Who is responsible for arranging a Legionella Risk Assessment?

Responsibility for arranging a Legionella Risk Assessment rests with the duty holder who controls the premises, water system or related work activities. That person or organisation must ensure that a suitable assessment is completed by someone with the necessary competence, then act on its findings. They may appoint a specialist consultant to carry out the assessment, but appointing a contractor does not transfer the underlying legal responsibility.

The appropriate duty holder varies according to the property and contractual arrangements. It may be:

• an employer or business occupying its own premises;
• a building owner or landlord;
• a facilities management company or managing agent acting under delegated responsibilities;
• a housing provider or organisation responsible for rented accommodation; or
• a principal contractor or other organisation controlling temporary or construction-related water systems.

Ownership alone does not always determine who should arrange the assessment. The key question is who has sufficient control over the premises, water services and management arrangements to identify and control the risk. A lease, service contract or facilities agreement may allocate particular tasks to another party, so responsibilities should be defined in writing rather than assumed.

In a multi-occupancy building, more than one organisation may have duties. For example, a landlord may control central plant and communal supplies, while individual tenants control water systems within their own units. The parties should establish how the systems connect, which areas each party manages, who commissions the assessment and how shared risks are communicated. Separate assessments may be appropriate where systems, uses or control arrangements differ, but they should be coordinated where risks overlap.

Employers should consider Legionella as part of their health and safety arrangements where work activities or water systems could expose employees or others to the bacteria. The assessment should address relevant requirements under the Control of Substances Hazardous to Health Regulations 2002 (COSHH), together with the principles in the Health and Safety Executive’s Legionnaires’ disease: The control of legionella bacteria in water systems (L8) and the associated technical guidance in HSG274.

A competent assessor should be selected based on relevant knowledge, practical experience and the ability to assess the particular type of premises and water system. Competence is not established simply by holding a certificate or completing a short course. The appointed person should understand the system being examined, recognise conditions that could encourage Legionella growth and provide findings that the duty holder can use to manage the risk.

When arranging the assessment, the duty holder should give the assessor accurate information about:

• the use and occupancy of the building;
• the design and operation of hot and cold water systems;
• stored water, outlets, showers, tanks, calorifiers and other relevant equipment;
• infrequently used outlets, dead legs, redundant pipework and areas with low flow;
• vulnerable occupants or people who may be exposed through work activities;
• previous monitoring, maintenance, sampling, incidents and remedial work; and
• the division of responsibilities between owners, occupiers, contractors and managing agents.

The completed assessment should identify hazards, evaluate the likelihood of exposure, describe existing controls and set out further actions where controls are inadequate. It should also identify the person responsible for each action and any monitoring or maintenance needed. A report that merely describes the plumbing without assessing risk or assigning practical control measures is unlikely to provide an adequate management basis.

Arranging the assessment is only the first step. The duty holder must review the findings, implement necessary remedial measures and maintain suitable control arrangements. This can include temperature control, regular flushing, cleaning and disinfection, removal of redundant pipework, maintenance of tanks and outlets, monitoring and record keeping. Any work should be proportionate to the assessed risk and coordinated with the people who operate or occupy the premises.

The assessment should be reviewed when there is a significant change to the building, water system, use, occupancy or management responsibilities. It should also be reconsidered when monitoring identifies an issue, remedial works alter the system, or an incident raises concerns about existing controls. A named responsible person should be able to demonstrate that the assessment remains relevant and that identified actions are being managed.

A specialist water hygiene company can carry out the assessment and provide technical recommendations, but the client should confirm the scope, receive the report and retain responsibility for decisions within its control. Clear written arrangements between the duty holder and any appointed assessor help prevent gaps in responsibility, particularly where a building has several owners, tenants or maintenance providers.