How Leak Detection Works, Step by Step

It starts with a call or a message. We ask what you have noticed, such as a boiler losing pressure, a meter turning with everything off, a warm patch or a damp patch that keeps coming back. We ask about the age of the house, the floor types and the heating. From that we agree a fixed price before we start and book a slot, and same-day and next-day surveys are usually available. Before we arrive, leave the heating on if it is a heating leak and clear the area around the stop tap and the boiler. Note down when the symptoms happen and anything that makes them worse.

On arrival we work out which system is leaking before we look for where. A meter test with every outlet off shows whether the cold mains is losing water. Turning off the internal stop tap and watching the meter again separates the outside supply pipe from the inside pipework. A pressure gauge on the central heating shows whether the heating circuit is losing pressure on its own. Where there is a damp patch to sample, water test strips tell mains water from heating water. This stage matters because each system needs a different method, and it stops time being spent listening for a leak on the wrong pipe.

The thermal imaging camera goes first on heating and hot water leaks. With the heating running it shows the pipe runs through the floor and plaster, and a leak appears as heat spreading away from the line. On live cold mains and supply pipes the acoustic ground microphone listens for water escaping under pressure through tiles, concrete and paving, and the reading peaks over the leak. Where the pipe is plastic, buried or too quiet to hear, it is drained and filled with a hydrogen and nitrogen tracer gas. A detector then follows the pipe to where the gas surfaces. That is a detection tool, not gas-safety work. A borescope looks into voids, and dye tests trace bath leaks.

Some of this means the water or the heating being off for short periods. A meter test needs every outlet off for a few minutes. A tracer gas test needs the pipe drained, and a pressure test needs the heating circuit closed while the gauge is read. We tell you before each one and put things back as soon as the reading is taken. Most home surveys take between two and four hours. Large properties, long buried supply pipes and underfloor heating take longer, and we say so before we start if that looks likely. Floors and walls are not opened to find the leak, only at the marked point if you ask us to repair it.

The survey ends with the leak marked, photographed and written up. The report sets out the symptoms, the systems tested, the methods and readings, the thermal images and the position of the leak on a plan, and goes to you as a PDF. If you want the repair done, we open that one spot, replace the pipe, refill and test, and add the repair photographs. We cannot promise to find every leak. Some are too small to register during the visit, and some are intermittent. If a leak cannot be located non-invasively, we say so, explain what has been ruled out and what the next step would be, rather than opening floors on a guess.