Table of Contents:

  1. What is water hammer
  2. What are the typical causes and what should you do about it
  3. What happens if you don’t fix the water hammer issue
  4. Conclusion
Cartoon image of a hammer coming out of the water

What is Water Hammer?

Water hammer, also referred to as “water hammering,” is a plumbing phenomenon that many homeowners and building managers might have encountered, even if they didn’t know its technical name. It’s that jarring, loud banging or thudding sound you hear in your pipes, especially after quickly shutting off a water source.


Identifying Water Hammer:

  • Sound: The most obvious sign of water hammering is the noise. It’s a sudden, loud bang that can be quite startling. It typically occurs right after a faucet is turned off or a washing machine or dishwasher stops filling.
  • Vibration: Along with the sound, you might feel a slight vibration in the wall or floor where the pipes run.
  • Recurring Issue: If it’s a one-time noise, it might not be water hammer. But if you consistently hear the sound after shutting off a water source, it’s a clear sign.


The noise and vibration are caused by a sudden stoppage of water flow, leading to a pressure surge or wave that rattles the pipes. Think of it as a mini shockwave that travels through the plumbing system. This sudden stop and the resulting wave can cause pipes to shake and bang against their surroundings, leading to the characteristic sound of water hammering.


Now that we’ve identified what water hammer is and how to recognize it, let’s delve into its causes and the necessary remedies.

What are the typical causes of water hammer and what needs to be done for each

Water hammer is not just a simple annoyance; it’s a symptom of underlying issues in your plumbing system. Understanding the root causes can help in effectively addressing and preventing the problem. Here are the typical causes of water hammer and the recommended solutions for each:

1. Quick-Closing Valves:

  • Cause: Modern fixtures like washing machines and dishwashers have quick-closing valves that can shut off water abruptly. This sudden stoppage can create a shockwave in the pipes, leading to water hammer.
  • Solution: Installing water hammer arrestors or shock absorbers can help. These devices cushion the shockwave created by the sudden stoppage of water, preventing the loud banging noise. They are typically installed close to the quick-closing valves.

2. High Water Pressure:

  • Cause: If the water pressure in your home or building is too high, it can exacerbate the effects of water hammer. The force of the water moving through the pipes can be strong enough to cause significant vibrations when stopped suddenly.
  • Solution: Check the water pressure using a pressure gauge. If it’s above the recommended range (typically between 50 and 70 psi), consider installing a pressure-reducing valve to maintain a safe and consistent water pressure level.

3. Air Chambers:

  • Cause: Air chambers are vertical pipes installed near faucets and valves to prevent water hammer. They work by providing a cushion of air. Over time, these chambers can become waterlogged, losing their effectiveness.
  • Solution: To restore air chambers, turn off the main water supply and open all faucets to drain the system. Once drained, turn the water supply back on. This process reintroduces air into the chambers.

4. Loose Pipes:

  • Cause: If pipes aren’t securely fastened, they can move and bang against surrounding materials when water flows through them, especially if there’s a sudden stoppage.
  • Solution: Inspect your plumbing system to ensure all pipes are securely fastened. If any pipes are loose, secure them with appropriate brackets or hangers.

5. Old or Worn-Out Pipes:

  • Cause: Over time, pipes can corrode, weaken, or become damaged. Older pipes might not be equipped to handle the effects of water hammer.
  • Solution: Regularly inspect your plumbing system for signs of wear and tear. If pipes are old or damaged, consider replacing them with modern pipes that are better equipped to handle water hammer effects.

Understanding the specific cause of water hammering in your system is crucial. By addressing the root cause, you can not only eliminate the annoying noise but also prevent potential damage to your plumbing system. In the next section, we’ll explore the implications of ignoring water hammer and the potential consequences.

What happens if you don’t fix the water hammer issue

Water hammer might initially seem like a minor inconvenience, a mere thudding noise in the walls. However, dismissing it as just an auditory annoyance can be a costly mistake. Letting water hammer persist without addressing its root causes can lead to several complications:


1. Pipe Damage: The repeated shockwaves from water hammer can weaken pipes over time. This constant stress can lead to small cracks, which might eventually cause leaks. In extreme cases, the force can even rupture a pipe, leading to significant water damage.

2. Joint and Fitting Strain: The connections between pipes, known as joints and fittings, are particularly vulnerable to the effects of water hammer. The shockwaves can loosen these connections, causing them to leak or, in worst-case scenarios, completely detach.

3. Damage to Appliances: Household appliances connected to the water supply, such as washing machines, dishwashers, and water heaters, can suffer from the effects of water hammer. The jolts can damage internal components, reduce the lifespan of the appliance, and void warranties.

4. Increased Water Bills: Even minor leaks resulting from water hammer can lead to a noticeable increase in water bills over time. This not only impacts your wallet but also wastes a precious resource.

5. Potential Mold Growth: Leaks caused by water hammer can create damp spots in walls, ceilings, or floors. These moist environments are prime locations for mold growth, which can pose health risks to inhabitants and require costly remediation.

6. Reduced Valve and Tap Lifespan: The components designed to control the flow of water, such as valves and taps, can wear out faster due to the repeated pressure surges from water hammer.

7. Aesthetic Damage: Persistent water hammer can cause visible damage to walls and ceilings, especially if leaks occur. This might require patching, repainting, or even more extensive repairs.


In essence, while the noise of water hammer might be the most immediate and noticeable effect, the potential damage it can cause to a plumbing system and a home’s structure is far more concerning. Addressing water hammer promptly not only ensures a quieter home but also prevents more significant, costly issues down the line. In the conclusion, we’ll summarize the importance of understanding and addressing water hammer in your plumbing system.


Water hammer, with its distinctive and often alarming sound, serves as a clear signal that all is not well within a plumbing system. While it might be tempting to dismiss it as a mere quirk or minor inconvenience, doing so can lead to more significant problems down the road. From potential damage to pipes and appliances to the increased risk of mold growth and aesthetic damage, the repercussions of ignoring water hammer are manifold and costly.


Understanding the causes of water hammer and taking proactive steps to address them is crucial for any homeowner or building manager. Regular maintenance, timely interventions, and a keen ear can go a long way in ensuring that your plumbing system remains in optimal condition. Moreover, by addressing water hammer at its onset, you not only safeguard the structural integrity of your property but also ensure a peaceful and quiet living environment.


Being proactive about plumbing issues like water hammer is not just a matter of comfort but also of practicality and financial prudence. Remember, in the realm of plumbing, as with many things in life, an ounce of prevention is worth a pound of cure.

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