Water Hammer Wellington

Water hammer is the bang, knock or shudder that follows when moving water is stopped suddenly. Water is heavy and does not squash, so when a valve snaps shut the column of water inside the pipe has nowhere to go. The shock wave runs back along the line, and if the pipe is loose it hits a joist, a stud or another pipe on the way.

It is easy to treat as just a noise, but every bang strains joints, appliance valves and flexible hoses. Over months that can open up a slow leak somewhere you will not see it, which in most of Wellington means it will not show up on a water bill either. The good news is that the cause is usually clear once someone listens properly, and the fix is often small.

Pricing: quotes are free, and every job gets a fixed price before we start, so there are no surprises on the invoice.

Water Hammer Jobs We Handle Across Wellington

• Water hammer
• Banging pipes when tap turned off
• Noisy water pipes
• Washing machine water hammer
• Water hammer arrestor installation
• Knocking pipes under house

What the noise is telling you

The type of sound and when it happens point to the cause, so it helps to notice:

• One loud bang when the washing machine or dishwasher finishes filling
• A knock when someone flicks a lever mixer off quickly
• A rapid rattle from a toilet cistern as it finishes refilling
• Banging that seems to travel under the whole floor
• A hum or groan while a tap is running, rather than when it stops
• Noise that is louder late at night than during the day

Why Wellington homes bang

Fast-closing valves are the usual trigger. Level, the BRANZ sustainable building site, lists lever taps with ceramic disc cartridges, washing machine solenoid valves, spring-closing valves and pumps as common sources. A new dishwasher can make an old house start banging the day it goes in, because its inlet valve shuts far faster than the old one did.

How the pipe is held matters just as much. Many older Wellington houses sit on timber piles with pipe running through the subfloor, held by a handful of clips that have rusted, loosened or dropped off over the years. In villas in Newtown and Mt Victoria, and in the state houses of Miramar, Naenae and Tawa, it is common to find copper or galvanised pipe hanging free between joists. A shock that would be silent in a well-supported pipe turns into a bang when the pipe can swing. Level notes water hammer mostly occurs in metal pipe, though plastic can also be affected.

How It Works

Pressure on a hilly network

The faster water is moving, the harder it hits when it stops, so high pressure makes water hammer worse. In a city built on hills, the pressure at your tap depends a lot on how far your house sits below the reservoir that feeds it, so two homes a few streets apart can see very different readings. Level notes that pressure can reach 900 kPa or more in some places, and suggests a licensed plumber can fit a pressure limiting valve where high pressure is the problem, after checking it suits your fittings.

We measure the static pressure before recommending anything. If it is high, a correctly sized pressure reducing valve protects the whole house rather than one appliance. If it is normal, we will not sell you a valve you do not need. Homes on tank or bore water can also get hammer from a pump that switches on and off too often, which points to the pump or its pressure vessel instead.

How we stop it

We start by recreating the noise. We run each fixture and appliance, shut it off sharply and listen, then check the pressure at the toby or the nearest outside tap. From under the house or in the ceiling we look at how the pipe is fixed and where it touches framing.

The fix follows the cause. Loose runs are re-clipped with rubber-lined clips, and cushioned packers or grommets go where pipe passes through timber. Where one appliance is the trigger, we fit a water hammer arrestor on its supply, just upstream of the valve. An arrestor holds a sealed cushion of air or gas behind a piston that soaks up the surge. If a worn tap cartridge or a chattering cistern valve is to blame, we replace that part, and our tap and mixer repairs team can do it on the same visit.

Shaking pipes and earthquake country

Wellington sits on active faults, including the Wellington Fault that runs through the city and up the Hutt Valley. Pipes that are loosely held can move a lot more than they should when the ground shakes, and joints that are already being worked by water hammer are the ones most likely to give. Re-clipping a noisy run is a small job that also leaves the pipework better secured, which is worth doing anyway.

Water hammer is not only an old-house problem. In newer homes and townhouses, pipe in walls and between floors can carry noise into bedrooms if it was fixed tight to studs without cushioning. A new laundry or kitchen can also bring fast-closing valves into a house whose pipework was never set up for them. If you are booking a dishwasher or washing machine install, ask us to fit an arrestor at the same time.

What affects the cost

The final price depends on:

• How many fixtures or appliances are causing the noise
• Access to the pipe, from an open subfloor to a tight crawl space on a hill section
• Whether the fix is clips and packers, an arrestor or both
• Whether a pressure reducing valve is needed for the whole house
• Replacing worn tap cartridges or cistern valves on the same visit

Why Choose Cheeky's Plumbers for Water Hammer

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Water Hammer Across Wellington

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