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Water Pipes Knocking: Everything Homeowners Should Know

plumber inspecting water pipes knocking

Do you hear loud, strange noises like a banging and knocking sound near your water pipes in your home?

There is nothing more frustrating than having water pipes knocking in your home. You put up with it for a while, but if the noise doesn't get any less frequent or intense, it will eventually get to you and there's no way around it.

Water pipes can knock for a variety of reasons and knowing what to do when they start will allow you to get them fixed quickly by reliable plumbing services before any serious damage occurs. If water pipes are knocking in your walls, something needs to be done about it; here's what you need to know!

Know What Causes Water Pipes Knocking Before You Fix It

There are several reasons causing a loud knocking sound within your plumbing pipes which is why understanding the possible causes will help you determine if there's an underlying issue or not - and what it could be. The knocking noise is caused by the expansion and contraction of water within the metal or plastic pipes in your house. When water runs through a pipe it heats up or cools down, causing it to expand or contract.

Water Hammer

The process is called water hammer because the sound that results from these changes closely resembles a beating drum. While this happens in all homes with running water, some houses are more prone to experiencing it based on where the water pipes are located, how old they are and what type of pipes are being used.

When you hear a noise only when you stop a flow of water - and not when the water runs - then your pipes could have problems. Home constructions prior to 1960 typically feature air chambers. Air chambers can be defined as tubes in tubes in T-shapes which contain air. However, water can move air from a chamber over time.

If you have air chambers, you can remove the water from the plumbing and fill the water with it. Homes that were built in 1960 should be fitted with water hammer arrestors. These water hammer arrestors are the new alternative to air chambers. The system uses springs, but it rarely fails.

There are other issues that could be at play within your home's plumbing system, including:

High Water Pressure

High water pressure is one of most common causes of water pipes knocking. In situations where water pressure is too strong the pipe could shake despite being secured in place on the walls. If it was true then you will be able to tell when the sounds originate only when the water is running. Nevertheless, the sound is usually a quiet tapping sound, not a complete knock.

For example, if someone has just used a water hose in the backyard it means there is more water rushing through the pipes, which can cause a build up of energy - this sudden rush of water also has nowhere to go. Sometimes that excess energy will find its way into other parts of the house's plumbing system and manifest itself as knocking noises coming from your water pipes.

Your water pressure is between 60 to 80 PSI. Typically, cold water pressures are higher than 80 psi, and a pressure reducer will be required. Using hot water may help lower the temperature slightly. If it fails, consider adding a heat expansion tank. It absorbs pressure and provides protection for your pipes.

Loose Supply Pipes

Using the water supply pipes in your bathroom can become loose with time. The flow of water through the loose pipes can cause them to hit their walls and it's like a noise you get when you knock. Problems happen only if the water runs, and if the banging noise stops when shutting down water, it's a good indication there's a leakage.

When supply pipes are loose they can start shaking, hitting against other objects in your home, or even banging together creating a water hammer effect which might sound like knocking in your home's water pipes.

When the pipe can be reached, you should be careful not to tighten it too tight so that it expands or contracts due to changes to water temperature.

Are Knocking Pipes a Serious Problem?

Although it might be an annoyance to hear loud banging sounds coming from your home's pipes every so often, you should never ignore water hammer. Noises that come from running or stopping water are typically only temporary problems that will subside after one or two weeks.

However, ongoing knocking sounds keep happening regardless of whether water is flowing through the pipes or not indicate that there is something wrong with the way your home's plumbing is designed. This could lead to some plumbing service repairs or even replacement down the line if left unresolved for too long.

Some signs that you may need your water pipes looked at by expert plumbers include:

  • Drinking faucets or toilet flushing producing a loud banging sound
  • Creaking noises when turning on a water supply
  • A hissing noise from the pipes while waiting for hot water to reach its destination
  • Noises heard while hot water is running somewhere in the house
  • Noises heard after a cold or hot water supply is shut off
  • Noises heard while cold water is running
  • Banking pipes heard randomly throughout the day or night

How Can I Fix My Knocking Water Pipes?

In many cases knocking pipes are simply due to loose elbows or valves that aren't completely open or closed around your home. In some instances, the base of the pipe may be vibrating against another surface because of air pockets in between them. If these causes don't work, you might need new plumbing installed. Fortunately, most of these problems can be fixed without calling a plumber.

Check Your Valves

If the banging sound is coming from a water supply pipe, make sure that all valves and faucets are fully open. If this doesn't solve the problem, try turning up the water pressure in your house by adjusting the main valve to your property. This will often get rid of excess bubbling or gurgling noises between air chambers that result from low water flow rates.

In some cases you may have to replace worn out pipes found on exterior walls where they're exposed to severe temperatures changes throughout the year. For clanging sounds whenever water starts running through a pipe anywhere around your home, check for loose valves or elbow fittings and tighten them back down or completely replace them if necessary. Painting over old rust spots on internal pipes can also stop random noises from water hammer.

Check Your Water Heater

Sediment buildup in your water heater is the most common reason for inexplicable banging noises when there's no water running. It may be loud enough that the echoes carry and cause it to seem like the knocking noise is coming from the pipes in the wall.

The noise is the steam bubbles escaping from the accumulated sediment at the bottom of the water heater tank. It's similar to how, when you boil water in a covered pot on the stove, it begins pushing up against the lid. Flushing your water heater can help rid of these noises if water isn't running.

Need Your Plumbing Pipes Checked by Expert Plumbers?

Want to get rid of that knocking sound for good? Call the national home service experts at ARS/Rescue Rooter. We have certified plumbers standing by to restore your home's plumbing system to pristine condition.

Call our plumbers at 866-399-2885 or find your nearest ARS/Rescue Rooter location to schedule service today!

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