Have you ever been alarmed by a sudden, resonant banging noise originating from your walls right after you flush the toilet or initiate your washing machine? Such noises, though unnerving, are indicative of a phenomenon known as the ‘water hammer’. It’s not only startling but can become a regular source of annoyance if left unaddressed. You might wonder why your plumbing is making noise. Perhaps you can relate to these scenarios:

  • A noticeable noise immediately after flushing the toilet.
  • A pronounced sound, especially when flushing the toilet located upstairs.
  • An echoing through the water pipes after flushing.
Why Is My Plumbing Making a Noise

What is the Cause of Banging Noises in Water Pipes?

A prevalent concern among homeowners revolves around the sudden, jarring banging sounds that often resonate from the plumbing system. When such noises frequently reverberate from your pipes, it’s a clear indication of underlying issues, primarily related to irregular water flow or elevated water pressure levels.

Several factors can contribute to these disruptive sounds but they are usually:

  1. Rapid Water Flow Cessation: Imagine a robust flow of water rushing through your plumbing, and then suddenly, a valve or faucet closes, causing the water to halt its momentum abruptly. This sudden stop can create a shockwave, leading to the banging sounds you hear.
  2. Elevated Water Pressure: When water pressure in the system surpasses the standard range, it can cause turbulent flows, which, in turn, lead to noisy vibrations and reverberations.

To address these concerns, you can install or adjust a device called a pressure reducer or regulator. This equipment serves to stabilise the water pressure within the plumbing system. In fact, many contemporary homes come pre-equipped with these mechanisms.

Why Are My Pipes Shaking and Rattling?

Your water pipes are shaking and rattling primarily because of loosened fasteners, causing them to move when water flows through. Additionally, temperature changes, especially in copper pipes, can lead to expansion and contraction, making them knock against house structures. To elaborate, most pipes are strategically secured behind walls, under floors, or within ceilings using specialized fasteners. Over time, these can weaken or detach, allowing pipes to sway with water movement.

Copper pipes, when transporting hot water, expand due to the heat and contract upon cooling. This size change can make them brush against joists, wall studs, or support brackets, resulting in those loud noises you’re hearing.

Why is My Plumbing Making a Humming Noise?

Your plumbing is making a humming noise due to excessive water pressure exceeding the system’s capacity, leading your pipes to vibrate. When water runs through these vibrating pipes, it produces a humming sound. Homes drawing from well water are especially susceptible to this issue. If you notice such a sound, it’s advisable to inspect your water tank.

When you check the tank, you’re primarily looking for:

  1. Water Pressure: Ensure that the water pressure is within the recommended range for your household. You can use a pressure gauge to measure this. Typically, residential water pressure should be between 40 to 60 psi (pounds per square inch).
  2. Pressure Relief Valve: Examine the pressure relief valve. If it’s leaking or appears faulty, it might not be releasing excess pressure properly.
  3. Air Chamber or Water Hammer Arrestor: These are designed to prevent water hammer noises and vibrations. Ensure they’re functioning correctly and not waterlogged.
  4. Expansion Tank: If you have a closed plumbing system, you should have an expansion tank installed. This tank absorbs excess pressure from heated water. Ensure it’s not waterlogged and is functioning correctly.
  5. Damaged or Malfunctioning Parts: Look for any visibly damaged or corroded parts, especially in the pressure regulating valve, which might be causing excessive pressure.
  6. Signs of Leaks: Wet spots, rust, or corrosion can indicate leaks that might be affecting the system’s pressure.
  7. Water Level: If you’re using a well, ensure that the water level is adequate and the pump is working efficiently.

What is Water Hammer?

Water hammer, often described as a loud, banging noise in plumbing systems, is comparable to a high-speed train encountering an abrupt obstacle on its track.

Much like how the train’s carriages would crash into each other upon a sudden stop, water in your pipes reacts in a similar manner, albeit on a much smaller scale.

What Causes the Water Hammer Effect?

Imagine this: when you flush your toilet, water swiftly travels through the pipes. However, the moment the toilet tank refills, a valve shuts, causing the water in motion to slam against this valve. This sudden halt generates a reverberating noise and vibration — the same as when you start a washing machine or close a tap abruptly.

Physical impact within the pipes can cause them to jolt or bang against walls or other fixtures, which likely gave rise to the term “water hammer.”

Identifying Water Hammer Sounds

The characteristic sound of a water hammer is a pounding or banging noise that emanates from your plumbing when taps are turned off or if there’s a sudden stop in water flow. These sounds arise from the rapid change in water pressure and the resulting vibrations within the pipes. At times, the swift water movement can even create a vacuum, amplifying the intensity of the hydraulic shock.

New Clips to Stop Water Hammer Vibrations
New Clips to Stop Water Hammer Vibrations

How to Address Water Hammer Issues?

The remedy for water hammer largely hinges on when your residence was constructed:

Homes Built Up To the 1960s

  • Switch off your home’s main water supply.
  • Drain all water from the plumbing system.
  • Open all taps, flush toilets, and run appliances like washing machines or dishwashers to ensure complete drainage.
  • Restore the water supply.
  • Check for any residual noises – ideally, they should have been eliminated.

