Why Do Pipes Make Noise?


You rely on the pipes in your plumbing system to bring water to all parts of your home when you need it, whether you’re doing laundry in the washing machine, baking in the kitchen, flushing the toilet, or relaxing in a hot bath. Unfortunately, pipes aren’t always in good working condition, and you may notice that some of them start to make seemingly random noises. If this is an issue you’ve experienced, read on to diagnose the cause and hopefully restore the quiet.

Why do pipes make noise?

  • If your pipes make a rattling or clunking noise, it could mean that they aren’t fitted correctly or they’ve come loose over time. As a result, the movement of water through them causes a disturbance.
  • If you have pipes made from copper, the movement of hot water through them will cause them to expand and contract which may make noise especially when the pipe rubs against brackets, joints, and support structures.
  • Noisy pipes may also be a result of a water hammer, which occurs when a closed valve suddenly puts a stop to the flow of running water.
  • Noise may also occur if the water pressure is too high – this will cause it to move through the pipe too quickly and result in a vibrating or crashing sound.
  • Sometimes you may notice your plumbing system may make a gurgling sound which could indicate a clogged passage in the piping.
  • If your pipes make a whistling sound with normal water flow, the issue may be a valve that creates its own vibration.

Pipes that are working normally should not make noise – domestic plumbing systems should be almost silent. To get to the root of why your pipes are making noise, you need to be aware of the most common causes. 

1. Your pipes are loosely fitted

Loose piping in your home can lead to clunking, vibrating, or rattling noises. A pipe allows for the flow of water around your home, and this movement can sometimes cause the pipe to move about and bang against objects and walls.

The first step to dealing with loose piping is to identify the source of the problem. If you can access the pipework, have someone else turn on a tap or flush the toilet to test. While doing this, you will need to be very keen and observant so that you can pinpoint the exact location. Once you find it, you can attempt to re-establish the appropriate fitting by tightening the bolts or replacing any fixtures that may be worn out.

You can also try adding a piece of foam or rubber pipe insulation to the pipe and strap it back into place using metal plumbers’ tape. Avoid using galvanized plumbers’ tape or galvanized straps on copper pipes as the metals can react with each other and cause further wear and tear. If you’re unable to access the pipe, wrap foam padding or insulation at the nearest accessible sections of the pipe. If this also fails to work, consider seeking professional help.

2. You have copper pipes

It’s common  to find pipework made from copper – its a durable, malleable material that has been used in place of steel and lead in modern homes. Pipes made from this metal are known to heat up and expand when hot water runs through them. In tight spaces, copper hot-water pipes can expand and rub against your home’s structural features (studs, support brackets, joists, etc.) as they contract.

A possible solution to noisy copper pipes is to turn the water heater temperature down slightly; sometimes a small adjustment in temperature can eliminate the issue and save you from having to ask a plumber to do invasive pipe work. If the pipes are easily accessible, they can be insulated with foam rubber to prevent friction. If the supply walls are drywalled in, you can have a professional install insulation.

3. Poor construction of CPVC pipes

Some homes use chlorinated polyvinyl-chloride (CPVC) water lines to supply their hot water. If a CPVC line is routed through an area or hole that is too tight, you’ll hear a clicking or knocking noise every time hot water runs through the pipe. Like copper, CPVC piping naturally expands when hot water runs through it. To accommodate this, a plumber should ensure that CPVC piping is constructed with plenty of free space around it to prevent friction.

4. The occurrence of water hammers

Sometimes the metal pipes in your plumbing system may bang loudly when you shut off a faucet suddenly, or when an appliance such as a dishwasher or washing machine shuts off its water intake abruptly. The phenomenon is commonly referred to as water hammer. The technical term for this occurrence is hydraulic shock, and it occurs when a water valve is shut off and water stops or is forced to change direction suddenly. The loud, thudding sound you hear is as a result of the shockwave caused by water banging against the shut-off valve or pipe walls. 

In addition to being startling and annoying, water hammer can sometimes be violent enough to break pipes or shake them loose of their joints. The following are the most common solutions to water hammer:

  • Secure loose pipes – Even a mild case of water hammer can create loud banging if your pipes are not secured properly. You can prevent this by tightening any loose pipe straps that secure the pipes to studs or joists. You can also wrap foam pipe insulation around your pipes to serve as shock absorbers. This is suitable for exposed, unfinished areas, such as a basement space where pipes are likely to be visible and accessible. 
  • Install an air chamber – Another option is to install a short segment of vertical pipe known as an air chamber near the valves causing the banging noise. That way, a segment of empty, air filled pipe is created, providing a cushion for water to flow into when it changes direction suddenly. 

You may already have an air chamber installed in your home, but another issue may come up – it becomes filled with water and stops functioning as it should. You can correct this by periodically draining your entire water supply system to restore air to the chambers. This can be done in the following steps:

  • Shut off the water supply to your home at the main water valve.
  • Open the uppermost water faucet.
  • Open the lowest faucet (it’s typically outside or in the basement) and allow all the water to drain out. As the water flows out, air will be refilled in the system through the uppermost faucet, subsequently restoring air in the chambers.
  • Turn off the lowest faucet and turn the main water valve back on. Leave the uppermost faucet on until water flows out its spout, then turn it off.
  • Install mechanical water shock arrestors – If air chambers aren’t an option, consider getting water arrestors installed. These are sealed units that contain a spring and air bladder that absorb water movement to alleviate the effects of water hammer. Unlike air chambers, mechanical water arresters don’t need to be recharged, and they only require replacement at the end of their life cycle. 

5. High water pressure

Water flowing at high pressure can create knocking noises. This is because when water flows through a pipe too fast, it begins to bounce off the sides as well as into itself, which shakes the pipe. The shaking pipes can in turn rattle against other pipes and the walls, making that annoying knocking noise you may hear.

Furthermore, high water not only puts your pipes at risk, but it can also lead to appliance breakdowns. If water is flowing into washing machines, dishwashers, and other water-reliant appliances at too high a pressure, it can damage their internal components. 

You may have a water pressure regulator – you’ll find it at the area where the main water supply enters the home. If you don’t have one, consider checking your water pressure yourself by buying a pressure gauge from your local DIY and home improvement store. Your water pressure should run between 40 and 60 psi. If it’s higher than 80 psi, you should adjust your water pressure regulator; if you don’t have one, you might want to call in a plumber to install it for you.

6. There may be sediment buildup

Random noises when there’s no water running may indicate sediment buildup in your water heater. The noise is due to steam bubbles escaping the sediment that has built up over the years at the bottom of your water heater tank. You can fix this problem by having a plumber flush your water heater to clear out the sediment.

7. A faulty shut-off valve

A whistling noise coming from your pipes could be an indicator of a bad valve in your plumbing system. To pinpoint the source of the sound, turn on your water faucets, one by one, to investigate. Once you find the source, remove the washer, valve, and valve seats. Rinse any grime that may have built up on the components, and replace any corroded parts. If this doesn’t solve the problem, you may need to have the valve replaced.

Final thoughts

It’s not always easy to pinpoint the exact cause of a noise in your pipes. For example, you may hear a knocking sound in your hot water pipes that can be loud enough to resemble water hammer. If you’re not sure about the cause of the noise, your best solution is to get in touch with a reputable plumber or plumbing company.

Melanie Asiba

Melanie is an author. She enjoys traveling, reading and trying out new things. In addition to writing for Apartment ABC. Connect with her at [email protected]

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