Why is my water bill suddenly high?

A water bill that jumps without a change in household size or habits is a leak until proven otherwise. The good news is that you can confirm it yourself, for free, in under half an hour.

The meter test

1. 1Turn off every tap and appliance that uses water, including the dishwasher, washing machine and any irrigation.
2. 2Find your water meter and write down the exact reading, including the small dials or the last digits.
3. 3Do not use any water for twenty to thirty minutes.
4. 4Read it again. If the number has moved, water is going somewhere.

Where the water usually goes

• A leaking toilet. By a wide margin the most common, and often silent. Put a few drops of food colouring in the cistern, wait twenty minutes without flushing, and look in the bowl. Colour in the bowl means it is leaking.
• Dripping taps. A slow drip is far more water over a quarter than it looks.
• A leaking hot water system relief valve, which often discharges to a drain where nobody sees it.
• Irrigation, including a solenoid that is not closing fully.
• A concealed leak in a wall or under a slab, which is the expensive one and usually shows as unexplained damp, warm patches on a floor, or the sound of running water with everything off.

Toilet flappers and tap washers are generally within homeowner scope. Anything involving pipework in a wall, under a slab, or on the supply side is licensed plumbing work.