How does acoustic leak detection trace a pipe leak under your floor?

Full transcript

George and Dave in conversation. Every word of the episode, exactly as recorded.

George

Welcome to the ADI Leak Detection podcast. I'm here with Dave from ADI Leak Detection, the UK's leading leak detection specialists, who's here to answer your questions and provide expert leak detection advice. Today's question comes straight from homeowners who've been told they've got a hidden water leak but can't see a drop anywhere. Dave, how does a specialist actually use acoustic equipment to follow a leak through a pipe?

Dave

Right, so the starting point is understanding that when water escapes a pressurised pipe, it creates noise. The water forces its way out through a crack or a joint failure, and that turbulence generates vibrations that travel along the pipe wall and up through whatever's above it, whether that's concrete, screed, tarmac, you name it.

George

So you're not actually hearing the water dripping, you're picking up something else entirely?

Dave

Exactly. It's not a drip sound at all. It's more of a hiss or a rumble, and the frequency changes depending on the pipe material, the water pressure, and what's covering the pipe. A copper pipe buried under concrete behaves differently to a plastic supply pipe under a tiled floor. The acoustic signal from each is distinct, and a trained engineer learns to read those differences.

George

Walk me through what actually happens on a job. You turn up, you've got your kit, where do you start?

Dave

First thing is to confirm there is a live leak on the supply. We'll check the stop tap, isolate appliances, watch the meter. Once we've established water is escaping, we map out the pipe run as best we can, using any building plans available or by tracing from known connection points. Then we place acoustic listening devices, which are essentially very sensitive ground microphones, at fixed points along that pipe run. Access points like stop taps, valve covers or exposed pipe ends are ideal because the sensor makes direct contact with the pipe or the surface directly above it.

George

And the equipment's picking up those vibrations you mentioned? What does the engineer actually see or hear through it?

Dave

The engineer listens through headphones and also watches a display showing the signal amplitude. Where the leak is loudest, the amplitude peaks. You work along the pipe run, repositioning the sensor, and you're listening for where that peak occurs. It's a bit like tuning in to the signal.

George

That makes sense for a straight run, but pipes don't always go in straight lines under a house, do they? How do you handle that?

Dave

No, they don't. Pipes bend, branch off, run diagonally. That's where a leak noise correlator becomes really valuable. A correlator connects two sensors placed at separate points along the pipe, one either side of the suspected leak zone. The device measures the tiny time difference between the leak sound arriving at each sensor and uses that delay, combined with the pipe's known sound velocity, to calculate exactly how far the leak sits from each sensor.

George

So it's essentially doing the maths for you. That's clever. Does the surface covering the pipe affect how well this works?

Dave

It does, and it's worth being honest about that. Dense concrete transmits acoustic signals well. Loose gravel or a suspended timber floor absorbs and scatters them. Tarmac on a driveway is actually pretty good. The engineer has to account for the surface when interpreting the data, because a weak signal doesn't always mean a small leak. It can mean the covering material is damping the sound.

George

And once the equipment's given you a location, what happens? Do you just start digging?

Dave

Not immediately, no. ADI's engineers typically cross-reference the acoustic finding with at least one other method before any excavation is recommended. Thermal imaging can confirm heat loss through a floor surface above a warm-water pipe leak. Tracer gas detection is another option for awkward locations where acoustic signals are unclear. The idea is to be as precise as possible so that any opening up is targeted and minimal.

George

That's a really clear picture of how the whole process fits together. Dave, thanks so much for breaking that down. If you're dealing with an unexplained rise in your water bill or a meter that won't stop moving, ADI Leak Detection are among the most respected specialists in the UK for tracking down exactly where that water's going. We'll be back with more in the next episode.

How this episode was made. This episode was produced using AI-generated voices and script, based on real leak detection questions and the working knowledge of ADI Leak Detection engineers. More about how the podcast is made.