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Advanced Plumbing and Rooter Service

231 Market Place, Suite 540
San Ramon, CA 94583

Phone: 925-383-6100

C-36 License #782789

plumber repairing a u-pipe

How to Fix a Knocking Sound Coming From Plumbing

Do you have loud, knocking noises coming from your pipes and plumbing? Do you notice the knocking starting when you turn a faucet on or off or when you use a certain appliance in your home? While a knocking sound coming from your pipes can be annoying and disturbing, normally it has an easy fix. Paying attention to how and when knocking sounds occur can allow you to pinpoint and diagnose the cause of the sounds and apply the appropriate fix to stop the knocking sounds from your plumbing for good.

Knocking is Caused by Water Hammer

Water hammer occurs when a water supply is suddenly stopped, and the water flowing in the pipes ‘hammers’ against the closed valve. The resulting noise created can be very loud and disturbing. Turning the faucet off carefully may not allow you to avoid water hammer. It is easy to establish if the knocking sounds in your pipes are caused by water hammer. When affected by water hammer, you will hear the telltale banging of the pipes when you turn off your faucets or appliances.

How to Fix Water Hammer if Your Home was Built in the 1960’s or Prior

Finding the appropriate fix to water hammer in your pipes depends on the age of your plumbing. Older homes are often more likely to experience water hammer. Plumbing systems installed during or before the 1960’s used pipes that were installed with air pockets to act as shock absorbers and counteract water hammer. Unfortunately, the air pockets in the pipes can fill with water, causing them to lose their effectiveness.

Fortunately, there’s an easy fix for water hammer in these plumbing systems. Start by switching the water supply off at the main. Open all the faucets, flush the toilets and run all of the other water-using appliances like the dishwasher and washing machine. As a result, all of the water held in the pipes will be flushed out of the system and then water can be switched back on at the main.

How to Fix Water Hammer if Your Home was Built after the 1960’s

It is likely you already have water hammer arrestors installed if your plumbing system was installed after the 1960’s. Water hammer arrestors are effective and rarely fail, with little to no need for repair or replacement. The existence of water hammer in newer plumbing systems is usually a result of your system not being installed with arrestors and you may need to contact a local plumber to have them installed.

Knocking Caused by High Water Pressure

High water pressure causes pipes to vibrate more strongly and wildly than usual, causing the pipes to hit against the walls or each other. The knocking sound is particularly noticeable when water starts flowing, such as when a faucet is opened. Call a plumber to diagnose high water pressure, and correctly adjust the water pressure for your pipes. Generally, high water pressure can be remedied by installing a water pressure reducing valve on the main water inlet.

Knocking Is Due to Sediment in your Water Heater

Random knocking from your water system at random times throughout the day is usually caused by excess sediment in your water heater. You can flush this sediment out yourself, or call a local plumber to do it for you.