Who is responsible for a legionella risk assessment?
Updated 16 August 2026
Short answer
The duty sits with whoever has control of the premises or the water system. That is usually the employer, the owner, the landlord, or the managing agent. You can hire a water hygiene contractor to do the assessment, but the legal responsibility stays with you.
The Health and Safety at Work Act 1974 places general duties on employers and on those in control of non-domestic premises to protect people from health risks. ACOP L8 explains how those duties apply specifically to legionella. The effect is that there is always someone in scope, for almost every building type.
Employers
If you employ staff on the premises, section 2 of the Act makes you responsible for their health and safety, and section 3 extends that to anyone else who may be affected by your undertaking. Both apply to legionella exposure from your water system.
Landlords
Residential landlords are duty holders under section 3(2) of the Act in respect of their tenants. This is true even for single domestic lets, and even where the tenant has day-to-day use of the property. The duty is modest for a simple system with a combi boiler, but it is a real legal duty.
Building owners and managing agents
Section 4 of the Act creates duties for anyone with control of non-domestic premises. In a multi-tenanted office building, the freeholder or managing agent is usually responsible for the shared water system, and each tenant is responsible for the system within their own demise. The lease should say so explicitly.
The named "responsible person"
ACOP L8 requires the duty holder to appoint a named individual to be the responsible person for the water system. This is an internal appointment, not a job title that needs external certification. The appointee must have sufficient authority and competence to manage the scheme. In a small business this is often the owner. In a larger organisation it is typically a facilities manager, estates director, or designated compliance lead.
You cannot contract the duty out
You can engage a Legionella Control Association registered contractor to do the assessment, run the monitoring, and take samples. What you cannot do is transfer the legal duty. If something goes wrong, the HSE will come to you, not to the contractor.
Legal basis
Health and Safety at Work Act 1974 sections 2, 3, and 4. ACOP L8 paragraphs 26 to 30 on the duty holder and paragraphs 31 to 39 on the responsible person. HSG274 Part 2 section 1.3 on roles and responsibilities.
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Free legionella risk assessment template
A structured Word document following the five-step approach in ACOP L8. Covers risk identification, written scheme, monitoring, and records. If it isn't written down, you can't evidence it.
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