How often should legionnaires inspections be carried out?

Legionnaires inspections should be carried out at the frequency identified in the site-specific control scheme, rather than to a universal timetable. The appropriate interval depends on the type and complexity of the water system, the likelihood of exposure to contaminated aerosols, the condition of the equipment, occupancy patterns and the effectiveness of existing controls. A competent person should set and justify the schedule through the legionella risk assessment.

Inspection is not the same as routine monitoring. A formal inspection considers whether the system remains correctly designed, operated and maintained, including storage tanks, calorifiers, pipework, outlets, thermostatic mixing valves and areas of low or no use. Routine monitoring may include temperature checks, flushing, dosing checks, cleaning observations or review of water quality results. These activities can take place at different intervals, as defined by the written scheme of control.

The inspection frequency should reflect the level of risk. More frequent attention may be appropriate where a system is large or complex, serves vulnerable people, contains areas prone to stagnation or operates with inadequate temperature control. Healthcare premises, care settings, residential accommodation, hotels, leisure facilities and industrial sites may each require different arrangements because their occupants, water systems and exposure risks are not the same. A simple system with stable controls may need a less intensive inspection programme, but this must still be supported by a documented assessment.

Additional inspections should be arranged when circumstances change. Relevant triggers include:

• alterations to the water system, plant, pipework or building layout;
• a change in building use, occupancy or vulnerable-person risk;
• extended periods of low use, closure or partial occupation;
• repeated temperature failures, control failures or maintenance problems;
• positive or abnormal legionella test results;
• an outbreak, suspected case or other incident involving possible exposure;
• evidence that flushing, cleaning, disinfection or other control measures are not being completed effectively; and
• changes to the responsible persons, contractors or written control arrangements.

Following a significant change or incident, the responsible person should not simply wait for the next planned visit. The risk assessment and control measures should be reviewed, and the system should be inspected to establish whether remedial action, further sampling or specialist advice is needed.

Legal compliance depends on managing the risk, not ticking off a standard inspection interval. Under UK health and safety duties, the person responsible for premises or water systems must assess and control risks from legionella, appoint suitable competent assistance where necessary, and maintain appropriate records. The HSE's Approved Code of Practice L8 and technical guidance in HSG274 provide the main framework used to determine suitable control arrangements. They do not replace the need for a site-specific decision about inspection frequency.

Every inspection should produce a clear record showing the date, systems and outlets examined, findings, measurements or test results where relevant, defects identified, actions required, responsible persons and completion dates. Reviewing these records helps identify recurring problems and provides evidence that the control scheme is being implemented. A pattern of missed checks or repeated failures is a reason to reconsider whether the inspection schedule remains suitable.

Where responsibilities are shared between a building owner, managing agent, facilities team and specialist contractor, the written arrangements should state who arranges each inspection and who acts on its findings. Blue Fish Water Management Ltd can provide risk-based legionella inspections, monitoring, testing and remedial advice to help organisations maintain a documented water safety programme.