Technical Answers: John Mayer
Gas, Heating & Leak Detection Engineer | PrimeFix
Last Updated
October 2026
Most residential leak detection surveys take one to two hours. At PrimeFix that works out at £120 +VAT for a one-hour survey, or £240 +VAT for two hours. There’s no call-out fee, and you get a written report you can use for an insurance claim. The final cost depends on the type of leak, the size of the property and how easy the pipework is to reach.
A leak you can’t see is stressful enough without guessing what it will cost to find. Some firms quote a flat fee, some charge by the hour, and many won’t give a figure until they’re through the door. This guide explains how leak detection is priced, what a typical survey costs, and what decides whether yours lands at the low or high end.
If you’d rather skip ahead and book, our non-destructive leak detection service covers London and the Home Counties, 24/7.
There are two common pricing models in the UK.
You pay one price for the survey regardless of how long it takes. It sounds simple, but the fee is set high enough to cover the difficult jobs, so you pay that margin even when the leak takes 40 minutes to find.
You pay for the time the engineer spends on site. Simple jobs cost less, and you only pay more when the leak genuinely takes longer to trace.
At PrimeFix, we charge hourly. The first hour is £120 +VAT. After that, time is billed in half-hour blocks of £60 +VAT. You can see the full breakdown on our hourly rates page.
From a practical point of view, I wouldn’t put every leak into a fixed ranking, because the layout of the property and the symptoms can make a big difference. But generally, this is how I’d approach the common ones.
A central heating leak can be relatively straightforward if the boiler keeps losing pressure and we can isolate the heating circuits. That gives us a useful starting point.
A shower or bath waste leak can also be fairly quick to investigate if we can reproduce the leak and establish whether it’s coming from the waste, a connection or the surrounding seals. The challenge is that water can travel along a floor or behind tiles before it appears somewhere else.
An incoming mains water leak can take longer, particularly if the pipe runs beneath concrete or outside the property. We may need to use pressure testing and acoustic equipment to narrow down the location.
Underfloor heating leaks can be more involved because the pipework is buried beneath the floor. We need to identify the affected circuit and pinpoint the leak as accurately as possible before anyone considers opening the floor.
An external supply pipe leak can be one of the harder jobs, especially when the pipe is underground, the route isn’t known or the ground is wet over a wide area.
The main thing is to use the right test for the problem rather than jump straight to one detection method. We want to find the source accurately and avoid unnecessary damage.
| Survey length | Cost +VAT | Cost inc. VAT |
|---|---|---|
| 1 hour | £120 | £144 |
| 1.5 hours | £180 | £216 |
| 2 hours | £240 | £288 |
| 3 hours | £360 | £432 |
First hour £120 +VAT, then £60 +VAT per half-hour. No call-out fee.
Most homes fall in the one to two hour range. Longer surveys are usually larger properties, complex heating systems or leaks that only show up under tracer gas.
A lot depends on the type of leak and how much information we have before arriving. If the symptoms point clearly towards one pipe or one heating circuit, we can sometimes narrow things down quite quickly. If the leak is beneath a concrete floor or only shows up intermittently, it can take longer.
I wouldn’t give a percentage for jobs completed in the first hour without checking our actual job records. I’d rather give a customer a realistic expectation than quote a figure that isn’t backed up by our experience.
Our standard leak detection rate is £120 plus VAT for the first hour, followed by £60 plus VAT for each additional half-hour. We explain the pricing before starting, and there’s no call-out fee.
As for the longest survey, that is something I’d want to confirm from our job records before quoting a specific example. The important point is that a complicated investigation can take several hours, particularly when there are multiple pipe circuits, difficult access or a leak that requires more than one testing method.
A central heating leak that’s making the boiler lose pressure is often quicker to isolate than a leak on the incoming mains, because the system can be pressure-tested circuit by circuit. Leaks under screeded floors or in underfloor heating usually take longer.
