Look for persistently wet or lush ground, a hissing boundary stopcock and pressure loss indoors, then close the internal stopcock to confirm the leak sits outside the house. In Scotland the pipe from the boundary to your home belongs to you, not Scottish Water. Acoustic and tracer gas equipment can pinpoint the leak so only a small section of ground is dug.
How to Find an Underground Water Leak (and Who to Call)
Underground leaks are the ones nobody spots early. A supply pipe can leak under a garden or driveway for months, feeding the ground instead of flooding a kitchen, and in an unmetered Scottish home there is no water bill creeping up to give it away. Usually the first clue is a patch of ground that refuses to dry out.
The second problem arrives right after the first: whose job is it? Plenty of homeowners assume anything buried outside belongs to Scottish Water. Mostly, it does not. This guide covers how to find a water leak underground: the signs, the checks you can do yourself, how professionals pinpoint a buried leak without wrecking the garden, and who is responsible for putting it right.
In this guide
Signs the leak is underground
Outdoor evidence worth trusting
- A patch of grass noticeably greener or faster-growing than the rest
- Ground, gravel or monoblock that stays wet days after rain
- Moss thriving along one line across a driveway or path
- A sunken or soft strip of ground between the boundary and the house
- Water pooling or trickling near the boundary stopcock cover
- Reduced pressure at every tap while neighbours are unaffected
- A hissing sound at the boundary stopcock or where the pipe enters the house
Scotland’s weather complicates the reading. A wet corner of a Glasgow garden in November proves nothing. The same patch still wet after a dry fortnight in May is telling you something. Judge outdoor signs against the weather, not the calendar, and if the wet patch is your only symptom our article on wet patches in gardens and driveways digs into that specific case.
Who owns which pipe in Scotland
Before spending money, know whose pipe you are dealing with. Scottish Water’s leakage pages set out the split.
| Section of pipe | Where it runs | Who is responsible |
|---|---|---|
| Water main | Under the street | Scottish Water |
| Communication pipe | Main to your property boundary | Scottish Water |
| Boundary stopcock | At the edge of your property | Scottish Water |
| Supply pipe | Boundary to your home, under garden or driveway | The owner |
| Internal plumbing | Inside the property | The owner |
So the stretch under your lawn or monoblock is yours, and the obligation is real: under the Water (Scotland) Act, owners must repair supply pipe leaks, and Scottish Water can serve notice, carry out the repair and charge the owner if nothing is done, as Citizens Advice Scotland explains. Flats and older terraced homes often share a single supply pipe, which makes responsibility joint with the neighbours, per Scottish Water’s pipes FAQ. The full picture is in our guide to water pipe responsibility in Scotland.
How to find a water leak underground: DIY checks first
1. Confirm the leak is outside
Close your internal stopcock. If a hissing noise at the point where the mains enters the house continues, water is still moving through the buried supply pipe, which means the leak sits between the boundary and the wall. If all noise stops and boiler pressure holds, look indoors instead, starting with our guide on how to find a water leak.
2. Listen at the boundary stopcock
Lift the cover at the boundary (a screwdriver opens most) and listen. A constant hiss with everything in the house switched off is pressurised water escaping somewhere along the run. Early morning is best, before traffic noise builds.
3. Walk the pipe route
The supply pipe usually runs in a fairly straight line from the boundary stopcock to where the pipe enters the house, typically under the kitchen. Walk that line slowly and note soft ground, greener grass or damp joints in paving. Mark anything suspicious; patterns matter more than single spots.
4. If the property is metered, use the meter
Most Scottish homes are unmetered, but businesses and some newer homes do have meters. Take a reading last thing at night, use no water overnight, and read it again first thing. Movement on the dial with everything off confirms a leak on your side.
These checks tell you a buried leak exists and roughly where the pipe runs. What they cannot do is put an X on the ground accurate enough to dig against, and this is exactly the wrong place to guess.
Digging a driveway on a hunch is expensive twice: once to dig, once to reinstate. Call us on 07700 152 467 before anyone picks up a breaker.
