Stop Banging, Knocking & Shaking Water Pipes
Loud banging or knocking from your plumbing when a tap, washing machine, dishwasher or other fixture shuts off can be caused by water hammer.
JR Gas & Water can supply and install water hammer arrestors throughout Greater Brisbane and the Gold Coast to help absorb sudden pressure changes and reduce shock through the water pipework.
Water hammer arrestors can be installed on suitable existing plumbing or replaced where an existing arrestor is no longer performing correctly.
What Is Water Hammer?
Water hammer occurs when moving water is suddenly stopped or changes direction.
Quick-closing valves can cause a rapid pressure change through the pipework, producing symptoms such as:
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Banging pipes
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Knocking inside walls
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Pipes shaking when a fixture shuts off
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Vibration from water lines
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Sudden thumping noises
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Noise when a washing machine valve closes
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Noise when a dishwasher shuts off
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Noise when mixer taps are turned off quickly
The cause should be assessed before assuming an arrestor alone will solve the problem.
How Does a Water Hammer Arrestor Work?
A water hammer arrestor provides a small pressure-absorbing chamber within the plumbing system.
When water flow stops suddenly, the arrestor helps absorb the pressure surge rather than allowing the shock to travel through the pipework.
Correct positioning is important.
An arrestor generally provides the greatest benefit when installed close to the fixture or valve creating the pressure surge.
What's Included?
Standard water hammer arrestor installation includes:
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Supply of a suitable water hammer arrestor
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Installation onto accessible suitable existing pipework
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Required standard connection fittings
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Isolation of the water supply
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Reconnection of disturbed plumbing
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Pressure testing
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Leak testing
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Operational testing
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Basic assessment of the water hammer symptoms
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Basic clean-up of the immediate work area
Where the existing plumbing needs alteration beyond the standard connection, additional work may be required.
New Water Hammer Arrestor Installation
Choose a new installation where there is currently no arrestor fitted.
Common applications include:
The best location depends on which fixture is causing the water hammer and how the existing plumbing is configured.
Water Hammer Arrestor Replacement
Existing arrestors can deteriorate or stop effectively absorbing pressure changes over time.
We can remove and replace an existing accessible arrestor where the surrounding plumbing remains suitable.
Replacement may be appropriate where:
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Water hammer has returned
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An existing arrestor is leaking
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The arrestor is corroded
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The fitting has been damaged
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The plumbing is being upgraded
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An older arrestor is no longer effective
Washing Machine Water Hammer
Washing machines are a common source of water hammer because their internal solenoid valves can shut the water supply very quickly.
If banging occurs when the washing machine:
a water hammer arrestor installed near the washing machine connection may help.
Both hot and cold supplies may need to be considered depending on the appliance and installation.
Dishwasher Water Hammer
Dishwashers also use fast-acting water valves.
If the pipework bangs when the dishwasher fills or stops filling, we can assess whether installation of a water hammer arrestor near the appliance supply is appropriate.
Water Hammer From Taps & Mixers
Water hammer can also occur when taps or mixers are shut quickly.
This is particularly noticeable with:
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Lever mixers
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Quarter-turn taps
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High-flow fixtures
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High water pressure
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Long pipe runs
Installation of an arrestor may help, but excessive pressure or poorly secured pipework can also contribute to the problem.
Water Pressure Matters
Water hammer can be made worse by excessive water pressure.
Where appropriate, JR Gas & Water may check the property's water pressure as part of assessing the issue.
If pressure is too high, installing a suitable pressure limiting valve may be more appropriate or may be required in addition to a water hammer arrestor.
Loose Pipework Can Also Cause Banging
Not every banging pipe is caused solely by hydraulic shock.
Noise can also occur where pipework:
A water hammer arrestor cannot physically secure loose pipework.
Where the cause appears to be structural pipe movement rather than pressure shock, additional investigation or access may be required.
Where Can an Arrestor Be Installed?
Depending on the plumbing layout, arrestors can be installed:
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At washing machine connections
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Near dishwasher connections
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Under sinks
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In laundries
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Near quick-closing fixtures
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On accessible branch pipework
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At other suitable points close to the source of the water hammer
Access and connection type determine whether the installation falls within the standard scope.
What's Not Included?
Standard installation does not include:
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Opening walls or ceilings
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Significant pipework alterations
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Long pipe runs
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Re-piping of the property
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Repair of loose concealed pipework
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Pressure limiting valve installation
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Replacement of unrelated taps or appliances
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Cabinet modifications
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Wall repairs
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Painting
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Rectification of unrelated plumbing defects
Additional work can be assessed where required.
Water Hammer Arrestor vs Pressure Limiting Valve
These perform different functions.
Water Hammer Arrestor
Designed to help absorb sudden pressure shock caused by rapid changes in water flow.
Pressure Limiting Valve
Designed to control the ongoing water pressure supplied to the property or part of the plumbing system.
Some properties may benefit from one or both depending on the cause of the problem.
Frequently Asked Questions
Can you install a water hammer arrestor?
Yes. JR Gas & Water can install new arrestors or replace existing ones on suitable accessible plumbing.
Will a water hammer arrestor stop banging pipes?
It can significantly reduce water hammer where sudden valve closure is the cause.
It will not necessarily solve noise caused by loose pipework, excessive pressure or other plumbing problems.
Can you install one for a washing machine?
Yes. Washing machines are one of the most common applications for water hammer arrestors.
Can you install one for a dishwasher?
Yes, provided there is a suitable accessible connection point.
Do I need one on both hot and cold pipes?
It depends on which water supplies and fixtures are creating the pressure shock.
Can high water pressure cause water hammer?
High pressure can contribute to water hammer and increase the severity of the pressure surge.
Can you replace an existing water hammer arrestor?
Yes. Existing arrestors can be replaced where accessible and the surrounding plumbing is suitable.
What if the noise is inside the wall?
The first step is determining whether the noise is hydraulic water hammer or physical movement of the pipework.
If concealed pipework is loose, access may be required to secure it.
