How to Cure Water Hammer

Water hammer is a loud hammer noise that radiates from plumbing. It occurs when there is a sudden change in water pressure. The change in pressure occurs most dramatically when plumbing fixtures are turned off, such as when a toilet completes filling or a faucet is turned off quickly.

Plumbing pipes.

It is inexpensive and easy to cure water hammer with the proper fitting, called a “water hammer arrester”; water hammer can be cured on any type of pipes. Choose a push-type fitting which does not require special tools, heat or glue and can be used with any type of plumbing.

  1. Create the water hammer noise by turning off the water supply at the location most frequently causing the noise in order to locate the section of pipe that is the source of the sound.

  2. Turn off the water supply from the main water source.

  3. Place rags on the floor and place a bucket under the section of pipe that will be removed to install the push-type water hammer arrester fitting.

  4. Cut the pipe with a hacksaw or pipe cutter. Hold a bucket under the opening to allow water from the pipes to drain into the bucket.

  5. Dry the ends of the pipe with a rag.

  6. Rub a sheet of emery cloth on the pipe ends to remove all burrs and rough spots. Rub gently with your finger to ensure all rough edges are smooth. Be careful--pipes can be sharp and quickly cut your finger.

  7. Press one side of the pipe onto the push-type water hammer arrester fitting with one quick, firm movement. Repeat for the other side.

  8. Turn on the water supply. Test the water hammer arrester for proper functioning. Attempt to create the water hammer noise by quickly turning off the water supply at the location most frequently causing the noise. A second water hammer arrester may be required at another location on the supply line.

  9. Tip

    Place a water hammer arrester on every section of line that branches off the main water line to be sure that water hammer cannot radiate from another section of plumbing.


    If the water hammer arrester will be located on a hot-water line, position the fitting as far away from the water heater as possible to reduce the risk of the hot water softening the gasket in the push-type fitting.