Does home insurance cover leak detection?

Usually yes. Almost all UK buildings insurance policies include a 'trace and access' clause, which pays for the cost of finding the source of an escape of water and making good the damage caused getting to it — lifting floors, chasing walls, opening ceilings. The limit is commonly £5,000 but ranges from about £2,500 to £10,000 depending on the policy. The detection survey itself usually falls inside that cover, and many leak-detection firms (including us) can produce a report written specifically for your insurer. Check your policy's trace-and-access limit and excess before you start, and keep the survey report and invoice for the claim.

What is the difference between acoustic and thermal leak detection?

Acoustic detection uses sensitive ground microphones and pipe correlators to listen for the high-frequency hiss of pressurised water escaping from a pipe — it is the workhorse method for mains and heating leaks under floors, screed and pavements. Thermal imaging uses an infrared camera to map temperature differences across a surface: a warm patch on a cold floor reveals a hot-water or underfloor-heating leak, and a cold damp patch can reveal evaporation from a cold-water leak. The two are complementary, not rival — acoustic finds the noise, thermal finds the heat signature, and a thorough survey often uses both to confirm a pinpoint before anyone opens up the floor. Cold-water pipes that make no noise and have no heat signature are where tracer gas comes in.

How long does a leak detection survey take?

Most domestic leak surveys in a London flat or house take one to three hours on site. A straightforward pressurised-pipe leak under a kitchen or bathroom floor is often pinpointed within the hour. Larger properties, leaks under a concrete screed with underfloor heating, or jobs that need several methods (acoustic, then thermal, then tracer gas to confirm) take longer. Below-ground drainage leaks that need a CCTV camera run add time depending on the length of the run. We give you a finding on the day in the large majority of cases, plus a written report you can pass to your insurer or use to brief the repair.

Can you detect a leak under a concrete floor or underfloor heating?

Yes — and this is exactly where professional detection earns its fee, because lifting a screed floor to guess is ruinously expensive. Underfloor heating leaks are usually found with thermal imaging, which shows the warm leak as a bright signature against the cooler floor, often confirmed with acoustic listening and a pressure test on the heating circuit. Cold-water pipes buried in screed that make no noise and give no heat signature are found with tracer gas: a safe hydrogen/nitrogen mix is injected into the drained pipe and the gas, being the smallest molecule, escapes at the leak and is picked up at the floor surface with a gas detector. The point of all of it is a single pinpoint so the repair opens one tile, not the whole room.

Is leak detection worth it, or should I just get the leak repaired?

If you can see exactly where the leak is — a dripping joint under the sink, a weeping radiator valve — you don't need detection; you need a repair. Detection is worth paying for when the leak is hidden: water staining a ceiling two floors down, an unexplained drop in boiler pressure, a damp patch with no obvious source, or a water meter ticking over with everything turned off. In those cases a £150–£400 survey that pinpoints the leak is almost always cheaper than the alternative of opening up floors and walls speculatively, and it means the repair is fast and targeted. It also gives you the documented cause your insurer needs. Detection without a clear repair plan is half a job — the right firm finds it and fixes it.

How Much Does Leak Detection Cost in London? Acoustic, Thermal and Tracer Gas Prices (2026)

Q: How much does leak detection cost in London?

In 2026 a non-invasive leak detection survey in London typically costs £150–£400. A basic acoustic survey to pinpoint a pressurised water leak is £150–£300; a full multi-method survey using acoustic, thermal imaging and moisture mapping is £250–£450; an emergency or out-of-hours visit is £350–£550. Tracer gas (for silent buried or cold-water pipes) adds £80–£200, and a CCTV drain survey for waste-pipe and below-ground leaks is £150–£400. Because most home insurance includes 'trace and access' cover, the survey cost is frequently claimable on an insured escape of water — always ask for a fixed price before booking.

What leak detection costs in London in 2026 — acoustic, thermal imaging and tracer gas surveys, what each method finds, and how your insurance pays for it.

