Who Is the Legionella Responsible Person? Duties, Liability and Delegation

Every building with a water system needs someone responsible for managing legionella risk. ACoP L8 calls this the "responsible person" — but the term creates confusion because it overlaps with "duty holder," "competent person," and the everyday meaning of being responsible. These are distinct roles with different legal implications.

Here is who holds what obligation, how liability flows, and what to do if you are the person who ends up responsible.

The three roles in ACoP L8

ACoP L8 defines a hierarchy of responsibility for legionella control:

Duty holder

The person or organisation with overall legal responsibility. This is determined by the law, not by choice:

Situation	Who is the duty holder
Employer with premises	The employer
Landlord renting out property	The landlord (or management company if contractually responsible)
Building owner (non-domestic, non-employer)	The person in control of the premises
Shared building (multiple tenants)	Each employer for their area; the building owner/manager for common areas and shared systems

You cannot transfer duty holder status. A landlord who hires a managing agent remains the duty holder unless the management agreement explicitly assigns health and safety responsibilities — and even then, the landlord retains residual duties.

Responsible person

The individual appointed by the duty holder to take day-to-day management of legionella risk. HSE guidance states this person must have "sufficient authority, competence and knowledge of the installation" to manage the scheme.

For a landlord with a small portfolio, the duty holder and responsible person are typically the same person. For a care home, school, or commercial building, these roles are usually separated — the duty holder might be the board or owner, while a facilities manager acts as the responsible person.

Competent person

Someone with the skills, knowledge, and experience to help the duty holder assess and manage legionella risk. This might be the responsible person (if they have sufficient technical knowledge) or an external specialist engaged to conduct risk assessments and advise on control measures.

ACoP L8 does not require formal qualifications. "Competence" is defined by practical knowledge of water systems, legionella risk factors, and control measures — not by certificates or memberships. Industry bodies offer training and accreditation, but these are voluntary, not legally required.

What the responsible person must actually do

The responsible person's duties under ACoP L8 break down into five areas:

1. Ensure a risk assessment exists and stays current

A written, property-specific legionella risk assessment must be in place
It must be reviewed at least every two years, or sooner when the water system changes, building use changes, or monitoring reveals problems
See our guide to risk assessment review frequency

2. Implement and manage the written scheme of control

Document all control measures, monitoring schedules, and corrective action procedures
Ensure the scheme reflects the current risk assessment
See our written scheme of control guide

3. Ensure monitoring is carried out and recorded

The responsible person does not have to perform every check personally, but must ensure they happen:

Task	Frequency	What to record
Hot water outlet temperatures	Monthly	Reading, date, outlet location, who checked
Cold water outlet temperatures	Monthly	Reading, date, outlet location, who checked
Flushing of infrequent outlets	Weekly (outlets unused 7+ days)	Date, outlet, duration, who flushed
Showerhead descaling	Quarterly	Date, which showerheads, who cleaned
Cold water tank inspection	Annual	Condition, lid integrity, insulation, temperature

4. Act on non-compliant findings

When monitoring reveals a problem — a temperature out of range, a missed flush, visible contamination — the responsible person must:

Investigate the cause
Implement corrective action
Record what was found and what was done
Review whether the risk assessment or written scheme needs updating

5. Keep records accessible

HSE guidance on record-keeping specifies that monitoring records must be retained for at least five years. Risk assessments and written schemes must be kept for at least two years after they cease being current. These records must be accessible to inspectors on request.

How liability works

If a legionella incident occurs (an outbreak, a case of Legionnaires' disease, or an HSE investigation), liability flows through the hierarchy:

The duty holder is always liable. You cannot delegate away legal responsibility by appointing a responsible person. If the responsible person fails to carry out their duties, the duty holder is still legally accountable.

The responsible person may also be liable if they were personally negligent — for example, if they knew monitoring was not being done and took no action.

Prosecution can be personal. Under the Health and Safety at Work etc. Act 1974, individuals (not just organisations) can be prosecuted. Directors and managers who consent to or are negligent about health and safety failures can face personal criminal liability.

Practical implications for landlords:

Hiring a water treatment company to do a risk assessment does not transfer your duty holder obligations
A managing agent doing day-to-day management does not remove your legal responsibility unless explicitly contracted
Having a "legionella certificate" (which does not officially exist) does not protect you — ongoing compliance evidence does

Delegation: when and how

For a single residential property, delegation is unnecessary — the landlord is both duty holder and responsible person.

For multi-property portfolios or larger buildings, delegation becomes practical:

What you can delegate:

Day-to-day monitoring tasks (temperature checks, flushing)
Record-keeping administration
Arranging specialist risk assessments

What you cannot delegate:

Overall legal responsibility (duty holder status)
The obligation to ensure the system works

How to delegate effectively:

Put it in writing. Document who is responsible for what, with explicit task lists — not vague "manage legionella compliance"
Verify competence. The person you delegate to must understand water systems, legionella risk factors, and the specific system they are managing
Check the work. Review monitoring records periodically. Delegation without oversight is negligence
Name a deputy. ACoP L8 expects a backup when the responsible person is absent (holiday, illness)

When to appoint an external specialist

Self-management is appropriate for simple systems. Engage an external competent person when:

The building has a cooling tower, evaporative condenser, or spa pool
The water system serves more than approximately 50 outlets
There is a large cold water storage tank (300+ litres)
The building houses vulnerable occupants (care home, hospital, nursery)
Monitoring has revealed persistent temperature failures or positive legionella samples
You lack the technical knowledge to assess a complex system

For residential landlords with standard domestic systems (combi boiler or stored cylinder), HSE confirms self-assessment is appropriate if you are competent. See our guide on doing your own risk assessment.

Making the role manageable

The responsible person role is straightforward for simple buildings but becomes burdensome as portfolio size or system complexity grows. The recurring challenge is not the technical knowledge — it is the administrative consistency of monthly checks, weekly flushing, and quarterly cleaning across multiple properties, tracked over years.

LegioLog's Risk Assessment Template Generator creates building-specific assessments that document the responsible person and their duties. The Flushing Schedule Calculator generates a monitoring timetable based on your outlet inventory.

For the full regulatory context, see our ACoP L8 and HSG274 guide.

This guide covers the responsible person role under ACoP L8 for England, Wales, and Scotland. This is general compliance guidance, not legal or professional advice — for site-specific responsibilities, consult a competent person as defined by ACoP L8.