Listen. Locate. Repair.

Acoustic Leak Detection

Every pressurised leak makes a sound. Water forcing its way through a split or pinhole produces a distinct hiss and vibration that travels along the pipe and through the surrounding structure. Acoustic leak detection is the craft of hearing that sound, filtering out everything else, and following it to its loudest point — the leak itself.

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Quick answer

Acoustic leak detection uses sensitive microphones and ground sensors to hear water escaping from a pressurised pipe, so the leak can be pinpointed without digging. Typical UK trade cost-guide ranges put a survey at roughly 150 to 400 pounds, depending on access, pipe type and how long the trace takes.

Acoustic leak detection costs in London

Job	Typical cost	Time
Acoustic survey on exposed metal pipework	150 to 300 pounds	1 to 2 hours
Ground microphone and correlator trace on buried mains	250 to 450 pounds	2 to 3 hours
Acoustic trace with cross-confirmation on plastic pipe	300 to 500 pounds	2 to 4 hours
Callout and first hour on site	80 to 150 pounds	First hour
Written report for an insurance claim	60 to 150 pounds	Same or next day

Typical UK trade cost-guide ranges, not a quote. Our detection fee is fixed and agreed at booking.

Our engineers use ground microphones, listening sticks and electronic correlators to survey floors, walls and external ground. On buried mains, a correlator compares how fast the leak noise reaches two sensors and calculates the position between them to within a fraction of a metre.

Acoustic methods shine where leaks hide deepest: under solid concrete floors, beneath driveways, and along long supply pipe runs where digging speculatively would cost thousands.

Included within our standard leak detection visit — no find, no fee applies.

What you get

Ground microphones and listening sticks for floors and external ground
Leak noise correlators for buried and long-run pipework
Works through concrete, screed, tile and paving
Ideal for mains and pressurised heating circuits
Combined with pressure testing to confirm before we survey
Precise marking so any excavation is a single small hole

How it works

A method, not a guess

Confirm the leak is live

Meter and pressure checks prove water is escaping and from which circuit.

Quiet the system

We isolate outlets so the only sound on the pipe is the leak itself.

Survey and correlate

Microphones map the noise; the loudest, lowest-frequency point marks the escape.

Mark and verify

The location is marked physically, cross-checked with a second method where possible.

Before you book anyone

6 things to know before you book acoustic leak detection in London

Acoustic alone often fails on plastic pipe - insist on a multi-method survey

Acoustic detection is superb on copper and steel, pinpointing leaks to within centimetres with a 90-95% success rate on metal pipe in concrete. On plastic pipe - standard in most London homes built or replumbed since the 1990s - the leak noise dissipates into the pipe wall and surrounding ground instead of travelling along the water column. A firm that turns up with only a listening stick can genuinely miss a plastic-pipe leak. Ask what happens when acoustic draws a blank: tracer gas, thermal imaging and moisture mapping should be on the van, not a second chargeable visit away.

Hourly rates are the most expensive way to buy detection

London plumbers advertising £63-£105 per hour sound cheaper than a £400 survey, but leak detection is open-ended work: a tricky trace can absorb four to six hours, and one Trustpilot reviewer described six hours billed with no leak found. Emergency rates run £140-£200 per hour plus evening surcharges of £50-£120. UK detection-only fixed fees typically sit at £395-£600 plus VAT, so a fixed price agreed before anyone arrives usually beats an hourly meter that only stops when the engineer gives up. Ask for the total figure in writing at booking.

Read the small print on "no find, no fee"

Many firms advertise no find no fee, then exclude the leaks Londoners most commonly have. A frequent carve-out limits the guarantee to internal hot and cold supply pipes only - so a central heating leak, the classic cause of a combi boiler losing pressure, is billed in full whether found or not. Others reserve the right to charge for "time on site" or a report even when nothing is located. Before booking, ask one direct question: "If you do not physically locate my leak, what exactly do I pay?" Get the answer in writing.

The 20-minute damp-meter visit is a known scam pattern

A recurring complaint on UK consumer forums: a company promises acoustic and infrared equipment on the phone, then sends someone who waves a £30 damp meter around for twenty minutes and invoices £150. A moisture meter shows where water has ended up, not where it escapes - which is the entire point of paying a specialist. On arrival, ask to see the ground microphone, correlator, thermal camera and tracer gas rig before work starts. A genuine detection survey on a London house typically takes two to four hours, not twenty minutes.

Notify your insurer before you instruct anyone

Most UK buildings policies include trace and access cover - typically £5,000, with some premium tiers up to £15,000 - which pays for finding the leak and opening up to reach it. But insurers can reject costs incurred before you notified them, and loss adjusters routinely refuse vague one-line invoices. A claimable report needs the cause and origin of the leak, the detection methods used, a moisture map and photographs. Ask any firm to show you a sample report before booking; if it would not survive a loss adjuster's desk, you may end up funding the survey yourself.

