“Leak detection without building works” means locating the point where an installation is leaking, without chiselling or opening trenches to search for it. It is achieved by combining tests that confirm the leak and narrow down the section (pressure, sectorisation) with equipment that locates it from outside (geophone, tracer gas, camera, thermography). No single technique works for everything: each one needs certain conditions and has its limits, and choosing the right order saves time and trial openings. This is the comparison, with what each technique does and what it does not.
It is worth separating two things that are often mixed up: locating without building works is almost always possible; repairing without building works depends on the break, and we cover that at the end.
The usual order of a diagnosis
- Confirm that there is a leak and in which part of the installation. With all consumption points closed, the meter should not move. If it moves, intermediate valves (cold water, hot water, heating, irrigation, pool) are closed to see which one it stops at. In closed circuits, such as heating or pools, each section is isolated and pressurised with water, air or nitrogen: whichever does not hold pressure is the one losing. This step does not locate anything, but it avoids searching the whole house for something that sits on a single circuit.
- Locate the point with the technique suited to that section: tracer gas in the drained branch, geophone listening if the pipe is under pressure and transmits sound, camera if it is a drain, underwater inspection if it is a pool basin. It is usual to use two: one to locate and another to confirm.
- Open only where necessary. The aim of the diagnosis is for the opening, if one is needed, to be a single one in the right place.
That is the general outline of the sector, and the table below describes the techniques that exist, whether or not we use them. Our usual procedure in a home or a community is more specific.
How we do it
First we check the installation and sectorise it by closing valves, with pressure tests and probes to identify the branch that is losing. Then, when the branch can be emptied and charged, we fill it with tracer gas and trace its whole route with the detector. When the point appears, we confirm it before marking it with the supporting techniques the case allows: normally the geophone and, in some jobs, the thermographic camera. Everything is recorded in a report with photographs. If the branch cannot be emptied and charged, for example because the water is cut off, the order changes and we start with listening.
Comparison of techniques
| Technique | What it is for | What it needs | Limits |
|---|---|---|---|
| Pressure / tightness test | Confirm whether a section or circuit is losing and how much. | Being able to isolate the section (valves or plugs) and charge it with water, air or nitrogen. | It does not locate the point; it only shows which section fails. |
| Geophone (acoustic listening) | Locating leaks in pressurised pipes: cold and hot water, heating, service connections, pressurised pool circuits. | Pressure in the pipe, a material that transmits sound (metal is better than plastic), hard paving and little ambient noise. | Useless without pressure (drains, downpipes). Loses effectiveness in plastic, loose soil, at depth and with noise. |
| Acoustic correlator (sector technique; not part of our usual procedure) | Locating the leak on long network runs (communities, housing estates, service connections). | Two contact points on either side of the leak; knowing the material, diameter and length. | The same limits as the geophone; precision drops if the actual material or length differ from the plans. |
| Tracer gas | Locating leaks that do not make a sound: plastic pipes, underfloor heating, buried or unpressurised runs, pools. | Emptying the section of water and filling it with a tracer gas; access for injection (a tap will do); a surface through which the gas can escape. | The gas can travel through joints or voids and emerge away from the real point; impermeable membranes or very dense floor coverings hold it back; outdoors the wind disperses the reading. |
| Thermography | Seeing temperature differences at the surface: route of hot water pipes, underfloor heating, damp areas that cool through evaporation. | A real thermal contrast between the pipe or the moisture and its surroundings. | It does not see the leak or the water: it sees temperatures. A thermal bridge or sun on a wall can look like damp. It is a supporting technique. |
| Inspection camera (video inspection) | Seeing inside drains, downpipes and collectors: cracks, displaced joints, roots, crushed sections. | Sufficient diameter and an access point (inspection chamber, access cover, trap). | Not suitable for small-diameter pressurised water pipes. It shows the defect from inside; to find where it is on site, the camera head is located with a probe. |
| Locator probe | Following the route and depth of a pipe or of the camera head from the surface. | A transmitter in the pipe or on the camera and a receiver above. | It only locates the pipe or the camera head, not the leak. |
| Underwater inspection | Locating leaks in the pool basin: joints, light fittings, skimmer mouths, jets, cracks in the lining. | Pool full. Suspect points are checked with coloured tracers and a camera; a diver when the job requires it. | Not useful for the buried circuit pipes, which are checked by pressure. |
How the technique is chosen for each case
Water pipe built into a home
First the meter and valves are used to confirm which network is losing (cold, hot, heating). From there there are two routes that the sector combines depending on the case: listening with a geophone, which works better the more metallic, pressurised and quiet the installation is, and tracer gas, which does not depend on the leak making a sound and is the one we use as the main technique once the branch has been sectorised, with the geophone for the initial sweep or confirmation. Thermography can help follow the route if the pipe carries hot water.
