Do the meter test first
Turn off every tap and appliance in the house, including the ice maker and any irrigation timer. Then go and read your water meter, including the small dial that measures fine flow.
Wait thirty minutes without using any water and read it again. If it has moved at all, you have a leak somewhere between the meter and your fixtures.
The usual culprits
A running toilet is the most common and the most invisible. The water goes straight down the pan with no sound and no puddle. Put a few drops of food colouring in the cistern, wait twenty minutes without flushing, and check the bowl. Colour in the bowl means the flush valve is leaking.
After that: a dripping mixer, an irrigation solenoid that is not closing fully, a relief valve on the hot water unit weeping constantly, and a leaking pipe under a slab or in a wall cavity.
Signs of a concealed leak
A warm patch on the floor. A section of garden that stays green through a dry spell. Paint bubbling low on a wall. A faint hiss when the house is silent.
Any of those with a moving meter is worth having found properly rather than opened up speculatively.
Finding it without demolition
Acoustic listening equipment and moisture meters narrow a concealed leak down to a small area before anything gets cut. That turns a guess into a targeted opening the size of a dinner plate.
It is worth doing this properly. The cost of locating a leak accurately is almost always less than the cost of repairing an inaccurate hole.
Written by the team at Adlington Plumbing. Licensed plumbing and gas fitting across Newcastle, Lake Macquarie and the Central Coast. Licence 384065C.