Who is responsible for arranging a Legionnaires disease risk assessment?

The duty to arrange a Legionnaires’ disease risk assessment sits with the person or organisation responsible for managing the relevant premises, workplace or water system. They must ensure that the assessment is suitable, sufficient and completed by someone with the necessary competence, whether that is an employee or an external specialist.

Under the Health and Safety at Work etc. Act and the Control of Substances Hazardous to Health Regulations, the duty holder must assess and control risks from exposure to Legionella bacteria where people could inhale contaminated water droplets or aerosols. The duty may apply to:

• an employer controlling a workplace and its water systems;
• a building owner or landlord responsible for water services;
• a facilities or property manager acting on behalf of an owner;
• an organisation operating premises such as a care setting, hotel, school or leisure facility; or
• another person who has sufficient control over the premises, plant or water-system maintenance.

Responsibility can be shared. For example, a building owner may control the incoming water services while an occupier manages day-to-day operations. A managing agent, maintenance contractor or specialist assessor may carry out particular tasks, but the parties should define their respective duties clearly. A service contract does not automatically remove the legal obligations of the person who retains control.

Where more than one organisation has responsibilities, they should cooperate and communicate. The arrangements should identify who will:

• arrange the initial and subsequent assessments;
• provide access to plant rooms, tanks, outlets and other relevant areas;
• maintain records such as schematic drawings, monitoring results and maintenance logs;
• manage temperature control, cleaning, disinfection and other precautions;
• respond to defects or evidence of elevated risk; and
• review the assessment after changes to the system, occupancy or use of the building.

The person arranging the assessment must take reasonable steps to select a competent assessor. Competence involves appropriate knowledge, training and practical experience in Legionella risk management and the type of water system being examined. A certificate or qualification alone does not demonstrate competence. The duty holder should consider the assessor’s relevant experience, proposed methodology, understanding of current guidance and ability to produce clear, site-specific findings.

An assessment should not be treated as a generic document prepared without inspecting the premises. The assessor normally needs to understand the system from the incoming supply through storage, distribution, outlets and associated equipment. This may include reviewing design information, interviewing relevant staff, examining accessible components and identifying conditions that could support bacterial growth or produce aerosols.

The duty holder also needs to give the assessor accurate information and suitable access. Relevant information may include water-system drawings, asset registers, previous monitoring results, maintenance records, records of temperature checks, details of vulnerable occupants and any history of remedial work. Missing information should be recorded and resolved rather than assumed away.

Arranging the assessment is only the first part of the responsibility. The duty holder must consider the findings, establish a written control scheme where required, appoint people to carry out monitoring and maintenance, and ensure that significant recommendations are addressed. If the assessment identifies an immediate or substantial concern, delaying action while waiting for a routine review may leave the risk inadequately controlled.

In smaller organisations, the duty holder may be able to complete the assessment internally if the person undertaking it has sufficient competence and independence for the task. Where the system is complex, poorly documented, shared between occupiers or associated with vulnerable people, using a suitably experienced specialist can provide a more robust assessment. Blue Fish Water Management Ltd provides Legionella risk assessments, water testing, compliance audits and related water hygiene support for commercial, industrial and domestic clients across the UK.