My Water Bill Tripled — Turns Out It Was a Burst Pipe Under the Slab
I got a call to a terrace in Cremorne where the water bill had tripled. The owner thought they had a leaky tap. Turned out the copper supply pipe under the concrete slab had pinhole corrosion. Here's what to do when your water main goes.
The call that could have cost a fortune
I got a call as an emergency plumber to a terrace in Cremorne last week. The water bill had tripled and the owner thought they had a leaky tap. They'd been ignoring it for months. Turns out the copper supply pipe under the concrete slab had pinhole corrosion — tiny holes you can't see until the damage is done.
"I just thought the tap was dripping," they said. It wasn't the tap. It was the pressurised water main leaking under the slab.
We ran a water pressure test to confirm the leak was in the supply line — which can affect your hot water system if left unchecked — then did a trenchless re-routing — ran a new pipe underground without digging up the whole floor. In older homes across Cremorne and Neutral Bay, we see copper pipes from the 70s that develop this kind of pinholing. In Freshwater, where homes are newer with poly pipes, we see different issues — fittings that blow off or joint failures.
What to do when you suspect a water main leak
- • Check your water meter — if it's spinning when all taps are off, you've got a leak somewhere
- • Look for damp patches on floors, walls, or unusually green grass over your pipe lines
- • Listen for running water sounds when nothing is turned on
- • If your bill has jumped for no reason, don't assume it's a tap — get a pressure test done
- • Turn off the mains at the boundary trap if you suspect a burst and call a plumber straight away
Why different suburbs have different pipe problems
In Cremorne and Neutral Bay, those older homes were built with copper supply pipes. Copper is great stuff — until it's been in the ground for 40+ years and starts getting pinhole corrosion from soil acidity or water chemistry. We replace these regularly.
In Freshwater and the newer coastal developments, they used poly pipe (polyethylene). It doesn't corrode, but it's more prone to damage from ground movement or if someone drives a peg through it. Different materials, different problems, but the fix is the same: find the leak, isolate it, and run a new pipe.
The honest truth
Water main leaks don't fix themselves. The longer you leave them, the more damage they cause — to your slab, your floors, your walls. I'll come out, run the tests, and give you a fixed price to fix it. If it's a simple valve replacement, I'll tell you. If you need a full re-route, I'll show you why. No pressure, no upsell.
Think you've got a water main leak?
I'll run a pressure test and find the leak fast. Upfront pricing, same-day service across the Northern Beaches.
Frequently asked questions
Where is the water shut-off valve in a strata unit or apartment?
In most Northern Beaches apartments and strata units, the individual shut-off valve is inside the unit — under the kitchen sink or in the laundry. The building's main valve is in a common area, often a basement or utility room, and should only be operated by the strata manager or building maintenance. Know where your individual valve is before you need to find it in the dark.
What if the valve is stuck or will not turn?
Do not force it — you can snap the stem or damage the pipe. Apply penetrating oil (WD-40 or similar) to the valve stem and wait 10 minutes before trying again. If it still will not turn, call a plumber. Some older Northern Beaches properties have valves that have not been turned in decades and will need professional replacement.
How do I turn the water off if I cannot find the meter?
If the meter box is buried under landscaping, overgrown, or completely inaccessible, call us. We can install a new shut-off valve at a more convenient location — usually near the front of the house where the supply pipe enters the building. This is a common issue on the Northern Beaches where older properties have had garden renovations that covered the meter.
Should I turn the water off at the mains before going on holiday?
Yes — it is one of the best things you can do to prevent water damage while away. A burst pipe in an unoccupied home can run for days. Simply turning off the mains eliminates that risk. If you have an automatic irrigation system or pets that need automatic watering, leave the mains on but turn off the individual isolation valves to each appliance.
Related reading
- What to Do If a Pipe Bursts (Step-by-Step)— Once the water is off, here is what to do next.
- What Counts as a Plumbing Emergency?— Know when to turn the mains off vs when to wait.
- Signs You Need Emergency Plumbing Services— Recognise the situations that require urgent action.
- Emergency Plumber Cost: What to Expect for After-Hours Callouts— How much you will pay if the valve issue escalates.
- Water Leaking Through Ceiling? Causes and First Steps— What to do if turning off the mains was too late.