Underfloor or heating circuit
The symptom is a pressure gauge reading that drops and needs topping up. The circuit is pressurised to confirm the loss and, if there are several circuits, the faulty one is identified. Thermography shows the route of the tubes and sometimes the anomalous area; tracer gas locates the point, because the tube is plastic and often does not make a sound.
Service connection or buried pipe in the garden
The route is followed with a probe, listening with a geophone at contact points and on the ground; if the material is plastic or the ground absorbs sound, the section is emptied and tracer gas is used. On long network runs, the sector also uses the correlator to narrow down the distance before listening at the surface.
Drain or downpipe
There is no pressure, so neither geophone nor correlator. A tightness test of the section is carried out and the camera is inserted to see the joint or crack; the probe indicates from above where the camera head is.
Pool
The work is carried out with the pool full. First the tightness of the skimmer, delivery and floor-cleaner pipes is checked separately under controlled pressure to isolate the section with the break; if the circuit holds, the problem is in the basin and the light fittings, floor drain, jets, joints and walls are checked with tracers and a camera. Before calling, the bucket test with the pump on and off already points towards either the circuit or the basin.
Four wrong ideas about leak detection without building works
- “Tracer gas always finds the leak.” It is very effective, but the gas seeks the easiest path upwards and may escape through a floor joint some distance from the real point, or be held back under an impermeable membrane. It is interpreted, not read.
- “Thermography sees the leak.” It sees temperatures. It helps orient in hot water, underfloor heating and damp, but a cold patch in the image is not a leak until it is confirmed another way.
- “A camera sees any leak.” Only in pipes the camera can pass through, that is drains and downpipes. Supply pipes are not inspected that way.
- “Without building works” also means you do not have to open anything to repair. Locating without building works is almost always possible; repairing depends on the break.
Repairing without building works: when it is possible and when it is not
Once the leak has been located, there are repairs that avoid traditional works: injecting resins and polymers that seal the crack from inside in pool circuits, or the internal lining of downpipes and collectors, which creates a new pipe inside the old one without replacing it. It is not always possible: when a pipe is collapsed or crushed it has to be opened, and for many isolated breaks in supply pipes the reasonable option is a small opening at the located point and replacing the section. In several pool resin jobs, what has forced us to open has been sections that the camera and equipment could not pass: several consecutive bends, a mix of rigid and flexible pipe, or a kinked flexible hose. In those cases a small opening is made at that point and the rest of the circuit is rehabilitated from inside. A good diagnosis tells you in advance which of the two cases yours is. If you want to know what options exist, we detail them in repairing pipes without building works.
What to expect from a technician's visit
A serious diagnosis starts by asking about the symptoms (meter, damp, bill, gauge, pool level) to choose the equipment to bring, continues with the tests the case requires (not all in every job) and ends with a report that states where the leak is, which tests were carried out and which repair is recommended. That technical report is the document you can provide to the insurer or the community of owners. If you want us to look at your case, you can contact us about it through our water leak detection, and if yours is a pressurised pipe and you want to understand listening in depth, you have the guide on how a geophone works.
