Acoustic Leak Detection
Expert Acoustic leak detection services in Cornwall & Devon.
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Acoustic leak detection in Cornwall & Devon
A hidden leak is not silent. We use ground microphones and leak correlators to follow the sound of escaping water to its source, with no digging and no guesswork.
📞 Call now: 07822 025 911Acoustic leak detection finds hidden leaks by listening for the noise pressurised water makes as it escapes a pipe. DCI Leak Detection uses ground microphones and leak noise correlators to pinpoint that sound across Cornwall and Devon, with fixed pricing, insurance approved reports and No Find, No Fee on residential work (subject to terms).
Water escaping from a pressurised pipe makes a constant, distinctive noise. As it forces its way out through a crack or failed joint, it creates turbulence at the leak point, and that vibration travels along the pipe wall and up through the surrounding ground. The principle is so reliable that the leading detection equipment makers, including Sewerin, HWM and Gutermann, build whole product ranges around it, and the UK water companies use the same approach to survey their own mains.
Acoustic leak detection is the craft of capturing that sound at the surface and following it to its loudest point, which sits directly above the leak. After more than 30 years listening to pipes across Cornwall and Devon, we can usually tell a genuine leak from a humming pump or a passing tractor within seconds. You get a fixed price agreed up front, no call-out fees, and No Find, No Fee on residential leak detection (subject to terms).
🔊 How listening for leaks actually works
Think of a buried pipe as a long sound conductor. When water escapes under pressure, the leak generates a continuous rushing or hissing noise. Part of that energy travels along the pipe itself, often a surprising distance in metal pipework, and part of it radiates out through the soil or concrete above the leak.
That gives us two ways to catch it. We can listen on the pipe, using sensors clamped to accessible fittings such as stop taps, valves and hydrants. Or we can listen at the surface, sweeping a sensitive ground microphone across the floor, path or lawn above the suspected run. Either way, the rule is the same: the closer the sensor gets to the leak, the louder and clearer the noise becomes.
One practical point worth knowing: the noise only exists while the pipe is under pressure. So please leave your water switched on before an acoustic survey. A drained or isolated pipe gives the equipment nothing to hear.
🎧 Ground microphones and leak correlators: what each one does
Acoustic detection is really two complementary tools, and we carry both to every job because they solve different halves of the problem.
Ground microphones
A ground microphone is a highly sensitive sensor placed directly on the surface, connected to an amplifier, headphones and a visual display. It boosts the faint leak noise coming up through the ground and filters out as much background sound as possible. We work it in a grid pattern along the pipe route, comparing readings as we go. The position with the strongest, most consistent signal marks the leak, and that is the spot we paint on the ground for the repair.
Leak noise correlators
A correlator takes a different approach. Two sensors are attached to accessible fittings on the same pipe, one either side of the suspected leak. The leak noise travels along the pipe and reaches each sensor at a slightly different moment. The processor measures that time difference and, using the pipe material, diameter and the distance between the sensors, calculates how far along the run the leak sits. Sewerin, HWM and Gutermann all document the method in their correlator ranges, and it is the standard way water companies locate leaks on long buried mains.
| Tool | What it does | Where it shines |
|---|---|---|
| Ground microphone | Amplifies leak noise heard at the surface and filters background sound | Pinpointing the exact dig spot once the search is narrowed |
| Leak noise correlator | Calculates leak position from the time difference between two pipe-mounted sensors | Long buried runs between two access points, such as supply pipes and mains |
| Listening stick | Direct contact listening on fittings and exposed pipework | Quick checks at stop taps, valves and meters to confirm a live leak |
Used together, the correlator narrows a long pipe run down to a short stretch, and the ground microphone then pins the exact spot. The result is one small, precise excavation instead of a trench dug on a hunch.
💪 Where acoustic leak detection excels
Acoustic methods are at their best on pressurised water pipes, which covers most of the leaks we are called to:
- Mains and supply pipe leaks. The pipe between the water main and your house is usually a long, buried, pressurised run, exactly what correlation was designed for. See our mains water leak detection service.
- Underground leaks beneath gardens, drives and paths. Ground microphones pick up leak noise through soil, tarmac and paving, so nothing gets dug up until we know where to dig. Our underground water leak detection page covers this in detail.
- Pipes buried in concrete floors. Metal pipework in a solid floor carries leak noise well, so we can often locate a leak under a screed without lifting a single tile.
- Narrowing down internal leaks. Before anyone opens a wall or floor, acoustic listening tells us which section of pipework is actually making the noise.
