How To Tell If You Have a Hidden Water Leak

The ten-minute meter test

Your water meter can tell you definitively whether water is escaping somewhere. Turn off every tap and water-using appliance — inside and out, including the washing machine, dishwasher, evaporative cooler and irrigation. Then go to the meter at the front of the property and watch it.

If any dial or number is still creeping after 10–15 minutes with everything off, water is flowing somewhere it shouldn't be. Take a photo of the reading, wait an hour without using water, and photograph it again — the difference is your leak, measured in litres.

Warning signs around the house

• A water bill noticeably higher than the same period last year, with no change in habits
• Damp patches, bubbling paint or bulging plaster on walls or ceilings
• Mould or a persistent musty smell in one area
• Warm patches on a concrete floor — often a hot water pipe leaking under the slab
• The sound of running water when everything is off
• A patch of garden that stays green and soggy while the rest dries out
• Low water pressure that has developed gradually

Where hidden leaks hide

The usual suspects are pipe joints inside walls, hot water lines under concrete slabs, the underground water service between the meter and the house, and toilets leaking silently from cistern to bowl.

That last one is worth testing while you're at it: put a few drops of food colouring in the cistern and wait 15 minutes without flushing. Colour appearing in the bowl means the outlet valve is leaking — a cheap fix that can be wasting hundreds of litres a day.

What to do if the meter says yes

Don't start pulling up floors. Modern leak detection can narrow a leak's location without destructive digging or demolition, which means the repair disturbs as little of your home as possible. The sooner it's found, the less water — and plaster, and flooring — you pay for.