How to Handle Water Hammer

The annoying sound of water hammer can be more than just an inconvenience. Learn what to do about water hammer before your plumbing is damaged.

Instructions

  • Step 1: Install a water hammer arrester behind the valve or faucet that is causing the water hammer. A water hammer arrester is an air-filled tube that connects to the supply pipe. It allows the pressure in the pipe to dissipate into the air instead of exploding in the pipe.
  • TIP: Arresters may be difficult to install if the problem pipe is inside a wall to supply a dishwasher or refrigerator.
  • Step 2: Change all of your fixtures -- or at least the offending one -- to a low-flow fixture. Low-flow fixtures use less pressure, so the flow of water to the valve won't be fast enough to cause water hammer.
  • FACT: Hollowed-out logs were used as water pipes in America in the late 1700s to early 1800s.
  • Step 3: Install an expansion tank, which contains a rubber diaphragm that cushions the shock wave of water hammer.
  • Step 4: Secure your pipes -- especially along particularly long, straight runs -- to reduce water hammer. Copper water pipes should be strapped to ceiling joists at 4-foot intervals to reduce rattling.
  • TIP: You can check your home's water pressure with a gauge available at hardware stores.
  • Step 5: Replace the pipes leading to the valve. If you increase the size from your 1/2-inch copper supply pipes to 3/4-inch pipes, the water velocity will slow and the chances of experiencing water hammer will be greatly reduced.
  • Step 6: If your water pressure is excessively high -- between 60 and 80 pounds per square inch, or PSI -- you can install a pressure regulator to decrease the pressure. If you reduce the pressure to between 40 and 50 PSI, you will still have sufficient water pressure in your plumbing.
  • Step 7: Reduce the pressure in your pipes. Water hammer occurs when water traveling at a high rate of speed is suddenly stopped, usually by closing a valve or faucet. If the pressure is reduced, the water's velocity will slow, and the shock wave caused by closing the valve won't be large enough to cause a noise.

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