If the leak sits on the stretch between the meter and your house, it pays to find it quickly: Ofwat and South West Water both confirm that this supply pipe is normally the property owner’s responsibility, not the water company’s. Our guide on how to find a water leak underground covers the checks you can make yourself before calling anyone, and our main water leak detection page explains how acoustic work fits into a full survey.
⚖️ The honest limits of acoustic detection
Any leak detection company that tells you one method finds every leak is selling, not surveying. Acoustic detection has known limits, and being upfront about them is how we choose the right tool for your job:
Plastic pipe carries less sound than metal. Research published by the US Environmental Protection Agency and the equipment manufacturers’ own technical guidance agree on this: PVC and MDPE pipes transmit leak noise less efficiently than metal, so the sound fades over a shorter distance and at a lower pitch. Plastic runs are still detectable, but they need sensors placed closer together, more patience, and sometimes a different method altogether.
Quiet conditions matter. Leak noise is faint by the time it reaches the surface. Traffic, machinery, pumps and even strong wind can drown it out, which is why water companies have traditionally surveyed their mains overnight. We plan timing and equipment settings around the site, because a quiet rural garden listens very differently to a main road in town.
Pressure makes the noise. Less pressure means less sound. A low pressure system or a pipe that has already been drained gives acoustic equipment very little to work with, and that is precisely when we reach for tracer gas instead.
🧪 When we combine acoustic with tracer gas and thermal imaging
On the jobs where acoustics face their limits, we bring in the other half of the kit:
Tracer gas takes over where sound runs out. We drain the pipe and charge it with the industry standard tracer gas, a mix of 5 per cent hydrogen in 95 per cent nitrogen that is non flammable and safe in use. The gas escapes through the leak and rises through soil, screed or concrete, where a sensitive detector picks it up at the surface. It is the natural partner for plastic pipework and low pressure systems. Our tracer gas leak detection page explains the method in full.
Thermal imaging works on temperature rather than sound. Our FLIR cameras show the warm or cool patterns that escaping water creates on a surface, which makes them ideal for heating leaks and for confirming what the acoustic readings suggest before anything is opened up. See how thermal imaging leak detection works in practice.
Most surveys use more than one method. Acoustic listening narrows the search, then a second technique confirms it, so the mark on the floor is one we would stake the No Find, No Fee promise on. Because we would, and we do.
📋 What an acoustic leak detection visit looks like
Talk it through
You describe the symptoms over the phone: the bill, the damp patch, the sound of running water. We agree a fixed price for the survey before we set off. No call-out fee.
Map the pipework
On site, we trace the pipe route and note materials, joints and access points. Metal and plastic call for different settings, so knowing what we are listening to comes first.
Confirm a live leak
Meter checks and pressure testing confirm the leak is real and which circuit it sits on, so we are not chasing a noise that turns out to be normal flow.
Correlate the run
On longer buried runs, correlator sensors go on the fittings either side of the suspect section and the equipment calculates where along the pipe the leak sits.
Pinpoint with the ground microphone
We sweep the surface above the narrowed section, comparing readings until the loudest, most consistent signal marks the spot, then confirm with a second method where needed.
Mark, photograph, report
The leak position is marked and photographed, and the findings written up. If you are claiming, the report is built for your insurer’s trace and access process.
✅ Ready to put a trained ear on your pipes?
Every day a leak runs, it wastes water and feeds the damage. One acoustic survey pinpoints it, with the evidence your insurer needs.
Call Dickie on 07822 025 911
No Find, No Fee on residential leak detection (subject to terms). No call-out fees, fixed prices, and a local team covering the whole of Cornwall and Devon. You can also email hello@dcileakdetection.co.uk or use the quote form above.
📞 07822 025 911📍 Find us in Cornwall & Devon
🔊 Acoustic leak detection across Cornwall & Devon
Frequently Asked Questions About Acoustic Leak Detection
What exactly is acoustic leak detection and how does it work?
Think of it as a stethoscope for your pipes. When water escapes under pressure, it creates specific sounds – typically a hollow “whoosh” or hiss at 500-1500Hz for metal pipes. My ground microphones amplify these sounds up to 100 times, filtering out background noise to isolate the leak signature. The equipment converts vibrations into electrical signals, displaying both audio and visual readings. Where the sound’s loudest, that’s your leak – usually accurate to within 30cm. After four decades listening to pipes, I can tell the difference between a pinhole leak and a split joint just from the tone.
Can acoustic detection work on plastic pipes?