A hidden leak is one of the few household problems where the finding can cost as much as the fixing — and where getting the finding wrong is what turns a £200 repair into a £4,000 one. A stain spreads across a Clapham ceiling, the boiler pressure keeps dropping in a Camden flat, the water meter ticks over at 3am with every tap shut: the water is clearly escaping somewhere, but where? This guide sets out exactly what professional leak detection costs in London in 2026, what each method actually does, and — crucially — how your insurance usually pays for most of it.

Why Pay for Detection at All?

The temptation, when a leak is hidden, is to start opening things up: lift a few floorboards, pull a bath panel, chase out the wall where the damp is worst. In a modern London property that instinct is expensive and often wrong. Water travels — it runs along a joist, down a cavity, across a screed — so the wettest patch on your ceiling is frequently nowhere near the leak above it. Speculative opening-up means damage you then have to make good and a leak you still haven't found.

Professional leak detection exists to replace guesswork with a pinpoint. A surveyor uses non-invasive equipment to locate the leak to within a few centimetres before anyone touches the structure, so the repair opens one tile or one short section of floor rather than a whole room. On a typical job the £150–£400 survey fee is a fraction of what blind excavation would cost — and because the cause is then documented, it's also exactly what your insurer wants to see. The cheapest leak is the one found precisely the first time.

The Methods (and What Each One Finds)

There is no single magic "leak detector." A good London leak company carries several technologies and chooses by the type of leak. The five you'll meet:

Acoustic detection. The workhorse. Sensitive ground microphones and pipe correlators listen for the high-frequency hiss of pressurised water escaping. Ideal for mains supply pipes and pressurised central-heating pipes under floors, screed and pavements. A correlator placed at two points on a pipe can locate a leak between them by the tiny time difference in the sound reaching each sensor.
Thermal imaging. An infrared camera maps surface temperature. A warm signature on a cool floor exposes a hot-water or underfloor-heating leak; a cold, evaporating patch can reveal a cold-water escape. Fast, completely non-invasive, and the go-to for screed-buried heating circuits.
Tracer gas. For the silent leaks nothing else can catch — buried cold-water pipes that make no noise and carry no heat. A safe hydrogen/nitrogen mix (typically 5% hydrogen, 95% nitrogen) is injected into the drained pipe; hydrogen, the smallest molecule there is, escapes at the leak and rises to the surface where a gas detector picks it up.
Moisture mapping and damp meters. Used to confirm the spread of water and rule areas in or out, narrowing where the other methods focus.
CCTV drain cameras. For below-ground waste and drainage leaks — a self-levelling camera runs the drain to find cracks, displaced joints, root ingress or a collapse. This is also what surveys a leak that's actually a drainage fault rather than a supply one.

The skill is in the sequencing: a surveyor might start with acoustic, confirm a suspected hot-water leak with the thermal camera, and use a pressure test plus tracer gas to nail the exact point before recommending the repair. In London the housing stock makes this varied work — Victorian conversions with branched lead and iron supply pipes, 1960s blocks with leaks two floors above the damage, new-builds with cold-water pipes set in concrete screed under engineered timber floors.

2026 London Cost Guide

Indicative London pricing from our own job log this year. Every survey is quoted as a fixed price before we attend — no open-ended hourly meter.

Service	Typical London cost (2026)
Basic acoustic leak survey (single pressurised leak)	£150–£300
Full multi-method survey (acoustic + thermal + moisture)	£250–£450
Emergency / out-of-hours leak detection call-out	£350–£550
Tracer gas (buried / cold-water / silent leaks) add-on	£80–£200
Underfloor heating leak survey (thermal + pressure test)	£250–£500
CCTV drain survey (below-ground waste leak)	£150–£400
Insurance-grade report for trace-and-access claim	Often included; £50–£120 if standalone
Detect-and-fix combined visit (detection + minor repair)	From £280

A useful rule of thumb: a simple, accessible leak is at the bottom of those ranges; a leak under a screed floor, in a high-rise flat with restricted access, or one needing three methods to confirm sits at the top. The detect-and-fix figure matters because a survey that ends with "the leak is here" but no repair is only half the job — the value is in walking away with it found and stopped.

