24/7 Emergency Response
Tracer Gas Leak Detection London
A hidden leak is an urgent problem that gets worse by the minute, risking structural damage and high water bills. You need the leak found now, not tomorrow. We are London's 24-hour tracer gas leak detection specialists, deploying immediately to pinpoint the exact source.
Tracer gas leak detection costs in London
| Job | Typical cost | Time |
|---|---|---|
| Standard tracer gas survey, single accessible system | 250 to 400 pounds | 1 to 2 hours |
| Leak on plastic or under-screed pipework | 350 to 550 pounds | 2 to 3 hours |
| Combined tracer gas with thermal or acoustic methods | 400 to 650 pounds | 2 to 4 hours |
| Central heating or underfloor heating circuit | 300 to 600 pounds | 2 to 4 hours |
| Access and pinpoint excavation to expose leak | 150 to 400 pounds | 1 to 3 hours |
Typical UK trade cost-guide ranges, not a quote. Our detection fee is fixed and agreed at booking.
Tracer gas detection is the most accurate, non-invasive method for finding concealed water leaks under floors, behind walls, and in central heating systems. Our engineers arrive equipped and ready to work, day or night. The first action is to call us – we will guide you on any immediate isolation you can perform.
We work across London neighbourhoods where older properties and complex plumbing make leaks hard to find. From Victorian conversions in Islington to modern flats in Canary Wharf, our mobile detection teams respond without delay to stop the damage at its source.
Our pricing is based on a fixed site investigation fee for the detection service. There are no hidden charges, and we explain all costs before starting work. Emergency and out-of-hours callouts are priced transparently.
What you get
- 24/7 emergency deployment across London – we come to you, out-of-hours.
- Rapid, pinpoint accuracy for leaks under screed, concrete floors, and behind walls.
- Non-destructive method – avoids unnecessary digging or damage to your property.
- Effective on pressurised central heating systems and underfloor heating leaks.
- Immediate, clear results shown to you on-site with digital detection equipment.
- Follow-up report provided with evidence and location for your plumber to repair.
How it works
A method, not a guess
01
Your Emergency Call
Call us immediately. We will dispatch an engineer and advise on any urgent isolation of your water supply or heating system to minimise damage while we travel.
02
On-Site Assessment
Our engineer arrives fast to assess the suspected leak area, checking symptoms like damp patches, sound of water, or unexplained pressure drops in your system.
03
Gas Injection & Detection
We inject a safe, inert tracer gas into your plumbing. Using a sensitive sniffer probe, we track the gas as it escapes at the leak point, even through concrete or behind tiles.
04
Pinpoint & Report
We mark the exact leak location for you. You receive a clear report with findings, so repair work is targeted and minimises disruption.
Six things to know before you book tracer gas leak detection in London
Tracer gas sits at the top of the price range — understand why before you pay for it
Checkatrade puts UK tracer gas detection at £250 to £2,000, against £150 to £1,000 for thermal imaging. The premium is real: the 5% hydrogen mix is consumed on every job, the pipework or heating circuit usually has to be drained and pressurised, and the sniffer probes need calibration. What that means for you: never pay tracer gas rates for a leak that acoustic or thermal kit could find in twenty minutes. Ask any firm quoting for tracer gas which cheaper methods they will try first — and whether gas is included in the headline price or billed as an extra, which is a common small-print trick.
Hourly diagnostic rates are where budgets die
Trade cost guides show diagnostic work billed at £95 to £145 per hour, and tracer gas jobs are slow by nature: drain-down, gas injection, then a methodical sweep of floors and walls. A firm advertising £80 to £120 per hour can legitimately run to four or five hours — £400 to £700 before VAT — with no cap and no obligation to find anything. A fixed fee agreed at booking (typical London domestic surveys run £250 to £450) with a genuine no-find-no-fee usually costs less in practice, because the risk of a long search sits with the company, not with you.
Rule out the boiler before paying anyone to gas the pipes
The classic tracer gas job is a combi boiler losing pressure with no visible leak. But on DIY forums, a striking number of these threads end with the culprit inside the boiler — a waterlogged expansion vessel or a pressure relief valve discharging outside — not a buried pipe at all. A competent engineer isolates the heating circuit from the boiler and pressure-tests each circuit separately before introducing any gas. If the surveyor you book goes straight to tracer gas without that elimination step, you may be paying premium rates to search pipework that was never leaking.
The gas itself is safe — but ask the firm to confirm the mix
Professional tracer gas is 5% hydrogen in 95% nitrogen. At that concentration it is inert, non-toxic, odourless and non-flammable — well below hydrogen's 4% flammability threshold in air — and it is approved for use in drinking water pipes and occupied homes. The hydrogen molecule is the smallest in the atmosphere, so it escapes through even a pinhole and rises to the surface, where a calibrated detector picks it up through concrete and tiles. Any firm that cannot tell you the exact mix, or that proposes using anything else in potable pipework, should not be let near your plumbing.
