The Science Behind Water Hammer and Its Effects on Plumbing

The Science Behind Water Hammer: How it Affects Your Plumbing System

Do Your Pipes or Taps Make Knocking Noises?

Knocking, thumping, banging, or rattling noises affecting water pipes, taps, and plumbing appliances is a phenomenon known as “water hammer”. Household plumbing systems subject to water hammer may experience a great deal of resultant damage, not only to the pipes themselves, but also to the expensive tapware, plumbing appliances, and solenoid valves.

What is Water Hammer and What Causes It?

Water hammer is the effect of water coming to a sudden stop. This creates a shockwave that travels through the plumbing system, and it’s this shockwave that makes the noise. Shockwaves can be caused by a tap being quickly switched off, or a quick closing valve. Water hammer is also a pretty sure sign you have high water pressure, and it’s wise to get it addressed!

Notwithstanding, several other factors may also contribute to water hammer, including (but not limited to) the likes of:

  • First and foremost, high water pressure intensifies the problem (mains-water pressure that is more than 500 kPa)
  • Quick-closing solenoid valves that are used in automatic watering systems (reticulation), as well as in household appliances such as dishwashers and washing machines Lever action “flick-mixer” taps, half -urn quick-closing ceramic disc taps, and ball valves.
  • Some versions of hot water systems, such as instantaneous gas and electric water heaters as well as HWS pressure relief valves
  • Inferior plastic tap washers that cause an annoying “rattling” or “vibrating” type of noise
  • Loose or incorrectly clipped water pipes, including pipes secured with light-weight saddle clips
  • Long lengths of copper pipes installed in ceiling spaces that have been clipped in a straight line.

How to Fix Water Hammer

As you can see, there are numerous causes of water hammer and no single solution, as there is frequently a complex array of procedures and techniques used in the analysis and correction of water hammer. However, when attempting to control water hammer, the first priority should always be to ensure that the mains water pressure is within an acceptable and workable set of parameters.

High water pressure can be the single biggest contributor to water hammer, especially throughout Perth’s Hills and Foothills, where mains water pressure is regularly delivered to households at 700 to 800 kPa and can even be as high as 1500 kPa and above, especially during night times. It is also one of the biggest contributors to burst water pipes and connectors.

To avoid damage to water pipes, tapware, pressure valves, and plumbing appliances, the mains water pressure should be restricted to a maximum of 500 kPa, as suggested by manufacturers and Australian Plumbing Standards (AS 3500.1 clause 3.3.4, – maximum water pressure 500 kPa).

Also, and contrary to popular belief, reticulation will work better if water pressure is not too high or excessive (should be no more than 500 kPa), as excessively high mains water pressure creates “water vapour” that will disperse in the lightest of breezes.

Your Local Water Hammer Plumber in Perth Hills

The best course of action in bringing water hammer under control is to engage a reputable Master Plumber that has experience and success in solving water hammer issues, such as KALAMUNDA PLUMBING PLUS, which has a long and proud history of providing Service Excellence throughout Perth’s Hills and Eastern Suburbs.

Call us now at (08) 9291 6000.


How can I tell if I have water hammer in my pipes?

You may be experiencing water hammer if you hear a loud banging noise coming from your pipes, especially after turning off a tap or valve. You may also notice pipes vibrating or rattling.

How long does it take to fix water hammer?

The amount of time it takes to fix water hammer depends on the cause and severity of the problem. In some cases, it may be a quick fix, such as installing an air chamber. In other cases, it may require more extensive repairs or replacement of parts of the plumbing system. A qualified plumber will be able to give you a better idea of the time frame for the specific issue you are facing.

Are there any warning signs that I should be aware of before water hammer occurs?

Some warning signs to be aware of include a change in water pressure, leakage or drips in pipes or valves, or strange noises coming from the pipes. It’s also a good idea to have your plumbing system inspected by a professional plumber on a regular basis, to catch any potential issues before they become bigger problems.


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