What is Water Hammer in Plumbing?

Water hammer, also known as hydraulic shock, is a common plumbing issue that happens when water flow suddenly stops or changes direction. This abrupt shift creates pressure waves that rattle through your pipes, often resulting in those loud, annoying banging or knocking noises.

But it’s not just about the noise; if ignored, water hammer can cause serious damage to your plumbing system. Understanding what triggers water hammer and learning how to prevent it can save you from costly repairs and keep your home’s plumbing running smoothly.

Causes of Water Hammer

Water hammer is typically caused by the abrupt stopping or changing of water flow in a plumbing system.

Here are the primary factors that contribute to this issue:

1. Quick Valve Closures

The most common cause of water hammer is the rapid closing of valves, such as those in taps, washing machines, or dishwashers. When the flow of water is suddenly stopped, the momentum of the moving water creates pressure waves that travel through the pipes, causing the characteristic banging noise. This can be particularly pronounced in high-pressure systems where water moves rapidly.

2. High Water Velocity

Water travelling at high speeds can exacerbate the effects of water hammer. In plumbing systems with large or oversized pipes, water can flow too quickly, increasing the momentum and the impact when the flow is abruptly stopped. This high velocity can make the shockwaves stronger and more disruptive.

3. Long Pipe Lengths

Longer pipes provide more space for pressure fluctuations to develop, which can intensify the water hammer effect. As the pressure waves travel further down long pipes, the noise and potential for damage can increase, especially in multi-storey buildings where water needs to travel vertically over long distances.

4. Loose or Unsupported Pipes

Pipes that are not securely fastened can move and vibrate when pressure changes occur, amplifying the noise associated with water hammer. If the pipes are loose, the vibrations can cause the pipes to bang against walls or other structures, making the noise even louder and potentially causing physical damage over time.

5. Worn Valves

Valves that are old, worn, or damaged may not close properly, leading to increased pressure surges and water hammer. These valves may allow water to flow erratically, causing sudden changes in pressure that contribute to the hydraulic shock.

Effects of Water Hammer

While the noise caused by water hammer is the most noticeable effect, the issue can have several other, more serious consequences if not addressed:

1. Noise Pollution

The most immediate effect of water hammer is the loud banging or knocking sounds that can occur when you turn off a tap or an appliance shuts off. This noise can be annoying and disruptive, particularly in a quiet home environment.

2. Pipe Damage

Over time, the repeated stress from water hammer can weaken pipes and joints, leading to leaks, cracks, or even burst pipes. This can result in costly repairs and potential water damage to your home. In severe cases, the repeated impact of the water hammer can cause pipes to become dislodged or even break, leading to significant plumbing issues.

3. Appliance Wear and Tear

Appliances such as washing machines and dishwashers may experience accelerated wear and tear due to the shock waves caused by water hammer. This can shorten the lifespan of the appliances and lead to more frequent breakdowns, requiring costly repairs or replacements.

How to Prevent Water Hammer

Preventing water hammer is essential to maintain the longevity of your plumbing system and avoid the disruptive noise it causes. Here are some effective solutions to prevent water hammer in your home:

1. Install Water Hammer Arrestors

Water hammer arrestors are devices designed to absorb the shockwaves caused by water hammer and prevent them from travelling through the pipes. These arrestors are typically installed at specific points in the plumbing system, such as near washing machines, dishwashers, or taps that are prone to causing water hammer. By absorbing the shock, these devices help to silence the banging noise and protect the plumbing system from damage.

2. Adjust Water Pressure

High water pressure can contribute to water hammer. Installing a pressure-reducing valve can help regulate the water pressure in your plumbing system, reducing the risk of water hammer. Lowering the water pressure can also help prevent leaks and reduce wear on your plumbing fixtures and appliances.

3. Secure Loose Pipes

Inspecting and securing any loose pipes can help minimise movement and vibrations that contribute to water hammer. Use pipe supports or clips to secure pipes more firmly to the walls or other structures. Ensuring that your pipes are properly anchored can prevent them from banging against surfaces when pressure changes occur.

