What is Water Hammer?
Have you ever turned your taps off quickly and there’s been a loud banging in your pipes? There’s a strong chance that’s water hammer.
It’s an odd term, as most people wouldn’t associate a hammer with plumbing. But the term is a colloquial reference to hydraulic shock.
Hydraulic shock is what happens when water suddenly stops or changes direction. Essentially, it’s a momentum swing which results in a large shock wave or pressure surge within the pipes.
Water hammer doesn’t always necessarily sound the same. Sometimes it may just be one loud bang when the water flow is shut off and the pipe itself may knock against any joists, framing or the wall. Other times it may be repetitive banging or shuddering as the shock wave moves back and forth.
At home, you’re most likely to notice the signs of hydraulic shock when your toilet stops flushing or you turn off a tap, while the dishwasher and washing machine can also experience it when a valve shuts.
6 Ways to Stop Water Hammer
Adjust the Water Pressure
One reason you might experience water hammer is that the water pressure is too high. The Australian maximum water pressure for a residential home is 500kPa (kilopascals). It’s a balanced number which ensures your home has a steady flow without damaging the plumbing system.
However, it’s common for older homes to have high water pressure, and many cases have reportedly been 1000kPa or above. If the pressure is too high and taps are shut off quickly, there will be a recurring issue when the water slams against a closed valve.
Rather than put up with the noise, it’s important to contact a plumber who can provide a number of solutions to reduce high pressure to a standard range.
There will be no negative impact on the water supply or showering.
Clear Out Air Chambers
An air chamber is a part of the water supply pipe, providing an air cushion to absorb hydraulic shock. Once a water valve closes the air chamber prevents water from loudly banging against the pipes.
Air chambers are often located along pipes where the water supply regularly stops and starts, such as washing machines. But it’s handy to have multiple supply lines protected with several air chambers throughout your home’s plumbing.
In case an air chamber does become waterlogged, the cushioning will not work as properly. The first solution is to drain a plumbing system. To do this, just:
- Turn off the main water valve
- Open the highest faucet in your home
- Open the lowest faucet in the home
Water will flow out of the lower tap, while air chambers will fill with air to improve cushioning. If the problem is not solved, however, more troubleshooting may be required.
Install Water Hammer Arrestors
One of the most straightforward solutions for water hammer is installing a water hammer arrestor. Arrestors houses an air-filled cylinder which absorbs the force of the hydraulic shock when a valve shuts off.
Water hammer arrestors can be installed between water supply lines and the shut-off valve, providing an isolated solution for both the hot and cold water supply. An arrestor is a simple way to make sure your plumbing is better protected.
Reinforce Pipes and Plumbing
While your water pressure could be perfect, the issue might be with pipework itself. If any of the saddle support is loose, such as the wooden joists or pipe straps, then the pipes will bang around noisily.
To remedy this, check all pipework and support where possible. Pipe straps can often be tightened with a screwdriver, while additional straps can be installed. Some varieties are also padded for additional vibration reduction.
Insulation is also a handy way to cushion any plumbing. The main outcome is to retain heat, but the foam tubing also absorbs movement and can counteract some water hammer.
Meanwhile, not all pipework is easily accessible, and a licensed plumber is often the best choice for a full and thorough investigation.
Install a Pressure Limiting Valve
When taps are off, the pressure inside pipes builds to a static pressure of the incoming main water supply. While water pressure should have a maximum limit of 500kPa, the incoming water pressure fluctuates, and so does the pressure inside the pipework.
A pressure limiting valve can be installed at the water meter to ensure the water flowing throughout your pipes does not exceed 500kPa. If the level was to increase, both your plumbing and plumbed appliances like washing machines could be negatively impacted.
Using both a water hammer arrestor and pressure regulator provides a two-pronged approach to maintaining a steady and safe water supply throughout any plumbing system.
Inspect Your Plumbing
Take a look at your entire home’s plumbing. If the water flow appears irregular at any point, or there is a water leak, it could be an opening for a water hammer problem.
Check that there are no leaking taps, leaking toilet suites or even damaged hot water systems. If you have an electric storage hot water system on a heating tariff that heats through the night, pipework may shudder when the hot relief valve dumps water.
The issue could even be in the garden. An irrigation system is typically connected to a solenoid valve and a quick shut-off is just as susceptible to water hammer.
Alongside additional protection like a pressure regulator or air chamber, updated tapware can also help. Worn out washers and valves can prove to be a nuisance, especially in high use settings like the washing machine, dishwasher or shower.
If you need assistance with any water hammer problem that may cause additional headaches, please call Jim’s Plumbing.
Our licensed plumbers operate across Australia and are always ready to provide 24/7 service.