TL;DR
- A water meter that keeps moving when every tap and appliance is off means water is passing through your supply somewhere on your side of the system.
- The most common causes are a running toilet, a dripping tap, a leaking hot water system, a hidden pipe leak, or an underground supply line fault.
- A two-step isolation test tells you whether the leak is inside the house or in the underground pipe between the meter and your home.
- A hidden leak can run for months before you notice it — and it will show up on your Sydney Water bill long before it shows up on your walls or floor.
- If you can’t find the source yourself, call a licensed plumber. Don’t leave a moving meter to sort itself out.
The meter is not guessing
Your water meter records every litre that enters your property from the street main. When everything inside is off — taps, dishwasher, washing machine, irrigation — the meter should sit completely still. If it’s ticking over, spinning, or the dial is creeping around, that means water is moving through your supply right now.
It’s not a meter glitch. It’s not pressure fluctuation. It’s water going somewhere it shouldn’t be.
The good news: you can narrow down where in about five minutes, without tools, before you call anyone.
The two-step isolation test
This is the most useful thing you can do before picking up the phone. It tells you whether the leak is inside the house or underground between the meter and your home.
Step 1: Make sure everything is actually off
Go through the whole property. Kitchen taps, bathroom taps, shower mixers, laundry taps, outdoor taps, toilets, washing machine, dishwasher, fridge water connection, any irrigation controller or pool top-up system. Give a recently flushed toilet cistern a minute or two to finish refilling before you check the meter.
Once everything is genuinely off, watch the meter’s flow indicator — the small dial, star, or needle on the face — for about two minutes. If it’s moving, you have a leak somewhere.
Step 2: Close your internal stop tap and check again
Your internal stop tap (also called your main shutoff valve) is usually near the front boundary, in a meter box at the footpath, or inside the house near where the supply enters. Close it fully, then go back and watch the meter.
- Meter stops moving: The leak is inside the house — somewhere in the pipework, fixtures, or appliances past that valve. That’s your starting point.
- Meter keeps moving: The leak is most likely in the underground supply pipe between the meter and your home. That’s a different job, and it needs a licensed plumber with leak detection equipment.
If you’re unsure where your main shutoff valve is, our guide on finding your main water shut-off valve in Sydney covers all the common locations by property type.
The most common causes — and how to spot them
1. A running toilet cistern
This is the single most frequent cause of unexplained meter movement in Sydney homes. A worn flush valve seal, a faulty fill valve, or a float set too high can let water trickle continuously from the cistern into the bowl. It’s often silent — you won’t hear it unless you listen at the bowl.
Quick check: take a sheet of dry toilet paper and press it flat against the back of the bowl, just above the waterline. Leave it for 30 seconds. If it gets wet without a flush, the cistern is leaking into the bowl.
A running toilet can waste thousands of litres a week. It’s one of the cheapest faults to fix and one of the most commonly ignored.
2. A dripping tap or leaking showerhead
Even a slow drip from a tap keeps the meter moving. If the tap is dripping into a drain, you may not notice the water loss at all — just the bill. Check every tap in the house, including outdoor taps and the laundry, and look for any slow weeping around base seals or under sink connections.
3. A leaking hot water system
Hot water units have several points where water can escape: the pressure relief valve, the inlet or outlet connections, the tank body itself, or the overflow pipe. Some of these drip to a drain and are easy to miss. Check around the base of the unit and look for moisture, staining, or a constantly weeping overflow pipe.
4. A hidden pipe leak inside the house
Leaks inside walls, under floors, or above ceilings don’t always produce visible damp straight away. A slow pinhole leak in a copper pipe can run for months before the damage becomes obvious. By then, the meter has been recording it the whole time.
Signs to look for: unexplained damp patches, paint bubbling on walls or ceilings, warm spots on a tiled floor (often a hot water line leak), musty smells in a room that stays closed, or a water bill that keeps creeping up with no change in your habits.