Homes From the 1970s to 1990s

Houses from this era typically lack adequate water hammer safeguards. The most effective solution for these homes is the installation of a water hammer arrestor, a device that absorbs the shock and minimises the resultant noise.

Homes Constructed Post-1990

Modern homes are usually equipped with water hammer arrestors as a standard feature. If you’re still experiencing water hammer, it’s possible you might have a malfunctioning arrestor, though this is quite uncommon.

What is a Water Hammer Arrestor?

Water hammer arrestors play a crucial role in managing and mitigating the shock created when water flow is abruptly halted in a plumbing system, especially during the rapid shutting of valves.

By cushioning this shock, the arrestor helps prevent potential damage. For optimal functionality, it’s essential to select the right-sized water hammer arrestor and position it near the water supply to absorb the shock promptly.

Water Hammer and Washing Machines

Introducing a new appliance, like a washing machine, can sometimes lead to water hammer issues. This is primarily due to the appliance’s solenoid valves. These electrically operated valves regulate the water supply to the washing machine and can stop the water flow instantaneously.

Such a sudden stoppage can cause water to surge backwards, creating shockwaves that manifest as the familiar banging noise.

Do I Need to Fix Noisy Pipes?

Certainly. Noisy pipes, especially those producing sounds akin to hydraulic shocks, should not be ignored. The sound is often more noticeable in metal pipes, given metal’s superior ability to transmit sound compared to plastic. If you suspect you’re dealing with a hydraulic shock, it’s advisable to consult a professional plumber or heating engineer promptly. Overlooking this issue can lead to increased water pressure, causing vibrations and strain on your pipework, joints, and fixtures.

In extreme scenarios, these shocks can result in pipe bursts, leading to potential water damage or flooding in your home. A progressively louder banging noise is a sign of deteriorating conditions that demand immediate attention.


Water hammer and noisy pipes are more than mere household nuisances; they signify underlying issues in your plumbing system. Manifested as sudden banging or persistent humming sounds, these disturbances result from rapid pressure changes or valve closures. Ignoring them can lead to escalating problems, from the strain on pipe joints to potential flooding. Therefore, it’s imperative to understand their causes and seek timely solutions, ensuring both the longevity of your plumbing system and the tranquillity of your living environment.

Why Are My Pipes Banging Infographic

Plumbing Wizard Tips

“Inspect your home regularly for any loose pipe fastenings to avoid unnecessary noise!”

“Consider the installation of water hammer arrestors for better shock absorption!”

“Discuss with professional plumbers about the benefits of slow-closing valves for your system!”

“Proper insulation around your pipes can drastically reduce sound and prevent rattling!”

“Every now and then, drain your system to alleviate any trapped air or pressure buildup!”

Frequently Asked Questions

Why Do Pipes Bang When Flushing the Toilet?

A loud bang echoing from your pipes post-flushing is a telltale sign of a water hammer. This noise is produced by a shockwave stemming from a sudden change in water pressure. When pressurized water collides against a valve opening, it creates this loud noise. Left unaddressed, water hammer issues can escalate into more significant plumbing problems over time.

Can water hammer damage my plumbing?

Over time, the repeated shockwaves can weaken joints, damage valves, or even rupture pipes, leading to leaks and potentially costly repairs.

How can I prevent water hammer in my home?

Installing water hammer arrestors, using slow-closing valves, and adjusting high water pressure are effective preventive measures.

How does a water hammer arrestor work?

A water hammer arrestor absorbs the shock of halted water flow, reducing the impact of the water hammer and preventing damage to the plumbing system.

Are there DIY solutions for water hammer?

While professional intervention is often recommended, homeowners can try draining their system or adjusting the water pressure as a temporary solution.

What kind of professional should I consult about water hammer?

You should contact a licensed plumber or heating engineer, as they can accurately diagnose and remedy water hammer issues.

Are plastic pipes less susceptible to water hammer than metal pipes?

While plastic pipes might not transmit the noise as effectively as metal, they can still be affected by the pressure changes that cause water hammer. Both types require preventive measures and maintenance.


Lee Pearce is not just a master plumber; he’s a veritable Plumbing Wizard. With over 30 years of experience in the trenches of pipes and drains, Lee has become the go-to sage for DIY plumbing, saving homeowners thousands in potential call-out charges. As the founder of Plumbing Wizard, he’s dedicated to demystifying the complexities of home plumbing, offering easy-to-follow advice that stands the test of time and pressure. His online blog is a treasure trove of tips, tricks, and tutorials that empower everyday individuals to take charge of their home’s plumbing health. Lee’s practical wisdom is not just about fixing leaks; it’s about imparting confidence and self-reliance. When he’s not writing or elbow-deep in a plumbing project, Lee is passionate about educating the next generation of DIYers, ensuring that practical skills are passed down and preserved.

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