Water Hammer Christchurch

Water hammer is the bang, knock or shudder you hear when moving water is stopped suddenly. Water is heavy and does not compress, so when a valve snaps shut the flowing column has nowhere to go. A pressure spike runs back along the pipe, and if that pipe is loose it slaps against a joist, a stud or another pipe.

It is worth fixing rather than living with. Repeated shocks loosen joints, wear out appliance valves and flexible hoses, and can eventually open a leak somewhere you cannot see. Most cases have one clear cause and a tidy fix, and finding that cause is where we start.

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 Christchurch

• 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

Different sounds point to different causes, so note when the noise happens before you call. It helps us find the trigger faster:

• One loud bang when the washing machine or dishwasher stops filling
• Knocking when someone flicks a lever mixer off quickly
• A rapid rattle from a toilet cistern as it finishes refilling
• Thudding under the floor that seems to come from the whole house
• A hum or groan while a tap is running
• Noise that only started after a new appliance went in

Common causes in Christchurch homes

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 typical sources. Modern appliances shut their inlet valves in a fraction of a second, which is why a house that was quiet for decades can start banging the day a new dishwasher arrives.

How the pipes are held is the other half. Many Christchurch bungalows and mid-century homes have copper or galvanised pipe under suspended timber floors, held by a few clips that have rusted or dropped off. Homes that had floors relevelled or piles replaced after the 2010 and 2011 earthquakes can also have pipe runs that were disconnected and refixed during the work. A surge that would pass silently through a well-clipped pipe becomes a bang when the pipe can swing into a joist. Level notes water hammer mostly occurs in metal pipe, though plastic pipe can be affected too.

How It Works

How we stop it

We start by making the noise happen. We run each fixture and appliance, shut it off sharply and listen, then measure the static pressure at the meter. From under the house or in the ceiling we check how the pipes are fixed and where they touch the framing.

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

When pressure is part of the problem

Christchurch's town water is pumped from deep wells into the network, and the council feeds hill suburbs such as Cashmere and the Port Hills from reservoirs and tanks to keep pressure steady. Pressure at your tap still depends on where the house sits in the network, so we measure it rather than guess. Higher pressure and faster flow make every surge stronger.

If the reading is high for your fittings, a properly sized pressure reducing valve treats the whole house rather than one appliance. If your pressure is normal, we will not sell you a valve you do not need. Lifestyle blocks on tank water in Selwyn and Waimakariri can get the same banging from a pump that stops and starts too often, which points us to the pump or pressure vessel instead.

What affects the cost

The final price depends on:

• How many fixtures or appliances are causing the noise
• Access to the pipes, from an open subfloor to a tight crawl space or finished ceiling
• 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 inlet valves at the same time

Noise in new builds and renovations

Water hammer is not only an old house problem. New homes in growing areas like Halswell, Rolleston and Pegasus can carry pipe noise into bedrooms if the pipes were fixed tight to studs without cushioning. Many rebuilt homes on TC2 and TC3 land sit on concrete slabs or engineered foundations, so pipes run through walls and ceilings rather than an open subfloor, and access needs planning.

After a renovation, a new laundry or kitchen can bring fast-closing valves into a house whose pipework was never set up for them. If you are planning a dishwasher or washing machine install, we can fit an arrestor at the same time and save a second visit.

Why Choose Cheeky's Plumbers for Water Hammer

Water Hammer FAQs

Water Hammer Across Christchurch

Our water hammer team works in every Christchurch suburb. Find your local plumbers:

Related Services

See all plumbing services or every service we offer.