Once you know you have a leak, you'll need to hire a plumber. But how do plumbers find leaks? Plumbers use moisture meters and determine the area of the wall with the highest moisture levels. Sometimes, leaks are located using infrared cameras, which point out the coolest (and wettest) areas behind the walls.

For the most precise leak detection, plumbers use video pipe inspection equipment. These are small cameras mounted on long flexible fiber optic cables. Plumbers can insert these in faucets and other plumbing outlets to detect leaks.

You'll pay between £80 – £1,600 for leak detection in the UK. On average though, you can expect to pay around £500. But this depends on a range of factors such as: Where you're based.