Put every quote on the same scope before you compare a single price. The gap between one quote and another three times its size is rarely profit — it is usually what the cheaper one left out: outlets it never counted, a site visit it swapped for a desktop review, an asset register it does not include. Match the scope first, and the real price comparison falls out of that.
You are not actually choosing between two prices. To compare Legionella risk assessment quotes fairly, you are comparing two pieces of work that happen to share a title — and only once you can see what each provider has promised to do on site does comparing the bottom lines mean anything.
Two quotes for “the same building” are rarely the same job
A risk assessment is priced on effort: skilled time walking your system asset by asset, plus the report that follows. So the figure tracks how much of your system the provider intends to inspect, not your floor area. A quote that assumes 15 outlets and one that has counted 80 cannot land in the same place, even for the identical premises.
This is why the cheapest is so often a false economy. A cheap Legionella risk assessment is not automatically a bad one — but low quotes rarely win on efficiency. They win by narrowing scope: fewer outlets, a desk review instead of a survey, a thinner report. The narrowing is usually invisible on the page until you go looking for it. So stop reading quotes as prices and start reading them as scopes.
A like-for-like comparison framework
Pull these line items out of every quote and lay them side by side. Where a quote is silent on one, that silence is the answer — ask the question in the third column before you compare any figures.
| Line item to extract | Why it changes the price | Ask if the quote is silent |
|---|---|---|
| Survey type | A full site survey costs more than a desktop or self-completed form | ”Is this a physical site survey by a competent assessor, or a remote review?” |
| Outlet count basis | Each outlet is a thing to find, log and assess; an assumed count hides scope | ”How many outlets have you allowed for, and how did you arrive at that?” |
| Systems covered | Calorifiers, TMVs, showers, cold storage and any cooling plant each add work | ”Which systems are in and out of scope on my site?” |
| Buildings, floors, plant rooms | Each separate area needs its own walk-round and schematic | ”Does the price cover every block and plant room, or just the main building?” |
| Asset register and schematic | Building these from scratch is slow; omitting them is the commonest cut | ”Will I receive a populated asset register and a system schematic?” |
| On-site temperature checks | Representative readings on the day take time but evidence the findings | ”Will you take and record temperatures at representative outlets during the survey?” |
| Report deliverable | A flat risk rating is cheaper than asset-level, prioritised actions | ”Will recommendations be tied to specific assets and ranked by risk with timescales?” |
| Named assessor and method | Competence and a recognised method are what you are buying | ”Who surveys my site, and do you assess to BS 8580-1?” |
The decisive move comes last. Take the scope from the most thorough quote and ask the cheapest provider to re-quote against it, line for line. Either their price rises to meet the work — in which case you now have a genuine comparison — or it does not, which tells you the saving depended entirely on doing less. Either way you have turned three incomparable numbers into one fair decision. For vetting the firms themselves rather than the quotes, see How to choose a Legionella risk assessment company (questions to ask).
Desktop versus full survey: the biggest hidden swap
The largest single difference between a cheap quote and a thorough one is often the survey type. A full assessment is a competent person physically walking your system, opening plant-room doors, counting outlets and taking temperatures. A desktop or self-completed assessment is a questionnaire — useful as a record of what you already know, but it cannot find the dead leg behind a boxed-in riser or verify a stored-water temperature it never measured.
For anything beyond a genuinely simple, low-risk premises, the expectation is a competent assessment of your actual system [1]. A form emailed to you, completed at your desk, is not that. If one quote is cheap because it is really a desktop exercise dressed as a survey, you are comparing a survey with a substitute for one. Whether to handle this yourself or commission it out deserves an honest weighing, which In-house vs professional Legionella risk assessments sets out.
What a thorough assessment actually includes
To judge whether a low quote is lean or simply incomplete, measure its deliverables against what a competent assessment is expected to produce. Working to the code of practice, BS 8580-1, and the technical guidance in HSG274, a usable report should contain [2][3]:
- a description and schematic of the water systems;
- a populated asset register;
- an evaluation of the risk for each part of the system;
- dead legs, stagnation points and little-used outlets identified by location, not in the abstract;
- recordings of stored and distributed water temperatures taken on the day;
- prioritised, risk-ranked recommendations precise enough to assign and date;
- the assessor’s name and the date.
