Wood Fireplace Installation in Mulgrave: Flue Through Existing Chimney
Wood fireplace installation Mulgrave case study — new wood heater into existing chimney, flue liner, hearth pad, compliance. Prime Plumbing…
How to Fix Water Hammer: A Plumber's Guide for Melbourne Homes
How to Fix Water Hammer: A Plumber's Guide for Melbourne Homes, a Prime Plumbing & Gasfitting plain-English guide to how to fix water hammer for Melbourne homeowners. Below we cover what works, what doesn't, and when to call a licensed plumber.
Quick answer: Water hammer fixes range from a $30 tap-washer replacement up to a couple of hundred for a pressure-limiting valve install. The right fix depends on what's causing the hammer. The four most common fixes are: (1) replace worn tap washers, (2) fit a water hammer arrestor at the offending fixture, (3) install a pressure-limiting valve at the meter, and (4) secure loose pipework against framing. A plumber can identify which one applies in a single visit.
If you've already read what causes water hammer, you'll know the bang isn't a single problem, it's a symptom of one of four underlying causes. The right fix depends on which cause applies to your home. Here's how each fix works, what's in DIY territory, and when you need a licensed plumber.
The four fixes that actually work
1. Replace worn tap washers (DIY-friendly)
If your hammer is rapid "machine-gun" drumming that only happens at one tap and only when the tap is almost closed, it's almost certainly a worn washer. The flat rubber washer (or the jumper valve assembly in a brass screw-down tap) has degraded and is fluttering against the seat instead of sealing cleanly.
The fix:
- Turn off water at the meter
- Remove the tap handle and bonnet
- Lift out the spindle and inspect the washer at the bottom
- Replace washer (or the whole jumper valve if the brass is worn)
- Reassemble and turn the water back on
If the hammer continues, the seat itself may be damaged, that needs a tap reseating tool or a plumber.
Cost guide: Washers cost a couple of dollars each from any hardware store. The DIY version takes about 20 minutes per tap. A plumber's call-out for the same job typically includes diagnosis and re-seating if the brass needs it.
2. Fit a water hammer arrestor (plumber's job)
If a single specific appliance (washing machine, dishwasher, toilet fill valve) makes the bang, the cleanest fix is a water hammer arrestor: a small device with an internal sealed air or piston chamber that compresses to absorb the shockwave when the appliance valve closes.
You fit an arrestor between the existing isolation tap and the appliance hose. They're rated by AS/NZS 1182 in Australia and come in a few common sizes. The right one for your home depends on flow rate at the appliance.
Arrestors are technically a screw-on plumbing fitting, but anything connected to the mains supply line should be fitted by a licensed plumber under Victorian regulations. If it leaks, your insurance will ask whether the work was done by a BPC-licensed plumber: and an unlicensed install is grounds to deny a water-damage claim.
Real example: On a recent Camberwell callout, the homeowner had bought an arrestor from Bunnings and fitted it themselves to the dishwasher. It actually worked, the hammer stopped, but when an unrelated leak developed three weeks later, their insurer checked the install and flagged it. A licensed re-fit took 15 minutes and would have cost less than the insurance claim hassle.
3. Install a pressure-limiting valve (plumber's job)
If your hammer is across the whole house: every appliance, every tap when shut quickly, your incoming mains pressure is probably too high. AS/NZS 3500.1 caps fixture-side pressure at 500 kPa for a reason: above that, valves close harder, fittings stress more, and water hammer gets louder.
A pressure-limiting valve (PLV) sits at the water meter or just inside the property and steps the pressure down to a safe limit (usually set around 350-450 kPa). Once it's in, the hammer drops dramatically across the whole house and you usually see a few side benefits:
- Tap cartridges last longer
- Mixer cartridges stop weeping
- Hot water relief valve stops dripping
- Appliances last longer
Real example: On a recent Brighton callout, mains pressure measured 720 kPa at the meter, almost 50% over the AS/NZS 3500 limit. A PLV install (about 90 minutes on-site) brought it to 400 kPa and the hammer disappeared completely.
4. Secure loose pipework (plumber's job)
If the hammer sounds different in different parts of the house, louder in some rooms than others, it's often the pipe banging against framing, not the shockwave itself making the noise. Supply pipes that aren't properly clipped to a joist or strapped against the wall move when a shockwave passes through, and the moving pipe knocks against whatever it's near.
The fix is access-dependent: visible pipework in the roof cavity or under the floor can be re-clipped in a single visit. Pipework concealed inside walls is harder, sometimes you have to settle for fitting an arrestor at the offending fixture rather than tearing open plaster.
