to determine the source of your plumbing noises, make note of the time of day, and if any appliances are running (e.g. dishwasher, sprinklers, refrigerator, washer). If you can narrow down the location of the pipes involved, repairing the issue will be easier and less costly in the long run.

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