Thermal imaging and moisture readings are quick to deploy. Acoustic tracing takes a little longer. Tracer gas is the most precise method, and we use it for leaks nothing else can pinpoint, so it tends to add time. You can read how each method works on our leak detection page.
A one-bed flat with pipework in one run is quicker to survey than a four-storey Victorian terrace with decades of alterations. Period properties across London often have pipework that doesn’t follow any drawing.
If the engineer can get to the stopcock, boiler, manifold and meter straight away, the survey starts immediately. Locked cupboards, boxed-in pipework or a meter you can’t find all add time.
Photos, a description of the damp patch and how long it’s been there, and whether your water bill or boiler pressure has changed all help the engineer arrive with a plan. You can upload photos when you book.
Older London properties can be challenging because the plumbing has often been altered several times over the years. You might find original pipework alongside newer installations, extensions or repairs that were never properly documented.
In some houses, pipes run beneath suspended timber floors. In others, they’re buried in concrete, boxed into walls or routed through awkward spaces. Victorian terraces and converted flats can have particularly complicated layouts.
Another issue is that the visible damp patch isn’t necessarily close to the leak. Water can travel along a joist, follow a pipe or collect at a low point before appearing on a ceiling or wall. That’s why we don’t automatically assume the wettest area is the source.
We start by looking at the symptoms, checking accessible pipework and using the appropriate detection equipment. Depending on the situation, that might involve moisture readings, thermal imaging, pressure testing, acoustic tracing or tracer gas.
The aim is to narrow down the source before any opening-up work takes place. The more accurately we can locate the leak, the less unnecessary disruption the customer is likely to face.
Sometimes a leak can be difficult to locate on the first visit. It might be intermittent, only occur when a particular appliance is running, or be hidden beneath a floor where access is limited.
If that happens, I explain what we’ve tested, what the results tell us and what remains uncertain. We then discuss the next sensible step. That could mean testing another circuit, using a different detection method or arranging a follow-up investigation.
We don’t want to recommend unnecessary work or start opening floors and walls without a clear reason.
Our standard pricing is £120 plus VAT for the first hour and £60 plus VAT for each additional half-hour. If another visit or further investigation is needed, the expected cost should be explained before proceeding. The customer pays for the time and work carried out under the agreed terms; we don’t promise that every leak can be found within a single visit.
If the customer is making an insurance claim, I’d also recommend checking with the insurer before authorising additional investigation, as the policy may set conditions around approval and reimbursement.
Often, yes. Many UK home insurance policies include “trace and access” cover. It pays for finding the source of an escape of water and for the work needed to reach it, such as lifting floorboards or opening a section of wall. It doesn’t always cover the repair to the pipe itself.
Cover limits and conditions vary between policies, so check yours or call your insurer before booking. Most insurers want evidence of where the leak was and how it was found. That’s what our report is written to provide.
Detection and repair are separate, but we can usually do both on the same visit. Repair time is charged at the same hourly rate, and materials are charged at trade cost plus 30%, itemised on your invoice. We diagnose first and confirm the repair cost with you before any work starts.
A low headline price means little if the leak isn’t found. One of our customers was losing more than 40 litres of water a day. A previous firm had sent two engineers on repeat visits, spent thousands and never found the source. Our engineer found it in a couple of hours and left a written report with photos for the insurer.
Every week a hidden leak runs, it adds to water bills, damp damage and repair costs. Paying for the right equipment and an experienced engineer the first time is usually the lower-cost route.
They generally need to understand three things: what the problem is, how we identified it and what needs to happen next.
A useful report should explain the customer’s original symptoms, the areas investigated, the tests carried out and the results. Where relevant, we include photographs, moisture readings, pressure test findings, thermal images and details of the confirmed or suspected leak location.
We also explain our technical conclusion and recommend the next steps. If access is required, the report should make clear why it is needed and where the investigation indicates the opening-up work should take place.
