How to Quiet Noisy Water Pipes

A water hammer, loose mounting straps, or high water pressure can cause water pipes to clang and clatter. Never fear, here are tips for quieting your water pipes, no matter what is causing all that noise.

Combating water hammers

Imagine a fast-moving stream of water traveling down a narrow pipe. Suddenly and unexpectedly, the water finds a closed valve in place of what, moments earlier, was an escape point. All of a sudden, the water has nowhere to go. As it comes to an abrupt stop, a loud thud results, and it can be heard throughout the entire house. This deafening sound is known as a water hammer. The hammering action that creates the horrible racket is actually capable of damaging joints and connections in the pipe.

An air chamber is a vertical pipe located in the wall cavity at the point near a faucet or valve where the water-supply pipe exits the wall. Air chambers act as cushions to prevent water from slamming against the piping. Because air compresses, it absorbs the shock of the fast-moving water before it has a chance to slam against the end of the pipe. Many household plumbing systems have air chambers built into them at critical locations — like the clothes washer and dishwasher — where electric shut-off valves close rapidly. In some homes, air chambers exist at every location where water is turned on and off — even the toilet.

To eliminate a water hammer, you need to replenish all the air chambers with air. You can’t inspect the air chambers, so this procedure is a must whenever you notice a faint noise in the pipe:

  1. Shut off your home’s main water supply valve.

  2. Open the highest faucet inside your house.

  3. Find the lowest faucet on the property — it’s usually on the first floor somewhere outside or in the basement — and turn it on to completely drain all water from the pipes.

    As the water drains from the pipes, air automatically replaces it.

  4. The moment the water is completely drained from the piping, turn off the lowest faucet and reopen the main valve.

    Air pushes out of the horizontal and open vertical water lines, sputtering as it exits the faucets inside. However, air remains in the air chambers, eliminating water hammer.

Tightening loose mounting straps

Sometimes a water hammer can occur when a pipe-mounting strap is loose. These straps consist of metal plumber’s tape or the vinyl-coated nail-in hooks and hangers that attach pipes to framing. A loose pipe strap allows the pipe to freely vibrate against framing members as water is turned on and off. Check all accessible pipes to ensure that they’re properly and tightly connected.

Never use galvanized plumber’s tape or galvanized straps on copper pipe. When different metals contact one another, electrolysis can occur, which can lead to a plumbing leak.

Adjusting too-high water pressure

Another reason for banging pipes is excessively high water pressure. You can adjust water pressure with a water-pressure regulator or pressure-reducing valve. Most modern homes have a regulator mounted at the location where the main water supply enters the home.

If you don’t have a regulator, consider having one installed. A professionally installed pressure regulator can cost several hundred dollars, but it’s a good investment in the long run. (Only do-it-yourselfers with some serious plumbing skills should try to install a pressure regulator themselves.)

Not only is high water pressure wasteful, but it can damage dishwashers, icemakers, washing machines, and other water-supplied automatic appliances. In fact, many appliance warranties are voided when water pressure exceeds 100 pounds per square inch (psi).

Testing water pressure is important regardless of whether you have a pressure regulator. You can test the water pressure yourself using a water-pressure gauge that screws onto a hose bib; in most communities, the water department will conduct the test at no charge. Normal water pressure runs between 30 and 55 psi. If you already have a regulator, use a screwdriver or wrench to adjust it so that the pressure doesn’t exceed 50 psi.

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