No Find, No Fee Leak Detection: What It Really Means (and the Small Print to Check)

Few phrases in the trade feel as reassuring as no find, no fee. You have a damp patch spreading across a ceiling, a water bill that has doubled for no obvious reason, or a boiler that keeps losing pressure. Someone offers to come out and locate the leak, and if they cannot find it, you pay nothing. On the surface it removes all the risk. In practice, the phrase is only as good as the definitions sitting underneath it, and those definitions vary enormously from one firm to the next.

This guide explains what no find, no fee genuinely means, where the small print tends to hide, and the exact questions to ask before you let anyone through the door. The goal is not to make you cynical. A properly worded guarantee is one of the best tools you have for keeping diagnosis honest. But you need to know what you are actually agreeing to, because a poorly worded one can leave you paying a full fee for a leak that was never really pinned down.

What no find, no fee is supposed to mean

The plain-English promise is simple. A leak detection engineer attends, uses non-destructive equipment to trace the source of the water, and only charges you if they succeed. If they leave without an answer, there is no charge for the visit. It exists because leak detection is a diagnostic service, not a guaranteed-outcome one, and the guarantee is the firm's way of putting its own skill on the line rather than yours.

Detection relies on a spread of tools rather than a single magic device. Acoustic listening equipment picks up the sound of water escaping under pressure. Thermal imaging cameras read temperature differences where warm or cold water tracks through a floor or wall. Tracer gas, a safe hydrogen and nitrogen mix, is introduced into a drained pipe and rises to the surface where it escapes, giving a precise exit point. Moisture meters, pressure testing and drain cameras fill in the rest. A skilled engineer chooses the right combination for the property and the symptom.

Because no single method works everywhere, an honest guarantee accepts that some jobs are genuinely harder than others. The firm is effectively saying: we are confident enough in our kit and our people that we will absorb the cost of the rare failure. That confidence is exactly what you are paying for. The problem starts when a firm wants the marketing benefit of the promise without the financial exposure that should come with it, and quietly rewrites the terms so that almost every visit ends in a bill.

The carve-outs that quietly reintroduce a charge

Most disputes do not come from firms breaking their promise outright. They come from a promise that was narrower than it appeared. Here are the carve-outs that appear most often, and why each one matters.

Excluding heating circuits and the incoming mains

A common exclusion is that the guarantee applies only to certain pipework. Some firms cover hot and cold plumbing but exclude the central heating circuit, or exclude the incoming water main from the boundary to the property. These are not obscure edge cases. Pressurised heating systems that keep losing pressure, and buried mains supplies running under a drive or garden, are two of the most frequent reasons people call in the first place. If the guarantee excludes exactly the systems most likely to be leaking, the promise is close to meaningless for a large share of real jobs.

Defining "found" as a vague area rather than a point

This is the most important small-print issue and the one people notice too late. Ask what counts as having found the leak. A genuine result narrows the source to a specific, repairable point, close enough that a repair can be made without demolishing half a room. A weak definition treats the leak as found if it has been located to a broad zone, sometimes described as something like a five metre by five metre area. Twenty-five square metres of floor is not a located leak. It is a starting point for guesswork, and you may still face a large bill for lifting flooring across the whole zone to discover where the water actually is.

Charging for time on site or a report regardless

Some firms honour the no-fee promise on the detection itself but attach a separate, non-refundable charge that applies whatever happens: a call-out fee, an hourly time-on-site rate, or a fixed charge for a written report or an insurance-ready document. The headline says no find, no fee. The invoice says you owe for two hours plus a report. Both can be technically true at once, which is precisely why you have to ask what is genuinely at risk if nothing is found.

Only honouring it if you also pay for intrusive access

Another pattern makes the guarantee conditional on buying more work. The engineer says the leak cannot be confirmed without lifting tiles, cutting into a wall or breaking up a section of floor, and the no-fee promise only stands if you authorise that chargeable trace and access work. In effect the guarantee is used as a lever: agree to the paid excavation, or the free part evaporates. Access work is sometimes genuinely necessary, but it should be a transparent, separately quoted decision, not a trapdoor built into the guarantee.

Charging the "wrong" leak in full

Properties can have more than one problem at once. A firm may locate a minor drip, declare the visit a success, charge the full fee, and leave the main leak, the one you actually called about, untouched or attributed to a different excluded category. You paid, something was found, and yet your original problem is unsolved. A fair process fixes the scope to the symptom you reported and is clear about what happens if multiple issues turn up.

