Why Does My Water Faucet Make a Banging Noise When I Turn It Off?

water hammer when your pipes bang after turning off your faucetWith cozy fall weather upon us and holidays fast approaching, you’re likely to be spending a lot more time in the kitchen. A brisk day exploring the Roseville Floating Pumpkin Patch with the family or perusing the Farmer’s Market for tasty seasonal goods is enough to inspire anyone to start some baking. Soon, you’re surrounded by soap suds and dishes that need washing. Then, as you turn off the faucet, you hear it—that loud, horrible banging sound.

Halloween may be coming up, but that booming sound from your walls is not a monster—it’s a condition known as water hammer, and it happens when water tumbles and churns around in piping instead of flowing evenly. While water hammer is a common issue, the loud noise is still a nasty surprise. If you are hearing it in the kitchen, you might also hear it in other parts of your home where there’s piping, such as your laundry room. The good news is, it can be easily fixed with just a little knowledge and a little elbow grease, be it from you or your local plumbing expert.

What Is Water Hammer—and Why Is It So Bad?

Water hammer happens because water begins churning when a valve—usually the one that is part of your faucet—is closed, causing a spike of pressure in the form of air. This air is quickly forced into your piping and agitates the water, which creates the loud racket. If left alone over time, the pressure can cause the pipes to loosen from the brackets attaching them to the inside of your walls, and can even create leaking in the joints of the piping. But, maybe luckily, the noise from water hammer is hard to ignore, and, if addressed quickly, it can be corrected relatively easily and inexpensively.

The Reason Your Pipes Have Water Hammer

So you hear all that horrible banging and think, why did that just start happening today? The truth is, air leaking into pipes is unavoidable, and it usually occurs over time.The three factors that contribute to water hammer are:

  • The size and length of pipes: As a rule, the longer a piping run is, the larger the piping needs to be. So if the piping size and length are not proportional to the expected water pressure, then it can create excessive pressure, which in turn creates water hammer.
  • The time it takes for a valve to close: A piping valve that closes quickly is more likely to create water hammer, because the abrupt closure of the valve forces air into the piping.
  • The velocity of water in pipes: Water hammer increases with the speed of the water in your pipes. This is because the velocity of the water creates a greater force in the piping, which causes the banging and clanging noises. Because of this, many solutions to water hammer center around slowing the speed of the water.

Getting Rid of Water Hammer

Controlling water hammer may depend on when your home was built. Older homes had a form of water hammer protection, while some newer homes have none at all. Here’s what you can do depending on when your home was built:

  • Before 1960: Homes built before 1960 typically have an air chamber built into the piping. This chamber featured a pipe which connected to your water piping with a T-shaped fitting. The other end of the pipe was capped off, and this end is where the air would be pushed, thus preventing water hammer. These pipes are rendered useless if they get filled with water, but this problem can be fixed by flushing out the air chamber. This requires turning off the water supply and then draining all the water from your pipes.
  • Between 1970 and 1990: During these two decades, most home plumbing was not configured with water hammer arrestors. Homes like these simply need to have one installed by a certified plumbing professional.
  • After 1990: Almost all homes built after 1990 were built with water hammer arrestors in the piping. This is a spring loaded device that absorbs the shock from the air pressure but does not absorb water like older air chambers. If you have a newer home with an arrestor installed but are still experiencing water hammer, you may need to have yours checked for malfunctions. Otherwise, you might have some other issue with your piping such as high water pressure.

Diagnosing water hammer in your home depends largely on when your home was built, but if you are sure that turning your faucets off is causing those clanging sounds, you should contact a plumbing expert. It might be as simple as flushing out your pipes, but air chambers sometimes fail and need to be replaced with air arrestors. Or it might be a scenario in which air arrestors were never installed in the first place. In both cases, the best solution is to have them installed as quickly as possible to avoid any piping damage.

Cooking up some pies or toasting some pumpkin seeds is a great way to ring in the fall season here in Roseville, so don’t let those scary banging sounds in your pipes make you too afraid to have some fun. Once you recognize the sounds of water hammer, you can easily decide whether or not you need to flush out your pipes or have your water hammer arrestor examined.

If your pipes are banging (and you’ve ruled out ghosts) contact the experts at Bell Brothers to help with your loud pipes or to install a water hammer arrestor. We’ve been trusted plumbing professionals in the Roseville area for over 25 years.