4. Install Air Chambers

Air chambers are vertical sections of pipe that contain air, acting as a cushion to absorb shockwaves. These chambers are installed near taps or appliances that are prone to causing water hammer. However, it’s important to note that air chambers can become waterlogged over time and may require regular maintenance to remain effective. If your home has air chambers, they should be checked periodically to ensure they are functioning correctly.

5. Gradual Valve Closure

Whenever possible, avoid abruptly shutting off water valves. Gradually closing valves can reduce the momentum of the water flow and minimise pressure fluctuations, thereby reducing the likelihood of water hammer. This is a simple yet effective way to prevent the issue, especially in older plumbing systems that may be more susceptible to hydraulic shock.

Fixing Water Hammer in Your Plumbing System

If water hammer is already causing noise or issues in your plumbing system, there are practical steps you can take to address it. Here’s how to fix water hammer and protect your pipes:

Check and Secure Loose Pipes

Inspect your plumbing for loose or unsupported pipes. Use pipe straps or clips to secure them firmly to walls or other surfaces. Tightening the pipes can prevent them from vibrating and reduce the banging sounds caused by water hammer.

Install Water Hammer Arrestors

A water hammer arrestor absorbs the shockwaves caused by sudden changes in water flow. These devices are easy to install and work effectively to silence the noise and prevent damage. They are typically placed near appliances or taps where water hammer occurs.

Reduce Water Pressure

High water pressure increases the likelihood of water hammer. Test your home’s water pressure using a gauge, and if it’s too high, install a pressure-reducing valve. Adjusting the pressure to safe levels protects your pipes and reduces stress on appliances.

Flush Your Air Chambers

If your home has air chambers, they may become waterlogged over time and stop functioning. To fix this, turn off your water supply and drain the plumbing system. This allows air to refill the chambers, restoring their ability to cushion pressure surges.

Replace Worn or Faulty Valves

Old or damaged valves may not close properly, worsening water hammer. Replacing worn valves with new ones ensures smoother water flow and reduces the risk of sudden pressure changes.

Use Slow-Closing Valves

Switching to slow-closing valves on taps or appliances prevents abrupt water stoppages, reducing the shockwaves that cause water hammer. These valves are especially useful for washing machines and dishwashers.

Consult a Plumber

If these solutions don’t resolve the issue, it’s best to consult a professional plumber. A persistent water hammer could indicate more complex problems in your plumbing system that require expert attention.

Conclusion

Water hammer is a common plumbing issue that can lead to significant problems if not addressed. The loud banging noises associated with water hammer are not just an annoyance—they can also indicate underlying issues that could damage your plumbing system over time. Understanding the causes and effects of water hammer, along with implementing preventive measures, can help maintain a quiet and efficient plumbing system in your home.

Whether it’s installing water hammer arrestors, adjusting water pressure, or securing loose pipes, taking steps to prevent water hammer will protect your plumbing system and improve your overall home comfort. If you experience persistent water hammer issues, it may be best to consult a professional plumber to assess your system and recommend the most effective solutions.

Experiencing water hammer in your home? Contact our expert plumbers today to diagnose the issue and provide effective solutions to protect your plumbing system and ensure a peaceful home environment.

Frequently Asked Questions

What causes water hammer in my plumbing system?

Water hammer is typically caused by the sudden stoppage or change in water flow, often due to quickly closing valves, high water velocity, long pipe lengths, or loose pipes. These factors create pressure fluctuations and shockwaves that result in loud banging noises.

Can water hammer damage my plumbing system?

Yes, over time, the repeated stress from water hammer can weaken pipes, leading to leaks, cracks, or even burst pipes. It can also cause increased wear and tear on appliances, potentially shortening their lifespan.

How can I prevent water hammer in my home?

Preventing water hammer can be achieved by installing water hammer arrestors, adjusting water pressure, securing loose pipes, installing air chambers, and avoiding abrupt valve closures. Regular maintenance and inspections can also help identify and address potential issues before they become severe.