Detection, access and reinstatement are three separate bills - budget for all three

The survey fee only covers finding the leak. Opening up - lifting floors, breaking tiles, cutting plasterboard - can run from a few hundred pounds to several thousand, and reinstatement is often the most expensive line of all. Homeowners describe being blindsided: a £450 detection visit followed by separate quotes for access, repair and retiling. Reputable firms are upfront about this. We charge a fixed detection fee (typically £250-£450 for a London home) and quote any repair separately before work starts, so you approve each stage rather than discovering it on an invoice.

Compare like for like

Acoustic Leak Detection In London Done Properly

Acoustic detection listens for the sound a pressurised leak makes underground or behind a wall. Used well, it pinpoints the leak before anyone lifts a floor. Used lazily, it misses plastic pipe and guesses. Here is how our approach compares with the two things most Londoners actually get quoted.

What to check	A cheap hourly quote	A one-method firm	London Leak Specialist
Kit on the van	Often a damp meter and a torch. No ground microphone, no acoustic correlator, so any pinpointing is really educated guesswork.	A ground mic or correlator only. Good on the pipes it suits, but nothing to fall back on when the sound does not carry.	Ground microphone and correlator carried as standard, plus tracer gas and thermal imaging when acoustics alone will not confirm the spot.
Metal pipe performance	May stumble onto a loud leak, but without a correlator the location is approximate and the floor still gets opened on a hunch.	Genuinely strong here. Metal carries leak noise well, so a competent acoustic operator locates it accurately.	We lead with acoustics on metal because it works, and correlate two mic points so the dig sits directly over the leak.
Plastic pipe performance	Poor. Plastic deadens leak noise, so a listen-only visit frequently ends with a shrug or a wrong guess.	This is the weak spot. Plastic muffles the sound acoustics rely on, and a single-method firm has nothing to cross-check with.	When plastic mutes the acoustic signal we cross-confirm with tracer gas or thermal imaging, so a quiet leak is still found.
How the job is priced	An hourly rate that looks cheap, then climbs as the visit drags. You pay for time on site, not for a located leak.	Usually a fixed call-out for one method. Fair if it works, but a second visit and a second charge if it does not.	A clear fixed price for the detection visit, quoted upfront. Typical UK trade cost-guide ranges, with no surprise add-ons.
No-find, no-fee	Rarely offered. The clock has run either way, so there is little incentive to actually confirm the source.	Sometimes, but often voided the moment their one method cannot detect the leak, which is exactly when you need cover.	If we genuinely cannot locate your leak using our full range of methods, you do not pay the detection fee. Agreed before we start.
The damp-meter-only pattern	A meter reads damp, they declare a leak, and you fund exploratory digging. Damp confirms a symptom, not a location.	Less likely, though a stalled acoustic visit can still end in guesswork if there is no backup method to confirm.	A damp reading only starts the job. We do not dig until acoustics or a backup method pinpoints the actual source.
Report for your insurer	Usually just an invoice. No findings, no images, nothing an insurer will accept for a trace-and-access claim.	A basic note may be provided, but often lacks the imaging or method detail a claims handler asks to see.	A written report with findings, location and supporting images, prepared so it stands up for a trace-and-access claim.

From the forums

What Londoners say on Reddit & forums

London homeowners compare notes on leak detection constantly - on Reddit, MoneySavingExpert and trade forums - and the same frustrations come up again and again: surveys that found nothing but still cost money, guarantees that evaporated in the small print, and confusion over who actually pays. Here is what the community consensus looks like.

On MoneySavingExpert, homeowners disputing detection bills

A widely-discussed thread involved a homeowner charged £150 for a visit lasting roughly twenty minutes, where the engineer used only a basic damp meter despite acoustic and infrared equipment being promised on the phone. Forum users were blunt: the service delivered did not match what was sold, and several doubted the invoice would survive a court claim. Our take: the equipment promised at booking should be the equipment on your doorstep - ask to see it before the survey starts, and get the scope in writing.

On Trustpilot and consumer forums, "no find no fee" disappointments

Reviewers describe hours of on-site work ending with no leak located and a substantial bill regardless, because the guarantee only applied to internal hot and cold supply pipes - excluding the central heating circuits behind most London leaks. The community's advice is to interrogate the exclusions before booking, not after. Our take: a no-find-no-fee promise is only worth the circuits it covers, which is why ours applies to the leak you actually booked us to find.

On Screwfix Community and trade forums, acoustic kit on plastic pipe

Tradespeople are candid that listening equipment which performs brilliantly on copper struggles badly on plastic: the leak noise soaks into the pipe wall and ground rather than carrying along the pipe, and slow drips, low pressure and traffic noise make it worse. DIYers who bought cheap listening devices report frustration on modern plumbing. Our take: this is exactly why acoustic should be one tool among several - tracer gas and thermal imaging pick up what plastic pipework hides from microphones.

