Leak Detection for Loss Adjusters: What You Get and What It Proves

A loss adjuster instructing leak detection is not buying a repair. You are buying a fact: where the water came from, roughly when it started, and whether the policy responds. Everything else is overhead.

Association of British Insurers figures for 2025, reported by Reinsurance News, put UK property payouts at a record £6.1 billion across more than 560,000 home insurance claims, with the average home claim rising by almost £800 to around £6,000. Escape of water is a large share of that volume, and most of it turns on one question a plumber's invoice cannot answer: what was the predominant cause.

Across our last 400 leak detection surveys, the cause was found in 95% of cases. In 2% the water was coming from a neighbouring property. In 3% it was not a plumbing leak at all: gutters, roofs and other structural defects letting water in. Those last two numbers matter more to a claims file than the first one, because they are the findings that change a claim rather than confirm it.

What the instruction buys

We attend across London out to the M25, all 32 boroughs. The engineers are qualified plumbers working to a detection brief, not surveyors with a moisture meter and not repair crews looking for a follow-on job.

Detection is charged at a fixed hourly rate, agreed before anyone travels and not increased on the day. Standard leak detection is £160 an hour. Trace and access, heating and mains work is £200 an hour. Moisture mapping starts at £175 an hour and emergency attendance starts at £220 an hour. Most domestic visits take two to four hours, so a standard survey lands between £320 and £640. On trace and access instructions, report writing is inside the hours worked rather than billed on top. The full schedule is on our pricing page.

Behind the rate sits no find, no fee. If we attend a confirmed live leak and cannot locate it, the detection time is not charged. That is deliberately narrow and we say so: it applies to a leak that is actually running, not to a wet patch that has stopped.

For scale, the buildings policy in one published ombudsman decision carried up to £5,000 for "locating the source of the damage including the reinstatement of any wall, flooring or ceiling removed or damaged during the search". Detection sits at the small end of that limit. Reinstatement is what consumes it.

Turnaround, and what actually delays it

The written report is normally with you within 48 hours of the visit. Same-day and next-day attendance is routine in central and inner London; outer boroughs and the far side of the M25 depend on the day.

What causes real delay is rarely our diary. It is access. A leak manifesting in a ground-floor ceiling is very often not a ground-floor leak, and a survey that cannot get into the flat above returns a partial answer. Flag it on instruction if the system has already been isolated, because a leak that is not running cannot be heard acoustically. In those cases we say what we could and could not exclude rather than manufacture a conclusion.

How cause and origin are established

The sequence is non-destructive first, invasive last. That order is not politeness, it is evidential: once a floor is up, the pre-existing condition of what was underneath is a matter of photographs.

1. System isolation and pressure testing. Isolate sections in turn and watch the pressure. This is what separates a supply-side leak from a heating leak from a waste leak, and it is the only step that produces a binary answer.
2. Thermal imaging. Useful on hot-water and heating circuits and on underfloor systems, where a warm plume shows the flow path. On cold-water leaks it shows evaporative cooling, which is a weaker signal and is reported as such.
3. Acoustic detection. Correlation and ground microphone work on pressurised pipes. Needs the leak to be live.
4. Moisture profiling. Mapping the wet area to find the gradient. Water tracks; the highest reading is not always above the leak, but the shape of the field usually points back to it.
5. Tracer gas. A mixture of 5% hydrogen in 95% nitrogen, which is non-flammable at that concentration and uses the smallest gas molecule available to escape through a small defect and rise to the surface. Reserved for buried, screeded or otherwise unreachable pipework.
6. Targeted opening up. Only once a location has been narrowed, and photographed before and after.

Two distinctions carry weight in a report. The first is between direct and indirect moisture measurement, the second between invasive and non-invasive technique. Both are named competencies in the RICS, Historic England and Property Care Association joint position statement on investigating moisture in buildings, which also lists the instruments: electrical resistance meters, capacitance meters, microwave meters, gravimetric analysis, thermal imaging, hygrometers and data loggers. A capacitance reading is not a moisture content. If a report quotes a number, it should say which instrument produced it. Our detection methods page sets out which we use and when.

Exclusion testing matters as much as location. Flood-testing a shower enclosure, a tray or a seal is how a sealant-failure argument becomes evidence rather than assertion. Where the question is "leak or damp", a dedicated moisture mapping survey is the better instruction, because the answer is a pattern over time rather than a point on a pipe.

What is in the report

Every report names a cause, or states plainly that the cause could not be established and lists what was excluded and by which method. There is no third option and no field left blank.

• Instruction details: who instructed, claim reference, date and time on site, who was present.
• The cause, stated as an opinion with the evidence that supports it.
• The location, marked on a plan or a photograph, not described in prose alone.
• Method used at each stage, and what each method ruled out.
• Moisture readings with the instrument named, taken at referenced positions rather than as a single headline figure.
• Photographs indexed to the readings and the location, so a reader can see what the text asserts.
• Extent of affected fabric, which is routinely wider than the visible staining.
• An opinion on whether the damage is consistent with a sudden escape or with a long-running condition, and whether it would have been visible to an occupier.
• Scope and limitations: what could not be inspected and why.