What the forums and reviews actually say

If you read through consumer review sites, money-saving forums and DIY communities where people compare notes on tradespeople, a consistent pattern emerges around this phrase. It is worth summarising honestly, without inventing figures or quotes, because the lived experience is instructive.

The recurring complaint on review platforms is not that firms vanish with the deposit. It is the gap between the advertised promise and the final invoice. People describe booking specifically because of a no find, no fee headline, then being billed anyway because the leak turned out to be on the heating circuit or the incoming main, which sat outside the covered pipework. The frustration is sharpest when that exclusion was never spelled out on the call and only surfaced on the paperwork.

On money-saving and DIY forums, the repeated advice from people who have been through it is strikingly practical. Get the definition of "found" in writing before booking. Ask whether the call-out and any report are chargeable independently of the result. Confirm in advance whether central heating and the external supply are included. Contributors also warn about the reverse problem: a leak located only to a broad area, followed by a bill for extensive access work to find the actual point, which rather defeats the purpose of paying for detection in the first place. A further theme is the "wrong leak" scenario, where a small incidental issue is found and charged in full while the reported problem remains.

The reasonable takeaway from all of this is not that the guarantee is a scam. Plenty of people report clean, fair experiences. It is that the phrase alone tells you very little. The value lives entirely in the definitions, and the people who avoided a nasty surprise are almost always the ones who asked for those definitions up front.

The questions to ask before you book

You can defuse nearly every one of the problems above with a short conversation before anyone is booked in. Use the table below as a checklist. The left column is what to ask, the middle is the answer that should reassure you, and the right is the answer that should make you pause.

If a firm answers these clearly and puts the key points in writing, you are almost certainly dealing with a straight operation. If the answers are vague, or you are told not to worry about the detail, treat that as information in itself.

How a genuine version works

A genuine no find, no fee arrangement is refreshingly boring, because everything is settled before the van arrives. Here is what that looks like in practice.

• Exclusions stated up front. If there is any limit on what is covered, you hear it on the first call, not on the invoice. In most cases there is no reason to carve out heating circuits or the incoming main; a capable engineer has methods for all of them.
• "Found" means a repairable point. The leak is located precisely enough to mark on the floor or wall, so a repair can be made in a contained spot rather than by opening up an entire room.
• A fixed fee agreed at booking. You know the number before work starts. It does not drift upward once someone is on site, and there is no separate call-out or report charge waiting in the wings.
• No fee genuinely means no fee. On the rare occasion a leak cannot be located, you pay nothing. That risk sits with the firm, where it belongs.
• Access work is separate and transparent. If lifting a floor or opening a wall is genuinely needed, it is quoted as its own line and it is your decision, never a condition attached to the guarantee.

This is the approach we take. The guarantee is stated in plain terms, any limits are disclosed before booking, the leak is traced to a point you can actually repair, and the fee is fixed when you book rather than negotiated once we are standing in your hallway. You can see how that translates into numbers on our pricing page.

Why an honest guarantee keeps diagnosis honest

There is a deeper reason a genuine guarantee matters, beyond protecting your wallet on a single visit. When a firm only gets paid for actually finding the leak, its incentives line up with yours. The engineer is motivated to keep testing until the source is pinned down, because a vague answer earns nothing. That pressure is exactly what you want when the alternative is someone guessing, opening up a floor on a hunch, and billing you for the exploratory damage.

Weaken the guarantee with carve-outs and time charges, and you invert those incentives. If the firm gets paid whether or not it succeeds, there is far less to lose by declaring a broad area, charging for the visit, and leaving the precise work to whoever comes next. The small print, in other words, is not a technicality. It is the mechanism that decides whether the person diagnosing your leak is rewarded for being right or simply for turning up.

So treat no find, no fee as the beginning of the conversation rather than the end of it. Ask what "found" means. Ask what is excluded. Ask whether the fee is fixed and whether anything is chargeable regardless of outcome. A firm that welcomes those questions and answers them in writing is one whose guarantee is worth having. When you are ready, our London leak detection team is happy to walk through the terms before you commit to anything.

Typical UK cost-guide ranges

Prices vary by property, access and the methods needed, so treat the following as typical UK trade cost-guide ranges rather than quotes. A non-destructive leak detection visit commonly falls somewhere in the region of 200 to 500 pounds, depending on the size of the property and the equipment required. Where a report is needed for an insurance claim, that may be included or priced separately, so confirm which applies. Trace and access work, meaning the controlled lifting or opening needed to reach a confirmed leak, is a separate cost and depends heavily on the finish involved. The important point is not the exact figure but that you agree it, in writing, before work begins.