How professionals pinpoint an underground leak
Two methods do most of the work on buried pipes, and they complement each other.
Acoustic detection uses a ground microphone moved along the pipe route. A pressurised leak makes a constant noise as water forces through the hole and hits the surrounding soil, and the sound peaks directly above the failure. On harder surfaces like monoblock and tarmac the sound carries well, which makes driveways surprisingly good places to listen. More detail in our acoustic leak detection guide.
Tracer gas takes over when the leak is too quiet, too deep, or the pipe is plastic, which carries sound poorly. The supply is drained and a safe hydrogen and nitrogen mixture is introduced. The gas escapes through the hole, rises through soil and paving, and a surface probe detects it. Between the two methods, plus electronic pipe tracing to map exactly where the run goes, most buried leaks can be located to a small dig window rather than a trench.
Locate first, dig second
The reason for all this kit is simple arithmetic. Excavating and reinstating a monoblock driveway costs serious money, and a speculative trench across it can cost more than the detection and repair combined. Locating first means the dig is one neat hole over the confirmed leak, the repair is quick, and the reinstatement is a patch rather than a rebuild. If your leak sits under a driveway specifically, trace and access insurance cover may pay for locating it and making good, which we explain in our trace and access guide.
Who to call and what happens next
If the leak is on Scottish Water’s side of the boundary, report it to Scottish Water and the repair is theirs. If it is on your side, the sequence is: get it located, get it repaired by a plumber or groundworker, and keep the paperwork. Scottish Water may offer help with supply pipe repairs through its supply pipe repair policy, described in its leaks and leakage FAQs, and if Scottish Water has already left you a card about a suspected leak, our article on what happens after a Scottish Water leak notice walks through the process.
Metered businesses have one more option: a Burst Allowance claimed through their Licensed Provider, which needs evidence including a detection or plumber’s report and meter readings after the repair, as set out by Scottish Water. MCR Leak Detection locates underground leaks for homes and businesses across Scotland, and every survey ends with a marked location and a written report.
Suspect a leak under your garden or drive?
We pinpoint underground leaks with acoustic and tracer gas equipment anywhere in Scotland, so the dig is one small hole in the right place. Available 24/7.
Frequently asked questions
How do I know if my underground leak is my responsibility or Scottish Water’s?
The boundary stopcock is the dividing line. Scottish Water owns the main, the communication pipe and the boundary stopcock itself. Everything from the boundary to your home, including pipe under your garden or driveway, belongs to the owner. On shared supply pipes, common in flats and older terraces, responsibility is joint.
Can an underground water leak go undetected for years?
Yes, particularly in Scotland. Unmetered homes get no bill warning, and a modest leak in free-draining ground may never surface. Long-running leaks often show up indirectly, through falling pressure, subsiding paving or a boundary stopcock chamber that is always full of water.
Will I have to dig up my whole driveway to fix a supply pipe leak?
Almost never. Acoustic correlation and tracer gas can locate most buried leaks to a small window, so the excavation is a single neat opening. In some cases a new pipe can be moled or rerouted with minimal surface disruption. Speculative trenching is the outcome detection exists to prevent.
Does home insurance cover an underground leak?
Often partially. Trace and access cover, included in most buildings policies, pays to locate the leak and make good the excavation. The pipe repair itself usually is not covered, and policies vary on damage caused by the escaping water. Check your policy documents before assuming either way.
What does it cost to find an underground water leak?
UK market guides put professional detection in the mid-hundreds of pounds, with ADI Leak Detection advertising surveys from £595 plus VAT and Checkatrade publishing similar ranges. Underground work sits at the upper end when pipe runs are long. Ask for a quote for your specific property.
Related reading
- Wet patch in the garden or driveway? Finding an outside leak
- Who is responsible for water pipes in Scotland?
- How to trace underground water pipes before you dig
- Acoustic leak detection: how engineers hear leaks underground
Or see our underground water leak detection service across Scotland.