What Changes the Price

Five things move a London leak survey up or down the ranges above:

How accessible the leak is. A leak under a lifted laminate floor is quick; one under a tiled, screeded bathroom with underfloor heating needs more method and more time.
Which methods are needed. Acoustic alone is cheaper than a job that also needs thermal imaging and tracer gas to confirm a silent cold-water leak.
Time of day. An out-of-hours or weekend emergency for an active escape of water carries the call-out premium in the table.
Property type. A purpose-built block where the leak originates two floors up, or a listed Victorian conversion with awkward concealed pipework, takes longer than a modern terraced house.
Whether repair follows. Booking detection and repair together is usually better value than two separate visits and two call-out fees.

Trace and Access: How Insurance Pays

This is the part most people don't realise until after they've paid out of pocket. Almost every UK buildings insurance policy contains a "trace and access" clause. It covers the cost of finding the source of an escape of water and making good the damage caused by getting to it — the lifted floor, the chased wall, the opened ceiling — separately from repairing the leak itself. Typical limits are around £5,000, ranging from roughly £2,500 to £10,000 by policy.

In practice that means that for a genuine insured leak, the detection survey is frequently claimable rather than a sunk cost. The process is straightforward: check your policy's trace-and-access limit and your excess, get the leak detected by a firm that can write a report specifically for insurers, and submit the report and invoice with your claim. Keep everything documented — the same discipline that applies to a burst pipe claim. What trace-and-access generally won't cover is gradual damage you knew about and ignored, or wear-and-tear maintenance, so act promptly once you suspect a hidden leak.

Supply-Pipe Leaks and Thames Water

One London-specific point worth money: if the leak is on the supply pipe — the underground pipe carrying mains water from the boundary stop tap into your property — the section from the boundary to your home is legally your responsibility to maintain, not Thames Water's. But before you pay for excavation, check the support that exists. Thames Water runs schemes that will, in qualifying cases, repair a leaking customer-side supply pipe free of charge, and it deals with leaks on the company's side of the boundary and on shared supplies as a matter of course. For a confirmed external supply-pipe leak, a quick call to Thames Water before you commission private excavation can occasionally save the whole repair bill.

Internally, a hidden supply or heating leak that keeps dropping your boiler pressure or running your meter is yours to find and fix — and that's where a detection survey earns its keep. If you're not sure whether the leak is on the supply pipe, the heating circuit or a waste pipe, that's precisely the question a survey answers on the day.

Choosing a Leak Detection Company in London

A few things separate a good leak firm from an expensive guess:

They detect before they dig. Be wary of anyone who wants to start opening up the structure before trying to pinpoint the leak non-invasively. The whole point of detection is to avoid speculative damage.
They carry more than one method. A van with only a damp meter isn't leak detection. Acoustic, thermal and tracer gas between them cover the great majority of London leaks.
They quote a fixed survey price. You should know the cost before they arrive, not discover it on an open-ended hourly basis afterwards.
They can write for your insurer. A clear report with the cause, location and method documented is what gets a trace-and-access claim paid.
They can fix what they find. Detection and repair under one roof means no second call-out fee and no handing you a location with no solution.

Our own leak detection team covers all 32 boroughs with acoustic, thermal-imaging and tracer-gas equipment, attends emergencies 24/7, and provides an insurer-ready report as standard — and because we're an emergency plumbing firm first, we repair what we find on the same visit wherever the pipe is accessible.

The Bottom Line

Budget £150–£400 for a non-invasive leak survey in London in 2026, more for an out-of-hours emergency or a screed-buried underfloor-heating leak — but before you treat that as a cost, check your buildings insurance for trace-and-access cover, because it very often pays. Use a firm that detects with the right method rather than the only one they own, that quotes a fixed price, and that can both find the leak and fix it. The survey that pinpoints a hidden leak to a single tile is one of the best-value calls you can make, because the bill it prevents — a floor lifted on a guess, a ceiling down two flats below — is always the bigger one.