That last pair of items is where most detection reports fail, and it is not a stylistic complaint. In one published Financial Ombudsman Service decision, an insurer's surveyor report had the cause-of-damage field empty because, as the insurer explained, "our supplier's system doesn't always fill in this information on the report". The ombudsman's response was direct: "It's disappointing that a professional report omits this key opinion as to the cause of damage." The ombudsman went to the surveyor's on-site voice dictation instead, and the decline was ultimately overturned.

The report has to survive an ombudsman, not just satisfy the file

The evidential structure of an escape of water dispute is settled in published decisions, and it shapes what a report must contain. The policyholder must demonstrate an insured loss. Once they have, the insurer carries the onus of showing that an exclusion applies. That asymmetry is the reason a vague finding hurts the insurer more than the policyholder. A report that says "long-term damage" and nothing else does not discharge the onus on a gradual damage exclusion.

On gradual operating causes specifically, the ombudsman's approach, as one insurer summarised it in its own final response, is that the insurer "must also show that the policy holder would have been reasonably aware of the damage occurring". In that case the leak was under floor tiling, the damage was largely hidden, and the exclusion failed on that point alone. So the question a detection report must answer is not only how long the leak had been running, but whether there was anything an occupier could have seen. Those are different findings and they need separate sentences. We cover the mechanics of ageing a leak in more detail in how to tell if a water leak is new or old.

The operative test is predominant cause, not contributing cause. In a decision issued in November 2025, failed shower sealant was accepted as a peripheral factor while a corroded shower valve hidden behind tiles was held to be the predominant cause, and the complaint was upheld against the insurer. Two things carried it. First the photographs: the ombudsman examined the images relied on for the sealant argument and found that signs of deterioration and gaps "aren't obvious", while the policyholder's own photographs "clearly show the valve bracket behind the tiles to be heavily corroded". Then visibility: corrosion would ordinarily be excluded, but the decision recorded that the service "doesn't expect the customer to deal with corrosion or wear or tear which isn't visible or couldn't have reasonably been known about". Photographs that do not show what the surrounding text asserts are worse than no photographs at all.

There is also a deadlock worth knowing about. In a 2022 decision the ombudsman acknowledged it "may seem circular" for an insurer to require proof of where a leak is coming from before authorising the trace and access cover that would find it. The complaint failed only because other causes had not yet been ruled out; the decision added that once all professional advice has been followed and the source is still unidentified, it would be reasonable to expect the cover to engage. Instructing detection early is the cheapest way out of that loop, and it sits comfortably with ICOBS 8.1.1R, which requires an insurer to handle claims promptly and fairly and not to reject a claim unreasonably.

When the finding is unhelpful to the claim

We write it as we found it. The conclusion does not move because of who instructed us, and a firm that would adjust it for you would adjust it for the other side later. In practice the unhelpful findings fall into three groups.

Not a plumbing leak. In 3% of our last 400 surveys the water was entering through gutters, roofs or other structural defects. That finding may end an escape of water claim, but it closes the file with something defensible attached to it, and it redirects the policyholder to the right remedy instead of leaving them to re-report the same loss in six months.

A neighbouring property. In 2% the source was next door or upstairs. This is where a precise report earns its fee twice, because there is no strict liability for a leak between flats. Recovery normally requires negligence or nuisance, which turns on whether the neighbour knew or ought to have known of the problem and failed to act. That makes "when did it start and was it visible" the decisive fact for subrogation, not just for the indemnity. We set the position out for occupiers in who pays when a leak damages a neighbour's flat.

A cause that engages an exclusion. Wear, corrosion, failed sealant, a maintenance defect. We report it, with the evidence, and with an explicit view on visibility. That last part is what makes the finding usable rather than merely awkward, given where the onus sits.

And in the 5% where the cause was not established, no find, no fee applies to the detection time on a confirmed live leak. The report still goes out, setting out what was excluded, so the file is not simply back where it started. That mechanism is explained in full in no find, no fee leak detection explained.

How to instruct

Call 020 7123 8560 or email the instruction. We confirm the rate and the attendance window before anyone travels, and that rate does not change on the day.

What we need at instruction, in order of how often it is missing:

• Site address, and the access contact with a mobile number.
• Whether the flat or property above can be accessed on the same visit.
• Policyholder name and claim reference for the report header.
• What has been observed, and the date it was first noticed.
• Whether the water is currently running or the system has been isolated.
• Whether anything has already been opened up, dried or repaired.
• The trace and access limit and whether it is authorised, and who is being invoiced: you or the policyholder.

Invoicing is whichever you specify at instruction. Repairs are quoted separately after the cause is found, so the detection finding is not tied to a repair we are trying to sell. Where drying or reinstatement follows, we coordinate with the contractors handling it.

Background on how the cover works sits on our trace and access page and our escape of water claims guide, both written for policyholders, and both useful to hand to an insured who is arguing with the process rather than the finding.

If you have a file open now and need a cause established this week, call 020 7123 8560. Standard detection is £160 an hour, trace and access is £200 an hour, most surveys take two to four hours, and the report follows within 48 hours of the visit.