5. An underground supply pipe leak
If the meter keeps moving even after you close the internal stop tap, the fault is likely in the underground pipe running from the meter to the house. These leaks are harder to detect visually — you might see a soggy patch of lawn, unusually lush grass in one strip, or soft ground near the path — but often there’s no surface sign at all.
Underground leaks need proper leak detection equipment: acoustic sensors, pressure testing, or tracer gas. You can’t find them reliably by digging around. Our article on signs your Sydney home has an underground water leak covers what to look for in more detail.
6. An automatic system using water on a schedule
Before assuming the worst, check whether anything automated is running. Irrigation controllers, pool top-up systems, rainwater tank changeover valves, or even a fridge water line can use water without you realising. Check that any irrigation controller is genuinely off and not mid-cycle, and that the pool auto-fill isn’t running.
7. A faulty meter (rare, but possible)
In unusual cases, air pockets or pressure fluctuations in the street main can cause a meter to register movement when no water is actually being used. This is uncommon and usually shows as very slight, inconsistent movement rather than steady spinning. If a licensed plumber has checked your entire property and found no leak, this is worth raising with Sydney Water directly.
The two-minute meter reading test
If you’re not sure whether the meter is moving or just hard to read, do this: note the exact reading on the meter display, including the last decimal digit if visible. Don’t use any water for two hours. Come back and read it again. If the number has changed at all, water has moved through your supply.
For a faster check, look for the small flow indicator on the meter face — a star, dial, or red triangle. Even a slow leak will keep it moving.
Whose pipe is it? The responsibility question
In Sydney, the water main in the street belongs to Sydney Water. The meter itself is owned and maintained by Sydney Water. But the supply pipe from the meter to your house — and everything inside the house — is your responsibility as the property owner.
So if the leak is between the meter and your home, or anywhere inside, the repair cost is yours. If the leak is in the street main before the meter, that’s Sydney Water’s problem. Our article on water leaks before or after the meter explains exactly where the responsibility line sits.
What about the water bill you’ve already been hit with?
If a hidden leak has been running for weeks or months and you’ve received a high Sydney Water bill as a result, you may be able to claim some of it back.
Sydney Water offers a Hidden Leak Allowance: a credit of 50% of the water usage charge for the most affected quarter, when a licensed plumber or qualified technician finds and repairs a leak you could not see or hear. You apply within a year of the repair, with the plumber’s invoice, and a property can get one allowance every five years.
The leak must be genuinely hidden — one you didn’t know about and couldn’t see or hear. Visible leaks such as dripping taps, toilet cisterns, appliances, or damp soil don’t qualify.
It’s one of the most under-claimed credits in NSW, and it’s worth asking about when you get the repair invoice.
What a plumber actually does to find the source
When you’ve run through the checks above and still can’t find where the water is going, a licensed plumber with leak detection equipment is the next step. The process usually starts with pressure testing to confirm the system is losing water, then moves to acoustic detection — listening through walls, floors, and ground for the sound of water escaping — and thermal imaging to pick up temperature differences caused by a wet area behind a surface.
For underground leaks, tracer gas is sometimes used: a harmless gas is introduced into the pipe and a sensor detects where it escapes at the surface. It’s precise and avoids unnecessary digging.
The goal is to find the exact fault location before opening anything up. That keeps the repair contained and gives you a clear written record for your insurer and any Sydney Water claim. For a full breakdown of the methods plumbers use, see our guide to how plumbers find hidden water leaks.
What to do right now
If your meter is moving with everything off:
- Run the two-step isolation test to work out whether the leak is inside or underground.
- Check the toilet cisterns first — they’re the most common culprit.
- Look at the hot water unit, under sinks, and at any outdoor taps.
- If you can’t find it, or the meter keeps moving even with the internal stop tap closed, call a licensed plumber. Don’t wait for the next bill to confirm it.
Jasco Plumbing handles leak detection across Sydney — same-day where possible, licensed plumbers, and a fixed price before any work starts. Call us or book online and tell us what you’re seeing at the meter.