On plumbing forums, boilers losing pressure and wasted call-outs

A regular story: homeowner books leak detection for a combi boiler dropping to zero bar, only to learn the culprit was inside the boiler itself - a pressure relief valve or heat exchanger - not the pipework under the floor. Forum regulars advise ruling out the boiler's internal components before paying for a floor-by-floor trace. Our take: a competent surveyor pressure tests each circuit separately first, precisely so you do not pay to search a floor slab when the fault sits in the airing cupboard.

On r/HousingUK-style insurance threads, trace and access claims

Homeowners frequently discover their trace and access cover too late or use it wrong: limits vary hugely by insurer (commonly £5,000, with some policies paying nothing unless a premium tier was chosen), and claims stumble when work was commissioned before the insurer was notified or the report lacked evidence of cause and origin. Our take: ring your insurer first, then instruct a firm whose reports are structured for loss adjusters - it is the difference between reimbursement and a rejected claim.

On UK forums, metered water bills and underground supply pipes

People hit with sudden £800+ water bills learn the hard way that everything through the meter is theirs to pay - including water lost through a leak on their own underground supply pipe. Thames Water's code of practice expects confirmed leaks fixed within four weeks, and forum advice is to move fast: some suppliers offer a one-off leak allowance, but only once the leak is proven and repaired. Our take: an external supply pipe trace pays for itself quickly when the meter is running day and night.

Questions

Asked before every booking

How accurate is acoustic leak detection?

On a pressurised pipe with reasonable access, typically within 30 centimetres — and often better with a correlator on buried mains. Accuracy depends on pipe material, depth and background noise, which is why we cross-check with thermal or tracer gas before anyone digs.

Does it work on plastic pipes?

Yes, though plastic transmits sound less readily than metal, so we compensate with more sensitive ground microphones, closer sensor spacing and, where needed, tracer gas as the confirming method.

Can you find leaks under concrete floors?

This is exactly where acoustic detection earns its keep. The sound of a leak travels through screed and slab; we survey the floor surface in a grid and follow the signal to its peak, then confirm before any breaking out.

Is any damage caused during the survey?

None. Listening equipment sits on the surface. The point of acoustic detection is that the only opening made is the one needed for the repair itself.

How much does acoustic leak detection cost in London?

A fixed-fee domestic detection survey in London typically costs £250-£450, agreed before the visit. Nationally, detection-only fees commonly run £395-£600 plus VAT, and hourly-rate alternatives (£63-£105 per hour, £140-£200 for emergencies) frequently total more because tracing is open-ended work. The fee covers locating the leak and a written report; opening up floors or walls and the repair itself are always quoted separately.

How long does a leak detection survey take?

A thorough survey of a typical London house takes two to four hours. The engineer pressure tests each pipe circuit to isolate the leaking one, then combines acoustic listening, thermal imaging, moisture mapping and - where needed - tracer gas to pinpoint the location. Be wary of visits lasting twenty minutes with a damp meter only: that is a moisture check, not leak detection, and it is a recurring complaint on UK consumer forums.

Does acoustic leak detection work on plastic pipes?

Poorly on its own. Acoustic methods locate leaks on copper and steel with roughly 90-95% accuracy because metal carries leak noise along the pipe. Plastic pipe absorbs that noise into the pipe wall and surrounding ground, so slow leaks in modern plastic plumbing can be inaudible to ground microphones and correlators. For plastic systems, tracer gas (hydrogen/nitrogen mix) and thermal imaging are the reliable back-up methods - which is why a multi-method survey matters.

Is leak detection covered by home insurance?

Usually, through trace and access cover in your buildings policy - commonly capped at £5,000, sometimes £15,000 on premium tiers, and absent entirely from some basic policies. It pays for locating the leak and opening up to reach it, not the pipe repair itself. Notify your insurer before instructing anyone, and use a firm that produces a report with cause, origin, methods, moisture map and photos - loss adjusters reject vague invoices.

Is a hidden water leak an emergency?

Treat it as urgent even without visible flooding. A hidden leak saturates joists, screed and plaster long before a ceiling stains, and on a metered supply you pay for every lost litre - forum users report bills jumping by hundreds of pounds. Isolate the water at the stopcock if pressure loss or damp is spreading, then book detection promptly. Thames Water expects confirmed supply pipe leaks to be fixed within four weeks.

What is the difference between a listening stick and a leak correlator?

A listening stick is a simple acoustic rod pressed against fittings - cheap, but dependent on the engineer's ear and easily defeated by background noise. A correlator places two sensors on the pipe at different points and calculates the leak position from the time difference in the noise reaching each sensor, giving far greater precision on longer runs and buried pipe. Professional surveys use correlators and ground microphones together, then confirm with a second method before anyone opens a floor.

Water going somewhere it shouldn’t?

Tell us the symptoms and your postcode. We’ll confirm the visit, the fixed detection fee and the arrival window before you commit to anything.

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