How often should legionella inspections be carried out?
The interval between legionella inspections should be set by the site-specific control scheme, rather than by a universal legal timetable. A competent person should determine how frequently the system needs to be inspected by considering the complexity of the water services, the people exposed, the condition of the plant, previous monitoring results and the effectiveness of existing controls.
Inspection frequency should reflect risk. A simple, well-maintained system with stable control results may need less frequent formal inspection than a large or complex system with storage tanks, extensive distribution pipework, showers, spa facilities, cooling systems or areas used by people who may be more susceptible to infection. Systems with a history of poor temperature control, stagnation, contamination or remedial work should be subject to closer scrutiny until control has been demonstrated.
A legionella inspection is not a substitute for routine control checks. The written scheme should identify the checks needed between formal inspections, such as temperature monitoring, examination of tanks and cylinders, review of outlets that are rarely used, and confirmation that flushing or other control measures have been completed. The required frequency for each activity should be documented and followed by suitably trained personnel.
An additional inspection is needed when circumstances change. This may include:
- alterations to the water system, plant, building use or occupancy;
- the installation, removal or replacement of water outlets, tanks, heaters or pipework;
- prolonged periods of low occupancy or system shutdown;
- failures in temperature control, disinfection, monitoring or maintenance;
- evidence of stagnation, contamination or unusual water-quality results; or
- a suspected or confirmed case of legionnaires’ disease associated with the premises.
After a significant change, the inspection should confirm that the risk assessment, schematic diagrams, written control scheme and monitoring arrangements still describe the system accurately. It should also identify whether remedial work, additional sampling or a revised control measure is required.
Do not confuse an inspection with a risk-assessment review. An inspection examines the physical system and the way controls are being applied. A risk-assessment review considers whether the hazards, responsible persons and control arrangements remain accurate and adequate. They may be carried out together, but they serve different purposes. Routine monitoring and water sampling are separate activities with their own risk-based schedules.
Inspection findings should be recorded clearly, including the areas examined, defects identified, readings or other relevant evidence, corrective actions, responsible persons and completion dates. Records help demonstrate that the system is being managed consistently and allow trends to be identified before they become a significant control failure.
Where the required interval is unclear, the responsible person should obtain advice from a competent water hygiene professional rather than rely on a generic calendar reminder. The appropriate schedule is the one supported by the risk assessment and written scheme, with the flexibility to increase inspection frequency when conditions or results indicate a higher level of risk.
The appropriate interval depends not only on the level of risk, but also on what each inspection is designed to examine. A useful inspection should provide evidence about the condition and operation of the whole water system, rather than consist of a brief visual check of accessible equipment.
- water heaters, storage vessels, thermostatic mixing valves and associated pipework;
- insulation, lids, access points, temperature controls and signs of corrosion or contamination;
- outlets, little-used sections and any features that could encourage stagnation; and
- the records and procedures showing that identified controls are being applied.
If parts of the system cannot be accessed or records are incomplete, the inspection report should state the limitation and explain whether further investigation is needed. This helps the responsible person judge whether the existing inspection interval remains appropriate, instead of treating a scheduled visit as proof that every relevant risk has been checked.
Need a risk-based legionella inspection schedule?
If your current inspection interval is not clearly supported by your risk assessment and written scheme, speak to Blue Fish Water Management Ltd about developing a risk-based inspection schedule for your site.