Why Do My Pipes Squeal?

Hot Water Pipes

• When you hear your home's pipes squeal only when you turn on the hot water in a faucet, you can be sure that the flow of hot water in the pipes is the source of the noise. As hot water flows into water pipes, no matter what the pipes are made of, the pipes expand as they heat up from the sudden contact with the hot water. The sudden expansion of the pipes can cause the pipes to make noises as the fittings and pipes rub against each other, or as the pipes rub or vibrate against other objects inside the walls and under the cabinets of your house.

Pipe Straps

• Your pipes should be secured, even if they are behind walls or ceilings, with straps that are made of metal or plastic. Straps holding the pipes in place keep them from contacting wall studs or floor joists as well as other objects near the pipes. If the straps break or the mounting screws that anchor the pipes to the house’s framing come free, the pipes can begin making noises. Replacing the straps that have broken can help reduce or eliminate any noise coming from the pipes.

Water Hammer

• Water hammer happens when a valve in your house’s plumbing suddenly closes, stopping the flow of water suddenly. When the water stops suddenly, it sends shock waves of energy through the pipes. Water hammer may sound like the pipes knocking hard, or it may also sound like squealing or other noises when you shut off the flow of water running through a plumbing fixture. You can eliminate water hammer by closing the house’s main water valve, then opening the lowest-lying water valve in your house to drain all of the water out of the plumbing. You must close the water valve as soon as the flow of water stops, then open the house’s main water valve.

Damage Potential

• When your house’s water supply pipes make noises such as squealing, the noises are not usually indications of a serious problem with the pipes. In some cases, though, squealing from the pipes is a symptom of the pipe connections coming loose. Look for signs of water leaking in areas where you can hear the pipes squealing, including peeling or bubbling paint on the walls or ceiling. If you see water damage, you need to repair or replace the pipes to stop the leaking.