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2 possible causes of water-line bangs

Question: We have a noise like a backup of pressure in water pipes that occurs not only while using water but also at night when no one is using water. Sometimes it lasts for five or six seconds and is loud and annoying. It is a vibrating kind of sound.

We live where we have close neighbors in a subdivision and are on city water and sewer. Any information would be helpful since we have no idea who to talk to about this. It does not happen every time we use water.

Answer: Rattles and popping in water line pipes are caused usually by either air in the lines or by expansion and contraction of the hot water lines.

Air in the lines is only noticeable when the water is being used, and the noise occurs when a faucet is shut off. There is a loud sound like someone hitting the pipes with a hammer.

Expansion and contraction occurs in metal hot water lines and can sometimes be heard when the water is not being used because the water is still being heated by the water heater.

Adding air shocks to the water lines at the water heater will relieve the hammer noise. Installing foam strips between the water lines and their hangers can help reduce the popping noise.

Long water lines also present a problem with expansion and contraction. Also, have the plumber check to see if the long lines have room in their hangers to expand.

C. Dwight Barnett, a member of the American Society of Home Inspectors and a former contractor, was selected Great Lakes Chapter Inspector of the Year for 1991. Questions may be addressed to him c/o the Evansville Courier, P.O. Box 268, Evansville, Ind. 47702.