--- title: "What is a 'competent person' for Legionella, and how do you prove it?" source_url: https://legionella.io/articles/what-is-a-competent-person-for-legionella-and-how-do-you-prove-it/ canonical_url: https://legionella.io/articles/what-is-a-competent-person-for-legionella-and-how-do-you-prove-it/ pillar: "UK Legionella Law & Compliance" summary: "A 'competent person' for Legionella is not a certificate. See what competence actually means, when you must appoint help, and the evidence inspectors look for." primary_keyword: "Legionella competent person" date_published: 2026-02-04 date_reviewed: 2026-06-26 author: "Legionella.io editorial team (REMOTE TECH LTD)" reviewed_against: "HSE L8 and HSG274 guidance" region: "United Kingdom" license: "(c) REMOTE TECH LTD. Quote freely with attribution and a link to source_url." --- # What is a 'competent person' for Legionella, and how do you prove it? A "competent person" for Legionella is someone with the right mix of training, knowledge, experience and ability to do a specific water-hygiene task properly. It is not a certificate, a job title, or a one-day course you sat in 2019. It is a match between a person and a task. That distinction matters because the law expects duty holders to appoint competent help, not just to own a folder of attendance slips [1]. An inspector does not ask "did someone go on a course?" They ask "can this person actually do the thing you needed them to do, and can you show me?" So the honest answer to "how do you prove it" is: with evidence that the person's competence fits the job they were given. Let me make that concrete. ## What "competent" actually means here HSE guidance frames competence as a combination of training, knowledge, experience and the ability to apply them appropriately to the task in hand [2]. Read that slowly, because every word is doing work. Training is the input. Knowledge is what stuck. Experience is having done it on real systems, not just heard about it. Ability is the judgement to know when something is off and what to do next. A person can have the first and badly lack the last. Competence is also task-specific. Someone perfectly competent to take a hot and cold temperature round and record it may be nowhere near competent to author a risk assessment, design a remedial scheme for a calorifier, or interpret a Legionella sample result. The question is never "is this person competent?" in the abstract. It is "competent to do what?" That is why "we sent the caretaker on a Legionella awareness course" answers a different question than the one being asked. Awareness training makes someone safer and more useful. It does not, on its own, make them competent to assess the risk of a complex building. ## How it plays out on a real site Take a mid-sized care home with a calorifier, several TMVs, a couple of little-used guest bathrooms that act as dead legs, and an outsourced water-treatment contractor. The duty holder appoints a **responsible person** in-house, usually the estates or facilities manager, to take day-to-day charge of the scheme. Their competence needs to be enough to run and oversee the controls: understand the written scheme, make sure flushing and temperature monitoring happen, spot when a reading drifts out of range, and know when to escalate [1]. They do not personally need to be a microbiologist. The **risk assessment** is authored by someone competent in assessment specifically, which often means an external assessor working to the relevant code of practice. Assessing a system you have never seen, identifying the dead legs, and judging proportionate control is a genuinely different skill from running the daily scheme. The **contractor** carries out specialist tasks: cleaning, disinfection, sampling, certain monitoring. Their competence is something you check, not assume, and registration schemes exist partly to help you do that [4]. Three roles, three different competence requirements, one site. Confusing them is where things go wrong. For more on who holds which role, see the related reading below. ## The one thing beginners get wrong The single most common mistake is treating a certificate as proof of competence. It is evidence, not proof. A training certificate tells you someone attended and, at best, passed an assessment on a given day. It says nothing about whether they have applied that knowledge since, whether the course covered your type of system, or whether their judgement has been tested on a live problem. Certificates also expire in relevance long before they expire on paper. The pragmatic call is to treat training records as one ingredient and back them with evidence of actual practice: who did what, when, with what result, and what they did when a reading went out of range. That trail is worth more to an inspector than any laminated card. ## How you prove competence to an inspector Here is what genuinely demonstrates competence when someone asks, in roughly the order it carries weight. A **named, documented appointment**. The responsible person is identified by name, with a written scope of what they are responsible for. "Someone in facilities" is not an appointment. **Training records that match the role**. Not just that training happened, but that its content fits the tasks the person actually does, with dates and refresher history. In my view this is where a digital record beats a drawer of certificates: you can show the role, the matching training, and the live task history in one place rather than reconstructing it under pressure. **Evidence of applied practice**. Completed temperature rounds, flushing logs, actions taken when controls failed, and who signed them. This is the part that separates a competent scheme from a paper one. **The risk assessment author's competence**. Who wrote it, against which code of practice, and what their basis for assessing was [2]. **Your checks on contractors**. How you satisfied yourself the service provider is competent, including registration where applicable [4]. If you can lay those five things out quickly, you are demonstrating competence in the way the regime expects: assessed, managed and recorded [3]. ### Is "competent" the same as "qualified"? No. Qualifications and certificates contribute to competence, but competence also needs current knowledge, real experience, and the ability to apply judgement to your specific systems [2]. A well-qualified person with no relevant experience may still not be competent for the task. ### Can one person be the competent person for everything? Rarely, and only on simple premises. On most sites competence is split: an in-house responsible person runs the scheme, a competent assessor writes the risk assessment, and a contractor handles specialist work. The duty holder's job is to make sure each task is matched to someone competent to do it [1]. ### Does appointing a competent contractor remove my legal duty? No. You can delegate the work; you cannot delegate the accountability. The duty holder remains responsible for ensuring the risk is assessed, managed and recorded, even when competent contractors do the hands-on tasks [3]. ## A necessary caveat Competence is judged against the specific task and the specific water systems in front of you, so nothing here replaces a competent, site-specific risk assessment that decides what your premises actually need. A person competent for a small office may be out of their depth on a healthcare or industrial system, and the reverse can be true too. Treat this as general guidance for understanding the term, not a ruling on who is competent for your building. ## What to do today Pick one role on your site and test it honestly: name the person, write down the tasks they are responsible for, and see whether your records show they can actually do those tasks. If the evidence is scattered across certificates, emails and a paper logbook, that is your signal. Pulling appointments, training records and task history into a single digital logbook turns "we think they're competent" into something you can show an inspector in minutes rather than days. ## Related reading - [Duty Holder and Responsible Person roles in Legionella management](https://legionella.io/articles/duty-holder-and-responsible-person-roles-in-legionella-management/) - [Training your team in Legionella awareness](https://legionella.io/articles/training-your-team-in-legionella-awareness/) - [Training staff for Legionella compliance: what is expected?](https://legionella.io/articles/training-staff-for-legionella-compliance-what-is-expected/) ## Sources [1] HSE, "Legionnaires' disease. The control of legionella bacteria in water systems - ACoP and guidance (L8)". https://www.hse.gov.uk/pubns/books/l8.htm [2] HSE, "Legionnaires' disease: Technical guidance (HSG274)". https://www.hse.gov.uk/pubns/books/hsg274.htm [3] HSE, "Legionnaires' disease - what you must do". https://www.hse.gov.uk/legionnaires/what-you-must-do/index.htm [4] Legionella Control Association, "Code of Conduct for Service Providers". https://www.legionellacontrol.org.uk/