Yes, but it is trickier. Plastic pipes such as PVC and MDPE transmit sound far less well than metal, so leak noise is quieter and does not travel as far along the pipe. The softer material absorbs the sound energy. We adjust our equipment’s frequency filters for plastic and often combine acoustics with tracer gas on these jobs, which keeps results reliable. It simply takes more patience and experience.
What size leaks can acoustic equipment detect?
I’ve found leaks as small as 2mm – that’s smaller than a match head. The key isn’t size, it’s pressure. At 30+ psi (typical UK mains), even tiny leaks create detectable noise. Pinhole leaks in metal pipes actually produce higher frequencies that carry well. The smallest leak I ever found was a hairline crack in copper pipe, losing just 10 litres a day. Larger leaks are obviously easier – anything over 5mm sounds like a kettle boiling underground. But remember, small leaks grow into big problems, so finding them early saves thousands.
Does acoustic leak detection work through concrete floors?
Absolutely, and it is one of our most common jobs. Sound waves travel well through concrete, especially from metal pipes, because the solid slab transmits vibration efficiently. We place sensors directly on the floor surface and the acoustic signal passes through. Thicker slabs need more amplification, but they rarely stop a survey. It is far better than breaking up your floor on a guess.
Acoustic correlation is one of several methods used to detect leaks in mains water supply lines.
When doesn't acoustic detection work well?
Low pressure systems are harder because less pressure means less noise. Several pipes running close together can confuse readings, very wet ground dampens sound and shortens range, and busy environments next to roads or machinery need careful filtering. Pooled water around a leak acts like acoustic insulation too. That is why we carry backup methods: when acoustics struggle, we switch to tracer gas or thermal imaging to get the job done.
How long does acoustic leak detection take?
For a typical three-bedroom house, allow a few hours. We start by mapping your pipe routes, then listen systematically at key points: every valve, every accessible joint. A small bungalow is quicker, while a large commercial property can take a full day. Once we have found the general area, the final pinpointing is usually the quick part. We do not rush, because accuracy matters more than speed.
Is acoustic leak detection accurate enough to avoid damaging my property?
Accurate acoustic detection means one small, targeted excavation rather than digging up entire rooms in the hope of finding the pipe. We mark the exact spot, photograph it and record the findings in your report, so whoever carries out the repair knows precisely where to open up. Modern digital equipment helps, but interpreting the sounds correctly, telling water hammer from a genuine leak, takes years of experience.
Do I need to turn off my water for acoustic testing?
No – in fact, I need your water on and pressurised. Acoustic detection relies on water actively escaping under pressure to create sound. Higher pressure actually helps – makes leaks louder and easier to find. I might ask you to turn off washing machines or other noisy appliances temporarily, but your water stays on throughout. Only exception is if you’ve got a massive leak flooding the property – then we shut off and use tracer gas instead. But for most hidden leaks, water on is essential.
Can you detect underground leaks with acoustic equipment?
Yes, that’s one of acoustic detection’s strengths. I use specialist ground microphones designed for soil contact. In rocky Cornwall ground, sound travels brilliantly – I’ve traced leaks 50 metres from source. Devon’s clay is trickier but still manageable. Depth matters less than you’d think – detected leaks 2 metres deep using the right frequency filters. The microphones pick up vibrations travelling through soil and pipe walls. For mains water leaks under driveways, acoustic detection saves thousands in excavation costs.
What's the difference between acoustic detection and listening sticks?
Traditional listening sticks rely entirely on human hearing, with no amplification, no filtering and a limited frequency range. They can catch an obvious large leak but miss anything subtle. Modern electronic acoustic equipment amplifies the sound many times over, displays frequencies visually, filters out background noise and records the measurements. The result is that modern acoustic leak detectors find quiet leaks the old methods miss completely.
How do I know if I need acoustic leak detection?
An unexplained rise in your water bill is the classic sign. Watch too for low or gradually worsening water pressure, damp patches that never dry out, a hollow sound under floors, the noise of running water when everything is off, and a boiler that keeps losing pressure. If your meter moves with all taps closed, you definitely have a leak. Small leaks become big problems, so do not wait.
Is acoustic leak detection safe for my home?
Completely safe and non-invasive. No drilling, no chemicals, no radiation – just sensitive microphones listening to your pipes. The equipment runs on batteries, no mains connection needed. Won’t damage decorations, flooring, or landscaping. Safe around children and pets. Compare that to traditional detection methods: ripping up floors, breaking walls, digging gardens. Acoustic detection preserves your property while finding leaks.