Common access points:
- Roof cavity (especially around hot water unit connections)
- Under-floor crawlspace in older homes
- Behind kitchen cabinets where supply lines run from the meter
- Service cupboards near washing machines and dishwashers
What's NOT a real fix (despite what the internet says)
A few "fixes" you'll see online don't actually work in Australian residential plumbing:
- "Drain your whole house water system to recharge air chambers": this is American advice. Australian residential plumbing doesn't typically use field-built air chambers. Draining the system might briefly help if you have an arrestor with a damaged internal bladder, but it doesn't fix the underlying cause.
- "Wrap the pipe in foam": masks the noise but the shockwave still stresses joints and fittings.
- "Replace all the supply line": overkill 99% of the time. Sectional fixes target the actual cause.
What you'll spend
I'm not going to fabricate exact prices because every property is different. Indicative ranges:
| Fix | Typical scope |
|---|---|
| Worn tap washer | Smallest fix, single tap, single visit |
| Hammer arrestor at one appliance | 30-60 min on-site, parts under $100 |
| Pressure-limiting valve | 60-90 min on-site, parts $150-300 |
| Re-clipping unsupported pipework | Depends on access, could be 30 min in an open roof cavity, or longer if walls are involved |
| Combined diagnosis + multiple fixes | A whole-home water hammer fix on a 4-bed house typically takes a half-day visit |
We quote in writing first, after diagnosis, so you know the exact cost before any work starts.
When to call us
Book a water hammer diagnosis visit if:
- The hammer happens multiple times a day
- It started after a recent renovation or appliance install
- You can see visible pipe movement
- You've got a recent leak around a tap or under a sink
- The "machine-gun" drumming has been going on for weeks
Most water hammer fixes complete in one visit.
Service area
Prime Plumbing & Gasfitting fixes water hammer issues across Melbourne's eastern, south-eastern, inner-east and bayside suburbs. See all suburbs we service
Book a water hammer fix
Loud bangs in your pipes? Call 0475 407 670 or send your address through the contact form.
- BPC #103414: Plumbing Industry Commission licensed
- Type A Gasfitter: registered with Energy Safe Victoria
- 4.8 stars on Google
- Fixed-price written quote before any work
- Compliance Certificate issued where the work requires one
For shockwave-related leaks, see our burst pipe repair page.
About the author
Alister Williams is the founder and lead plumber of Prime Plumbing & Gasfitting. He's been licensed under BPC #103414 for over a decade, holds Type A Gasfitter endorsement with Energy Safe Victoria, and is a member of the Master Plumbers Association of Victoria.
When to Call a Licensed Plumber
Some plumbing problems are DIY-friendly; others need a licensed professional under Victorian law.
Anything involving gas, sewer drainage, hot water units, backflow prevention, or work behind tiled walls must be handled by a licensed plumber or gasfitter.
Frequently asked questions
You can technically screw one in (they're standard plumbing thread), but anything connected to the mains supply line in Victoria requires a licensed plumber. If the install leaks and damages the property, an insurance claim will be denied if the install wasn't done by a BPC-licensed plumber. The cost saving from DIY isn't worth the insurance risk.
A quality PLV typically lasts 8-12 years in Australian residential conditions before the internal seat starts wearing. The first sign it's failing is usually the hammer returning slowly over a few months. They're easy to replace once installed, no major plumbing work, the existing fittings stay in place.
Yes, indirectly. Water hammer stresses fittings, mixer cartridges and appliance solenoid valves. Properties with chronic hammer typically replace tap cartridges every 2-3 years instead of the normal 5-10. A PLV install pays for itself within a few years on tap-cartridge wear alone, plus the longer appliance life.
Plumbing warranties cover the install workmanship for normally 6-12 months. Warranty doesn't cover developing water hammer caused by changes elsewhere in your system (new appliance fitted, mains pressure changed). Appliance warranties often exclude damage caused by water hammer, your dishwasher inlet valve isn't rated for repeated shock loading, and the manufacturer knows it.
If your hammer is the rapid "machine-gun" type at one specific tap, replacing the washer is the cheapest fix, well under $50 in parts and 20 minutes of labour. If your hammer is across multiple fixtures, a pressure-limiting valve is typically the highest-impact fix per dollar.
Before You Book
A quick checklist to share with your plumber when you book:
- When did the issue start?
- Is it isolated to one fixture or multiple areas?
- Are there any visible leaks, smells or unusual sounds?
- Have you turned off the relevant isolation valve?
If you're unsure, Prime Plumbing & Gasfitting can inspect the issue and explain the options before any work starts. Call 0475 407 670 or request a quote online.
