How to find a water leak in your house
Tell our free leak finder where you’re seeing water. It asks a few quick questions, then shows the likely sources, the check for each one and who fixes it.
Where is the leak coming from?
Tap where you see water, or pick the place that matches yours. The finder asks two or three questions and lists the likely sources in order.
Water or damp you can see
How to find a hidden water leak: three checks
Do these in order. Each one rules out a big part of the house, and none of them needs tools. No water meter? Start at check 3 and the fitting checks in the guides. An older heating system fed from a loft tank may have no pressure gauge.
Read the water meter
Turn off every tap and appliance and wait until nothing is filling. Read the meter, wait 30 minutes, read it again.
Numbers moved: water is escaping. No change: no leak on the mains side at the moment.
Close the stop tap
With everything still off, close the internal stop tap, usually under the kitchen sink, and watch the meter.
Still moving: the leak is between the meter and the stop tap, usually on the supply pipe. Stopped: it is inside the house.
Watch the boiler pressure
Note the pressure gauge last thing at night with the heating off, and again in the morning.
It dropped: the heating system is losing water. Steady: the heating is probably not the source.
The meter and stop tap checks follow water company guidance, for example Southern Water: how to find and fix leaks.
Common household leaks you can see
The leaks people search for most often start at a fitting. Each guide shows where that fitting leaks, the test that confirms it, and who fixes it.
Boiler
Where it showsA puddle under the boiler, or drips outside from a small copper pipeUsuallyThe pressure relief valve, a pipe joint, or a part inside the caseRadiator
Where it showsA wet patch or crusty stain under one endUsuallyA valve nut or spindle, the bleed valve, or a corroded radiatorToilet
Where it showsWater round the base, or a trickle into the pan that never stopsUsuallyThe pan connector, the base seal, or the cistern valvesShower
Where it showsWater outside the tray, or a stain on the ceiling belowUsuallySeals and grout, the tray waste, or pipes behind the tilesKitchen sink
Where it showsA wet cupboard floor or a swollen base under the sinkUsuallyTap hoses and valves, the plughole seal, or the trap joints
Signs of a hidden water leak
If every fitting is dry and the water keeps coming, the leak is probably on a pipe you cannot see: buried under a solid floor, inside a wall, above a ceiling or underground outside. These are the usual signs.
- The meter moves with every tap and appliance off.
- The boiler keeps losing pressure, no radiator is dripping and the small copper pipe outside is dry.
- A patch of floor feels warm, or a damp patch keeps growing in dry weather.
- You can hear water running when nothing is on.
- The water bill has jumped and you cannot explain it.
Hidden leak? Call ADI Leak Detection
When the water is coming from a pipe inside a wall, under a floor or underground, ADI traces it with equipment such as acoustic listening, thermal imaging and tracer gas, and marks the leak on site before any repair is discussed.
- 25 leak investigation engineers, around 5,000 jobs a year across England, Scotland and Wales
- A fixed price quoted before you book, and a written report you can give your insurer
- Rated 4.7 on Trustpilot from 1,624 reviews
ADI figures as of September 2026, from ADI's About page. Trustpilot rating read 28 September 2026.
Questions about finding a water leak
How do I find a water leak that I can’t see?
Start with the water meter. Turn off every tap and appliance, make sure nothing is filling, and read the meter twice about 30 minutes apart. If the numbers move, water is escaping somewhere.
Then close the internal stop tap and watch the meter again. If it still moves, the leak is on the pipe between the meter and the stop tap. If it stops, the leak is inside the house, and the leak finder helps you narrow it down.
How can I tell where my water is leaking from?
Work back from where the water shows. Water runs downhill and along pipes, joists and tile joints, so a stain is often some way below or beside the real source. Look at what sits directly above the stain, notice when it gets worse (after a shower, after rain, when the heating is on), and test one fitting at a time.
How much does it cost to trace a water leak?
It depends on where the leak is and how many pipes might be involved. A drip under a sink is often a quick plumbing job. A hidden leak under a floor or in a wall needs specialist detection equipment and takes longer.
This site does not publish prices. ADI Leak Detection quotes a fixed price for an investigation before you book, so you know the cost before anyone arrives.
Is a water leak an emergency?
Treat it as one if water is near electrics, a ceiling is bulging, or water is pouring rather than dripping. Turn off the water at the stop tap, which is usually under the kitchen sink, and keep away from wet electrical fittings.
A slow stain or a meter that creeps is not an emergency, but it is worth finding quickly. Hidden leaks keep soaking floors and walls until someone finds them.
Who is responsible for fixing a leak?
Inside your home, and usually on the supply pipe on your property, it is the owner. If you rent, tell your landlord straight away. If you live in a flat and the water comes from above, tell your neighbour and the managing agent. If water is coming up in the street, report it to your water company.