Six signs of a leak you cannot see

Not every leak arrives as a puddle. The ones inside walls and under floors tend to be found weeks later, by which point the damage is to plaster and floorboards rather than to a pipe.

What to look for

• A water bill that climbed for no reason. Compare it with the same quarter last year rather than with last quarter.
• A damp patch that keeps coming back after you have painted over it.
• A warm patch on the floor. Usually a heating pipe rather than a cold supply, and often the first sign of a leak under a screed.
• Running water you can hear when everything is turned off.
• Pressure that drops and needs topping up more often than it used to.
• A musty smell in one room, or in a cupboard against an outside wall.

The meter test

Turn off every tap and appliance that uses water. Read the meter, wait an hour without using any water, and read it again. If the number has moved, water is going somewhere. It is a blunt test, but it is decisive, and it costs nothing.

Finding it without taking the house apart

Once a leak is confirmed, the work is locating it before opening anything up. That is what leak detection is for: narrowing it down to a section of pipe rather than lifting a floor to find out.