Check your trace and access cover before you book — and tell your insurer first
Most UK buildings policies include trace and access cover, typically £5,000 and sometimes £10,000, which reimburses the cost of finding the leak and opening up to reach it — though not the pipe repair itself or always the reinstatement. Two traps catch homeowners: instructing a contractor before notifying the insurer, which can give grounds to refuse the claim, and receiving a one-line invoice instead of a proper report. Loss adjusters expect documented cause, origin, method and photographic evidence. Ask any firm to show you a sample trace and access report before booking; ours are structured for UK adjusters and delivered within 48 hours.
Read the small print on 'detection from £110' adverts
Low headline prices usually cover a brief single-method visit, with tracer gas, additional hours, access works and reinstatement all quoted separately. One documented case saw a homeowner pay £450 plus VAT for detection, then discover that opening the floor, the repair and making good were each a separate quote. Before booking, get written answers to five questions: is the fee fixed or time-based, is tracer gas included, what happens if no leak is found, is a photographic report included as standard, and are repairs quoted before any work starts. A firm that hesitates on any of these is telling you something.
Compare like for like
Tracer Gas Leak Detection Across London
Tracer gas is the method that finds leaks other tools cannot reach. A safe hydrogen-nitrogen mix is fed into the drained pipework, then a sensitive detector traces the escaping gas back to the exact point, even under screed or through solid floors. It is precise, minimally destructive and suited to plastic and buried pipe.
| What to check | A cheap hourly quote | A one-method firm | London Leak Specialist |
|---|---|---|---|
| When tracer gas decides | Rarely explained. A low hourly rate can mean cameras or listening only, which miss plastic pipe and leaks hidden beneath screed. | Applied to everything, even where acoustic or thermal work would locate the leak faster and at lower overall cost. | We reserve tracer gas for the cases it suits best: plastic pipework, buried lines and leaks under screed or solid floors. |
| Draining and preparing | Prep is often skipped or rushed, so gas cannot circulate correctly and the trace gives a vague or false result. | Prep happens but is treated as an afterthought, sometimes leaving the system poorly isolated before gas is introduced. | We drain and isolate the affected circuit properly, then charge it with tracer gas so readings are clean and repeatable. |
| Safety of the gas | Cut-price jobs may use unclear mixes or handle them casually, which is not something to accept indoors. | Usually competent, though safety detail varies with the individual rather than a consistent method. | We use a five percent hydrogen in ninety-five percent nitrogen mix: inert, non-toxic, non-flammable at that ratio and safe to trace inside homes. |
| Equipment quality | Basic or ageing detectors that struggle to isolate a single escape point, so guesswork fills the gap. | Good gas kit, but limited backup tools when the trace needs confirming by another method. | Calibrated hydrogen detectors backed by acoustic and thermal tools, so a suspected point is confirmed before anyone lifts a floor. |
| How pricing works | A tempting hourly headline that can climb as the visit drags, with add-ons appearing once work starts. | Often a flat method fee whether tracer gas is the right tool or not, which can cost you more overall. | Clear quotes within typical UK trade cost-guide ranges, agreed before we start, with no charges added on the day. |
| No find, no fee | Seldom offered, so you can pay in full for a visit that ends without the leak being located. | Sometimes offered, but tied only to the single method they use, which narrows your protection. | If our survey cannot pinpoint the leak, you do not pay the location fee. We stand behind the result. |
| Report for insurers | Little or no documentation, leaving you to argue a trace-and-access claim without written evidence. | A basic note of findings that may lack the detail an insurer wants for the claim. | A clear written report with findings, images and method, suitable for supporting a home insurance trace-and-access claim. |
From the forums
What Londoners say on Reddit & forums
London homeowners talk about hidden leaks constantly on Reddit and DIY forums — usually after a combi boiler starts losing pressure or a ceiling stain appears — and the threads are full of hard-won lessons about who to call, what it should cost, and what insurers actually pay for.
On r/DIYUK and DIY forums, homeowners chasing boilers that lose pressure overnight
The recurring advice in these threads is to do the free elimination work first: isolate the heating circuit at the boiler valves overnight, check whether the pressure still drops, and inspect the pressure relief discharge pipe and expansion vessel. A surprising share of posters report the 'hidden pipe leak' turned out to be inside the boiler itself. Our take: this is exactly right, and it is why a proper survey pressure-tests each circuit separately before anyone reaches for tracer gas — it protects you from paying premium rates to search pipes that were never leaking.
In r/HousingUK-style discussions about escape of water insurance claims
Homeowners are routinely surprised to learn that trace and access cover — typically £5,000 on standard policies — pays for finding the leak and opening up to reach it, but not the pipe repair, and sometimes not putting floors and walls back either. The other repeated warning is procedural: people who instructed a contractor before notifying their insurer found the claim questioned or refused. Our take: call your insurer before booking anyone, and insist on a detection firm whose report documents cause, origin and method, because that document is what the adjuster actually assesses.