A report that simply says there’s a leak, without supporting evidence, can lead to further questions and delays. The insurer may need more photographs, test results or clarification before assessing the claim.
We aim to provide a clear, factual record of the investigation so the customer and the insurer can understand what we’ve found. The insurer ultimately decides whether the work is covered under the policy, so a report can support a claim but cannot guarantee acceptance.
If we can locate the leak, access the pipework and carry out the repair safely, we can often complete the repair during the same visit. A leaking accessible joint or a straightforward section of pipework may not require a separate appointment.
It’s a different situation if the pipe is beneath a concrete floor, behind a tiled wall or inside a section of the building that needs specialist opening-up work. We may also need specific replacement parts, specialist equipment or another trade before the repair can be completed.
Sometimes the immediate priority is to isolate the affected pipe or stop further water escaping, then plan the permanent repair once the source has been confirmed.
Detection and repair are separate parts of the job, so we explain the proposed repair and its cost before carrying out additional work. Our aim is to resolve the problem with as little disruption as reasonably possible, without rushing a repair that needs more preparation.
One example I’d like to share is a job involving a property where the customer was losing more than 40 litres of water a day. Previous visits by another company hadn’t identified the source, despite repeat attendance and significant expenditure.
Our engineer investigated the problem using specialist leak detection methods, located the source within a couple of hours and provided a written report with photographs for the insurer.
The important part wasn’t just finding the leak. It was being able to show the customer where the problem was and provide evidence to support the next stage of the repair and insurance process.
A leak that continues for weeks can increase water bills and allow moisture damage to spread. Finding it sooner can help limit those additional costs and reduce the amount of disruption involved.
Turn off every tap and water-using appliance, take a reading from your water meter, wait 30 minutes without using any water, then read it again. If the number has moved, water is escaping somewhere on your supply.
If it keeps dropping and you’re topping it up, write down how often. That points the engineer towards the heating system.
Make sure the stopcock, boiler, meter and any underfloor heating manifold are reachable.
Damp patches, stains and the age of the problem all help the engineer plan the survey.
Exploratory damage can make the leak harder to trace and may complicate an insurance claim.
One of the biggest problems is when someone starts lifting floorboards, removing tiles or opening up a wall because they think they’ve found where the leak is.
I understand why people do it. They’re worried about the damage and want to get to the pipe as quickly as possible. But the visible damp patch isn’t always where the water is escaping, and opening the wrong area can create more damage without helping us find the source.
It can also complicate the investigation because we’ve lost some of the original evidence of where the moisture was appearing.
Before we arrive, I’d suggest taking photographs of the damp area, noting when the problem first appeared and telling us whether the boiler pressure has dropped, the water bill has increased or the leak only happens when a shower or appliance is used.
If it’s safe and practical, make sure the stopcock, boiler, water meter and any underfloor heating manifold are accessible.
If water is actively escaping, prioritise safety and stop the water supply if you can do so safely. Don’t touch electrical equipment or fittings that may be wet.
Those simple steps give us a much better starting point and help us spend our time investigating the actual problem.
Yes. The first hour, £120 +VAT, is the minimum. After that, time is charged in half-hour blocks.
No. All our published rates are +VAT. A one-hour survey costs £144 including VAT.
We can give you a realistic estimate of time when you book, based on what you tell us. We confirm costs in writing before any repair work starts. A truly fixed price isn’t possible for detection, because nobody knows exactly where the leak is until it’s found.
For emergencies, an engineer is typically on site within one to three hours, 24/7.
Call 0208 108 0400, message us on WhatsApp, or book a leak detection engineer online. You’ll get a confirmed price before any repair starts, and a written report at the end.
Landlords, HMO owners and managing agents with several properties can get discounted portfolio rates and priority response through our account client programme.
Commercial sites such as schools, offices, warehouses and care homes are priced differently, because survey scope, out-of-hours working and underground mains detection vary widely. See our commercial leak detection service for details.