How to Tell If You Have a Water Leak Under the Floor

The most common warning signs

Under-floor leaks rarely announce themselves with a puddle. Instead, you tend to get a cluster of smaller clues that build up over days or weeks. If you notice two or three of these together, it is worth investigating properly.

Pay particular attention to warm spots on the floor, which usually point to a leak on the hot feed or central heating pipework buried in the screed.

• A patch of floor that feels warm or damp underfoot
• A musty, damp smell that will not shift, often near skirting
• Tiles lifting or laminate cupping and swelling at the edges
• The sound of running water when every tap is off
• Unexplained mould appearing low on walls or in corners

Do the meter test

Your water meter is the simplest home check available. Turn off every tap and appliance that uses water, then take a photo of the meter reading. Wait one to two hours without using any water and read it again.

If the numbers have moved, water is escaping somewhere on your supply. This does not confirm the leak is under the floor, but it tells you a leak exists and is worth chasing. For heating leaks, keep an eye on your boiler pressure gauge instead, as a slow drop often means water is escaping from buried heating pipes.

Why under-floor leaks are hard to trace

Water does not always surface where it escapes. A pipe can leak under the kitchen yet the damp appears in the hallway, because water tracks along the path of least resistance beneath the screed or subfloor. This is why lifting a random floorboard or hacking up tiles rarely finds the source and usually makes the mess worse.

A specialist uses non-invasive methods such as thermal imaging, acoustic listening equipment and tracer gas to pinpoint the leak to within a small area before any floor is disturbed. In older Derbyshire properties with solid concrete floors or a mix of copper and older pipework, this targeted approach saves a great deal of unnecessary damage.

What to do while you wait

If you suspect a leak, isolate the supply at the stopcock when the property is empty to limit further water loss. For a suspected heating leak, note the boiler pressure so you can tell an engineer how quickly it is dropping.

Avoid pulling up flooring yourself. A proper leak detection visit in the Derby area typically costs somewhere in the region of £200 to £400 depending on access and the method needed, and it protects your floor from guesswork. Keep any photos of damp patches and meter readings, as they help speed up the diagnosis and may support an insurance claim under trace and access cover.