Forum complaints about single-method call-outs that found nothing
A common grievance is paying a call-out fee for an engineer who arrived with one piece of kit — usually a thermal camera or a listening stick — swept the room, declared the leak untraceable and left, with the fee still owed. The consensus advice is to ask before booking exactly what equipment the firm carries and what happens to the fee if nothing is found. Our take: fair challenge. No single method finds every leak, which is why acoustic, thermal, tracer gas, moisture mapping and per-circuit pressure testing should all arrive on the same van, on every visit.
Homeowners asking whether pumping gas into their pipes is actually safe
The question comes up regularly from people who hear 'hydrogen' and picture something flammable in their drinking water pipes. Forum answers consistently reassure: the professional mix is 5% hydrogen in 95% nitrogen, which is inert, non-toxic and sits far below hydrogen's flammability threshold, and it is approved for potable water systems. Our take: the reassurance is correct, but the caveat matters — safety depends on the operator using the certified 5/95 mix and venting the system properly afterwards, so ask the firm to confirm both before they connect anything.
Cost-shock threads comparing wildly different leak detection quotes
Posters comparing quotes for the same suspected leak report spreads from under £200 to well over £1,000, and the thread wisdom is consistent: cheap hourly quotes grow with every hour on site, while a higher fixed quote is often cheaper by the end of the day. The most recommended questions are whether the price is capped, whether a written report with photos is included, and what happens if no leak is found. Our take: the market data backs this up — diagnostic hourly rates run £95 to £145, so anything beyond three hours overtakes most fixed-fee surveys.
Questions
Asked before every booking
When should I call for tracer gas detection?
Call immediately if you have signs of a hidden leak: a constantly running water meter, damp patches spreading on floors or walls, or a loss of pressure in your heating system with no visible leak. The faster we locate it, the less damage occurs.
How quickly can you get to me in London?
We operate 24/7 with mobile teams across London. We aim to be on the road to you within the hour for urgent cases, including nights and weekends. Call us with your location for an accurate ETA.
Is tracer gas safe for my home and family?
Yes. We use an inert, non-toxic, non-flammable gas (typically a hydrogen-nitrogen mix) approved for leak detection. It leaves no residue or odour and is completely safe for occupants, pets, and plumbing systems.
Can you find leaks in underfloor heating?
Absolutely. Tracer gas is highly effective for pressurised systems like underfloor heating. The gas escapes with the water through the smallest puncture in the pipes, allowing us to pinpoint the leak accurately without removing the entire floor screed.
What do I need to do before you arrive?
If safe to do so, isolate the water supply to the suspected area to slow the leak. Have access to the water meter and any underfloor areas like cupboards ready. Most importantly, call us first – we will guide you through immediate steps.
How much does tracer gas leak detection cost in the UK?
Checkatrade puts tracer gas detection at £250 to £2,000, reflecting drain-down time, consumable gas and calibrated detectors. Full-day specialist surveys are commonly priced around £595 plus VAT, while hourly diagnostic work runs £95 to £145 per hour. In London, a fixed-fee domestic detection visit combining tracer gas with acoustic, thermal and pressure testing typically costs £250 to £450, agreed before the engineer attends. If your buildings policy includes trace and access cover, the detection cost is usually reimbursable.
Is tracer gas safe to use in drinking water pipes?
Yes. Professional tracer gas is 5% hydrogen mixed with 95% nitrogen — inert, non-toxic, odourless and non-corrosive. At that concentration it cannot ignite, sitting well below hydrogen's 4% flammability threshold in air, and it is approved for use in potable water systems and occupied homes. The gas simply escapes through the leak, rises through floors or walls, and is picked up by a calibrated detector on the surface. The system is vented afterwards and no residue remains.
How long does tracer gas leak detection take?
Most domestic tracer gas surveys take one to three hours, with complex properties or multiple suspect circuits running up to six. The pipework or heating system usually needs draining first so the gas can travel to the leak, which adds time compared with acoustic or thermal methods. A straightforward job in a London terrace or semi is typically completed within a half-day visit, including per-circuit pressure testing to confirm which system is actually losing water.
Does home insurance cover tracer gas leak detection?
Usually, yes — through trace and access cover, included on most UK buildings policies with limits of typically £5,000 and sometimes £10,000. It pays for locating the leak and opening up to reach it, but not the pipe repair itself, and reinstatement cover varies by policy. Notify your insurer before instructing a contractor, as claiming retrospectively can be refused, and make sure the detection firm provides a proper report documenting cause, origin, method and photographs for the loss adjuster.
When is tracer gas needed instead of acoustic or thermal leak detection?
Tracer gas is the method of last resort — and often the only one that works. It is used when a leak is too small or slow to make detectable noise, when there is no temperature difference for a thermal camera to see, and on plastic pipework, underfloor heating, buried mains and screeded floors where acoustic kit struggles. Because hydrogen escapes through pinholes and passes through concrete, it can locate weeping joints that every other method misses.
London-wide
Covering all 33 boroughs
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.
Book a detection visit