Overview of the Problem – Banging Pipes When Taps Turn Off
At a property on Broadway in Bonbeach VIC 3196, our team at Your Choice Plumbers was called out after the owners noticed banging pipes when taps turned off following a bathroom renovation in their older unit.
The owners explained that the problem only started after the renovation was completed. The new bathroom had been fitted with modern mixer taps to the basin, shower and bath, and since then the pipe noise had become very noticeable. The loudest banging was happening at the basin mixer, especially when the client demonstrated shutting the tap off quickly and, more specifically, when the hot side of the mixer was turned off.
This is exactly the kind of issue where homeowners start asking, “why do my pipes bang when I turn the tap off?” or “why did my new mixer taps suddenly make the pipes noisy?” As an experienced plumber Bonbeach, we often find that older plumbing systems can tolerate slow-closing taps for years, but once modern mixer taps are installed, the fast shut-off action can expose underlying pressure and valve issues very quickly.
Why the Noise Started After the Bathroom Renovation
As part of the investigation, we looked at the rest of the unit plumbing and compared the renovated bathroom fixtures with the older original taps still in the kitchen and laundry.
In the older parts of the unit, the fixtures were still fitted with traditional wall taps using separate hot and cold handles with jumper valves and washers. These taps are closed gradually by turning the spindle, which slows the water movement more gently.
By contrast, the new bathroom mixer taps shut off almost instantly.
That difference was a major clue.
The old plumbing had effectively been operating for years with slower-closing fixtures, but once the new mixer taps were installed, the water flow was being stopped much more suddenly. That sudden shut-off created the classic water hammer effect, which explained why the banging noise only began after the renovation.
Checking the Real Cause of the Water Hammer
We explained to the client that pipe banging is usually not caused by the tap itself alone — it is usually the tap revealing an underlying system problem.
To diagnose the real cause properly, we checked:
- the mains water pressure to the unit
- the hot water system setup
- the existing hot water isolation/control valve arrangement
The mains water pressure was recorded at 580 kPa, which is above the recommended 500 kPa limit under AS/NZS 3500.
This was a major finding because excessive water pressure makes water hammer much worse, especially when mixer taps or other fast-closing valves are introduced into an older plumbing system.
Why the Hot Side Was Banging More Loudly
We then inspected the hot water system, which was a Vulcan 135L outdoor mains pressure gas hot water system, around 10 years old.
On the supply line to the hot water system, the unit still had an older-style 15mm duo valve. From experience, these older valves are known to contribute to banging and shock noise on hot water pipework as they wear over time.
That explained another important symptom the client had demonstrated:
- the noise was especially loud when shutting off the hot side of the basin mixer
So in this case, the problem was not just high pressure in general. The system also had an aging hot-side control valve contributing to the shock effect in the hot water pipework.
Repair and Water Hammer Solution
We explained our findings clearly to the client and recommended a two-part solution to properly reduce the pipe noise and protect the system.
We supplied and installed:
- 20mm in-line Zurn pressure regulating valve
- 15mm Tomson Lead Free Non Return Isolation Valve C&C
Both components were sourced from Reece Plumbing Seaford.
The pressure regulating valve was installed to reduce the incoming mains pressure to a safer operating level, while the new hot water isolation / non-return valve replaced the aging duo valve on the hot water supply.
Final Testing and Result
Once the new components were installed, we tested the system again.
The result was immediate:
- the banging pipes when taps turned off disappeared
- the bathroom mixer taps operated normally
- the hot-side shut-off noise was resolved
This confirmed that the water hammer had been caused by a combination of:
- excessive mains pressure
- sudden shut-off from new mixer taps
- a worn hot-side control valve on the older plumbing system
Long-Term Benefits of the Repair
We also explained to the client that this repair was not only about stopping the noise.
By installing the pressure regulating valve and new hot water isolation valve, the older plumbing system was now also better protected against:
- high pressure surges
- increased night-time pressure when water demand drops
- premature tap cartridge wear
- shorter hot water system life
- increased risk of burst water pipes
That meant the repair improved not only comfort, but also the long-term protection of the property’s plumbing system.
Outcome and Client Result
- water hammer accurately diagnosed
- mains pressure confirmed above compliant limit
- aging hot-side duo valve identified as contributing factor
- PRV installed to reduce pressure
- new hot water isolation / non-return valve installed
- banging pipes eliminated
The owners were extremely pleased that the problem was solved properly and that the new bathroom could now be used without the loud pipe noise.
Compliance & Prevention Insight
This case highlights why banging pipes when taps turn off often becomes more obvious after a bathroom renovation.
New mixer taps do not usually “cause” the plumbing problem — they simply expose issues that were already sitting in the system, especially:
- high water pressure
- older worn valves
- older plumbing layouts not designed for sudden shut-off fixtures
It also reinforces why pressure control is one of the most important upgrades in older homes and units. Without it, water hammer can continue damaging pipework, valves, tap cartridges and hot water systems over time.
Compliance with Australian Standards
All work carried out by Your Choice Plumbers is completed in accordance with the relevant plumbing standards, including the pressure requirements referenced under AS/NZS 3500.
In simple terms, this means your plumbing pressure is checked and controlled properly to help reduce noise, protect fixtures, and reduce the risk of long-term plumbing damage.
Our Home Plumbing Experts Approach
As part of our Home Plumbing Experts approach, we focus on both repair and prevention.
We offer a Complimentary Property Protection Audit as part of our service, assessing key areas like water pressure, hot water temperature, and flexible hoses — helping homeowners stay ahead of potential plumbing failures and avoid unexpected water damage.
Find out more about our water hammer noisy pipes Melbourne services.