Plumber or leak detection: who to call for a leak under the floor or in a wall

There is water where it should not be, or the boiler keeps losing pressure, or the meter turns with everything off, and you are trying to work out who to call for a leak under the floor. The plumber you have used before, or a leak detection company you have never heard of. It matters, because calling the wrong one first costs you a visit, a wasted day and sometimes a hole in the wrong place.

This article gives you the honest split. What a plumber does well, what a leak detection engineer does that a plumber cannot, and which to ring first in each situation. It also covers what each route costs you in disruption, how the two work together on the same job, and what to look for when you search for leak detection near you.

What a plumber does, and does well

A plumber repairs and installs. If you can see the leak, or point to the fitting it is coming from, a plumber is the right call and usually the only one you need. A dripping radiator valve, a weeping joint under the sink, a split flexible hose behind the toilet, a cracked overflow: these are visible, reachable and fixed in a single visit.

A good plumber will also look at the obvious hidden places. They will take off a bath panel, check the trap under a shower, and look inside the boiler casing. What they do not carry is the equipment for finding a leak that leaves nothing to see, and most will tell you that themselves. When a plumber says the leak is somewhere under the floor and they cannot say where, that is the handover point.

What a leak detection engineer does

A leak detection engineer finds leaks that cannot be seen. The job is to pinpoint the break on a pipe that is buried, under a floor, inside a wall or in a screed, without opening everything up to look. It is done with equipment rather than guesswork: a thermal camera to see warm or cold water spreading behind a surface, a ground microphone to hear water escaping under pressure, and tracer gas to follow a pipe to the exact break.

The output is not a repair. It is a marked spot and a written report with photographs and readings. That report is what makes the repair small, because the plumber opens one place rather than several, and it is the document your insurer asks for under trace and access cover. We do not replace the plumber. We tell the plumber where to cut.

Who to call for a leak under the floor

If the floor is wet in one obvious place and you can lift a board or a hatch to see a pipe, call a plumber. If the floor is solid concrete, tiled or covered in fitted laminate, and the only evidence is a damp patch at the skirting, a warm spot underfoot or a boiler that keeps losing pressure, call a leak detection engineer first.

The reason is simple. A plumber faced with a solid floor and no visible pipe has one option: break the floor open where the leak seems likely and look. If the guess is wrong, the floor is broken in a second place. Under a tiled floor with underfloor heating that is an expensive way to search. A detection visit marks the point before anyone picks up a breaker.

Leaks under floors are most often on the heating circuit, because that is where the pipes run. With the heating hot, the thermal camera shows the pipe routes through the floor and the wider warm bloom where water has spread. If the camera is not conclusive, the circuit is drained and filled with tracer gas, and the detector is walked over the floor until it reads at the break.

Who to call for a water leak in a wall

A water leak in a wall is the same decision with a different surface. If the wall has a visible pipe run, an access panel or a boxed in section you can open, a plumber can look. If the wall is tiled, plastered or has a kitchen fitted against it, and the sign is a bubbling patch of paint or a damp line that comes and goes, it is detection work.

Walls hide two kinds of leak. Pressurised pipes, such as the cold feed to a bathroom or a heating flow and return, leak all the time and show on the meter or the boiler gauge. Waste and shower leaks only run when the fitting is used, so the damp comes and goes with the shower. Working out which you have is half the answer, and it decides which equipment we bring.

In a wall we use the thermal camera to see the spread of water behind the plaster, a moisture meter to map how far it has travelled, and for a shower or bath we run each fitting in turn and watch where the reading changes. The result is one tile or one panel off, not a wall stripped back to the brick.

What each route costs you in disruption

Think about the cost in time and mess rather than the invoice. The plumber first route works well when the leak is visible, because the whole thing is done in one visit. It works badly when the leak is hidden, because each exploratory hole is a day off work, a floor to make good and a room out of use, and the leak may still not be found.

The detection first route means one extra visit at the start. In return, the repair is a single opening in the right place, the making good is one patch rather than several, and the whole thing is usually over in days rather than weeks. For a leak under a tiled floor, in a screed, or on a supply pipe under a drive, the extra visit pays for itself many times over in floor and drive you do not have to dig up.

There is one more cost people forget. Every week a heating leak runs, more water goes into the floor, and every top up of the boiler is fresh water added to it. Every week a supply pipe leak runs, the water company records it on your meter. The faster the leak is pinpointed, the smaller both of those bills are.

How a plumber and a detection engineer work together

On most hidden leak jobs both are involved, and the order is detection then repair. We locate the leak, mark the spot, and hand you a report that says what the pipe is, where it is and how deep. Your plumber then opens that one place and fixes it. Some plumbers ring us directly when they reach the limit of what they can see, and some of our customers come to us on a plumber's advice.

If you already have a plumber you trust, keep them. Book the detection visit, give them the report, and let them do the repair. If you do not have one, ask us when we are there. We will tell you what the repair involves and whether it is a quick job or something that needs planning, such as replacing a full supply pipe or lifting a section of underfloor heating.

Searching for leak detection near me: what to check before you book

When you type leak detection near me into a search, you will get a mix of plumbers who mention detection, national call centres that subcontract the job, and specialist firms. Ring whichever you pick and ask four things. Do they carry thermal imaging, acoustic listening and tracer gas on the visit, or does one of those mean a second appointment. Do they give a fixed price before arriving. Is a written report included. What happens if nothing is found.

A leak detection specialist near me should be able to answer all four without hesitation. We carry all three methods on every visit, give the price on the phone, include the report, and work no find, no fee, so if we do not locate the leak you do not pay for the visit. We cover East Anglia and Greater London and can usually book you in within 24 to 48 hours.

A quick decision guide

If you are still unsure, use the list below. The dividing line is always the same: can anyone see the leak, or point to the fitting it is coming from. If yes, a plumber. If no, and the meter or the boiler gauge says water is going somewhere, detection first.

• Visible drip, reachable fitting: plumber
• Wet under a sink or bath with the panel off: plumber
• Damp patch, solid or tiled floor, no pipe in sight: leak detection
• Boiler loses pressure, every radiator and the boiler dry: leak detection
• Meter turns with the stop tap shut, nothing wet outside: leak detection
• Ceiling stain under a bathroom, comes and goes: leak detection, then plumber

Questions people ask