How to Reduce Water Hammer in a PVC Pipe

Water under high pressure inside a pipe flows at high speed towards an open faucet or outlet. Shutting off a faucet abruptly sometimes creates an air pocket and a resulting phenomenon known as a water hammer, which is caused by the sudden change in water pressure. Water hammer makes a lot of noise, causes pipes to vibrate and damages fittings. Water hammer is a common problem in households, but it can be eliminated by installing a water hammer arrester.

Water hammer can be hard on the pipes and ears.

Step 1

Locate the main shut off valve and turn off water supply to your home. Using a hacksaw, cut the PVC cold-water pipe to accept a PVC tee as close to the faucet or water-intake valve as possible. Using a utility knife, smooth the tip of each pipe.

Step 2

Attach the tee fitting temporarily to the pipes, and align the tee so that the opening points straight upwards. Mark a horizontal line across the pipe and fitting using a felt pen. The line will serve as your guide to quickly reassemble and align the pieces after you have applied the solvent cement. Now, remove the fitting. Clean the tee fitting and water pipes with pipe cleaner and add primer, according to manufacturer's instructions.

Step 3

Apply solvent cement to the tee and pipes and attach the fitting to the pipes. Distribute the cement by twisting the tee slightly clockwise and counterclockwise, and align the marks you made earlier. Hold the pieces together for a few minutes to allow the solvent cement to set.

Step 4

Weld a 2-inch PVC nipple on top of the tee using solvent cement. Allow a few minutes for the cement to set, then weld a reducing female adapter to the nipple. Install the threaded end of the water hammer arrester by hand into the reducing female adapter. Tighten the arrester using two wrenches -- one wrench on the adapter and another on the arrester.

Step 5

Install another water arrester on the hot-water pipe following the same procedures used to install the arrester on the cold-water pipe. Read the solvent manufacturer's instructions to know the length of time needed for the solvent to cure before opening the main water valve.