Kitchen Faucet Probem
Q. Often when I turn off my kitchen faucet there is a sudden fierce banging. This also occurs after my washing machine has completely filled and the water shuts off. It’s very annoying. What is it, and is there something that I can do about it?
A. It sounds as if the condition which you are describing is a perfect example of what is called “water hammer.” This noise generally occurs when you turn off the water at a faucet or an appliance quickly. The water in the pipes slams to an abrupt stop, causing this hammering noise.
In some cases this could be caused by pipes that are loose or not properly anchored. The remedy here is quite simple. Just add some pipe straps or cushion the pipes at existing straps with rubber blankets, or both. Remember, never use galvanized straps on copper pipe – electrolysis will occur and break down the metal. The most common cause of water hammer is faulty or nonexistent air chambers.
These air chambers are constructed of small lengths of pipe installed in the wall behind fixtures and appliances. Air chambers are designed to hold air that cushions the shock when flowing water is shut off. However, they can get filled with water and lose their effectiveness. They can be restored by turning off the water supply at the main valve and draining the system at its lowest point, (this is generally the hose bib located at the point where the water enters the home). There are retro-fit air chambers that can be installed after the fact that don’t require tearing into the wall. See your local plumbing parts supplier for these very handy devices.
Another cause of water hammer is water pressure that’s in excess of 80 pounds per square inch. Most modern plumbing systems have a pressure regulating device at the main water inlet valve. If your home doesn’t have one and the pressure in your system is high, it would probably be a good idea to have one installed.