A quote whose deliverables stop at “a written risk assessment with a risk rating” is not cheaper than one promising the list above — it is smaller. The missing items are exactly the ones you need to build a control scheme, and the ones an enforcing officer will ask to see. A thin assessment that overlooks an asset is also how problems begin: Risk assessment errors that lead to Legionella growth walks through what gets missed and what follows.
Red flags in a suspiciously low quote
Treat these as scope gaps to probe, not accusations — ask, and a sound provider will explain readily.
- A firm fixed price quoted before anyone asked how many outlets or systems you have.
- A “risk assessment” that turns out to be a form for you to complete.
- No asset register or schematic anywhere in the deliverables.
- A single building-wide risk rating with no asset-level findings.
- A same-day or next-day turnaround offered for a multi-building site.
- Recommendations with no priority order and no timescales.
- Reluctance to name the person who will actually carry out the survey.
None of these proves a provider is cutting corners. Each is a question you are entitled to ask, and the answers separate a lean-but-complete quote from one that is cheap because it is incomplete.
A note on what this guidance can and cannot do
This is general help for comparing quotes fairly, not legal advice, and it does not set a price or a scope for your premises. The outlets, systems, frequencies and priorities that belong in your assessment come from a competent person who has seen your building and worked to BS 8580-1 on it — and the duty to assess, and to act on the findings, stays with you as duty holder even when a contractor does the survey [1][4]. The relative quote sizes described here are illustrative; only current written quotes built on an identical brief are truly comparable.
The step that makes every quote comparable
Before you reply to any provider, write a one-page scope brief: an estimated outlet count, a list of your systems (cold storage, stored hot water and calorifiers, TMVs, showers, any cooling plant), the number of buildings and plant rooms, and which schematics you already hold. Send the same brief to everyone and ask each to price against it line by line. That single page does more to expose a false economy than any amount of haggling — and the asset list at the heart of it drops straight into a digital logbook, so the assessment you eventually buy starts life as a live record rather than a PDF in a shared drive. If you want to understand what moves the figure before you send the brief, How much does a Legionella risk assessment cost in the UK? breaks down the drivers.
FAQ
Why is one Legionella risk assessment quote a third of the price of another?
Almost always because the scope differs, not the building. The cheap quote may assume far fewer outlets, swap a site survey for a desktop form, omit the asset register and schematic, or budget a single visit where your access needs two. Put both quotes on an identical outlet-and-system brief and the gap usually shrinks — or it reveals that the low price bought a much smaller job.
Is a cheaper desktop or remote risk assessment ever acceptable?
For a very simple, low-risk premises with a competent person on hand, a desk-based assessment may be proportionate. For anything with stored hot water, a calorifier, TMVs, showers or multiple buildings, treat it with caution: the expectation is a competent assessment of your actual system, and an outlet count or a hidden dead leg cannot be verified from a form [1]. The saving tends to vanish the moment you re-survey to fill the gaps.
The cheap quote left out the asset register — does that matter?
Yes, more than almost any other omission. The asset register and schematic are what turn a risk rating into something you can act on, monitor against and defend at audit. A report without them tells you that you have risk but not where, which leaves you unable to scope flushing, monitoring or remedial work [2]. A quote that excludes the register is not cheaper than one that includes it; it is doing less of the job.
Sources
[1] HSE, “Legionnaires’ disease - what you must do”. https://www.hse.gov.uk/legionnaires/what-you-must-do/index.htm [2] BSI, “BS 8580-1:2019 - Risk assessments for Legionella control. Code of practice”. https://knowledge.bsigroup.com/products/water-quality-risk-assessments-for-legionella-control-code-of-practice-1 [3] HSE, “Legionnaires’ disease: Technical guidance (HSG274)”. https://www.hse.gov.uk/pubns/books/hsg274.htm [4] HSE, “Legionnaires’ disease. The control of legionella bacteria in water systems - Approved Code of Practice and guidance (L8)”. https://www.hse.gov.uk/pubns/books/l8.htm