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How to Get Rid of Water Hammer?

Do you have a tap at home that produces a banging sound when opened? Does it shudder, vibrate or bang repetitively? All these could be signs of hydraulic shock which is also referred to as ‘water hammer’.

While some instances are not dangerous and might cause no other trouble than the annoying sound, in certain cases it can lead to burst pipes – especially at joints or corroded areas. It could also cause your pipes to shift, causing cracks or holes.

If it is a one-off occurrence, you can probably ignore the problem. However, if it persists, calling in licensed plumbers like our team at JEDI Plumbing Services is the thing to do.

What is hydraulic shock?

When flowing water is suddenly forced to stop or even change direction, due to the momentum change, pressure is generated. The pressure wave propagates back and forth through the pipe until all its energy is dissipated wherever weaknesses are found. This can include loose or corroded pipework and also washers left in the open position.

It is important to understand that sometimes the pressure wave does not produce a sound, which means that the problem is left undiscovered until serious damage occurs.

Running Tap

What causes water pipes to hammer?

Water hammer in homes can occur due to several reasons:

 Solenoid valves, like the ones used in washing machines and dishwashers, and the automatic valves used for lawn sprinklers, shut off the water supply very quickly.
 Quick closing or ‘flick type’ taps can also shut off water supply fast producing shock waves up to 3000KPa.
 Your water supply mains enter your property at a very high pressure.
 The wrong size or type of tap or pipe is used.
There is a restriction in water flow due to corrosion or any kinks in the pipes.
 There are faults in your plumbing design.
 The float control of your toilet tank is not working properly or you have pumps which start and stop often.
 For gravity hot water systems, the pressure of your supply mains can cause shock waves.

How do you fix it?

The main difficulty in fixing hydraulic shock arises from the fact that the noise location is often not the source of the problem. It takes experienced plumbers to detect and rectify the issue.

If you suspect a water hammer somewhere in your house, the first step is to run the highest tap in the house to try and remove all the air from the pipes. If the noise persists, you’ll need to call in a licensed plumber, and if you are in Sydney’s north, then our JEDI Plumbing team is on hand to assist.

  • If the shock waves are due to excess water pressure, a 500KPa pressure limiting valve can be installed at your water meter. Be careful with this though, as it can result in low pressure for taps in the upper floor bathrooms.
  • Anti-hammer valves can be installed on the washing machine and dishwasher taps which prevent rise of pressure above a predetermined level. This is achieved by discharging water directly outside.
  • Replacing flick-type mixer taps which close very quickly with soft close mixer taps with shock absorbers can help prevent hydraulic shock.
  • Hammer suppression devices may be installed on both the hot and cold water supply pipes.
  • Switch to ball valves instead of jumper valves wherever possible. For loose jumper valves which cannot be replaced, use spring load washers for pressure absorption.
  • Ensure that the silicone is distributed evenly around the pipe when a wall stud is penetrated.
  • Adhere to AS/NZS 3500 standards and clip all pipes, using stand-off clips if feasible.
  • If you have a tap that is prone to noises and vibration, consider replacing any plastic or ceramic washers with brass washers which will not break due to the vibration.

How to prevent water hammer in pipes?

As with anything else, preventing the occurrence of water hammer in your taps is always better than trying to fix them. In many cases, shoddy plumbing work is the primary reason for hydraulic shock. Choosing a good plumber who uses proper installation techniques is the only way of ensuring that this does not happen. Ensuring solid fastening during all work can help eliminate weaknesses in your plumbing system.

While water hammer arrestors work well, a good hammer arrestor costs around $50 and installing these devices on all solenoid type valves and mixer taps can become very costly. A cheaper alternative could be adding air chambers to your plumbing system. Air chambers help to reduce the impact of the shock waves and also help to eliminate the noise. These air chambers must be drained and cleaned regularly to ensure correct functioning.

If left untreated, the shock waves impose stress on your pipes causing weaknesses in your taps plumbing. This can also affect the proper working of your appliances in the long run. Neglecting hydraulic shock can even result in a call to the emergency plumber.

Our team at JEDI Plumbing, with over 15 years’ experience in domestic plumbing, uses sound practices and quality workmanship to ensure the best possible results for our clients on Sydney’s North Shore and Northern Beaches.

If you are in these areas, and are experiencing noisy, shuddering plumbing, we welcome your call on 0411 774 381.


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