What happens if a commercial legionella risk assessment identifies control deficiencies?

A finding of control deficiencies does not automatically mean that a workplace must close, but it does mean the organisation’s existing arrangements cannot be treated as fully reliable until the identified issues have been addressed. The responsible person should understand the nature of each deficiency, assess the associated exposure, introduce proportionate interim precautions where necessary, and retain evidence that the corrective response has been completed and verified.

The first step is to interpret the finding correctly. A deficiency may relate to the condition or design of a water system, inadequate temperature control, poor asset information, an ineffective written scheme, gaps in monitoring, unclear responsibilities, or incomplete records. These findings do not all carry the same significance. A missing record may require a different response from a failed control measure affecting outlets used by vulnerable people. The assessment should therefore be read as a set of prioritised findings rather than as a simple pass-or-fail result.

Where the assessor identifies a credible and immediate exposure, the responsible person may need to take interim measures before permanent work is completed. Depending on the circumstances, this could include restricting access to an affected outlet, suspending use of part of a system, providing alternative facilities, increasing supervision, or obtaining specialist technical advice. Any temporary measure should be recorded with its owner, start date, review point and intended end condition. It should not become a substitute for resolving the underlying defect.

Each finding should be converted into an action plan. A useful plan normally records:

• the deficiency and the part of the system or management process affected;
• the reason it matters, including the relevant exposure or failure of control;
• the corrective action required and whether it is temporary or permanent;
• the person or organisation responsible for completing it;
• the target date, dependencies and any access or shutdown requirements;
• the evidence needed to demonstrate completion; and
• how the action will be checked for effectiveness.

This approach helps distinguish actions that can be completed by the site team from those requiring a competent water hygiene contractor, specialist engineer or laboratory. It also makes it easier for facilities managers, landlords, occupiers and contractors to understand who is accountable when responsibility for the water system is shared.

Some deficiencies can be corrected through management changes, such as clarifying responsibility, improving the written scheme, updating asset registers or revising monitoring instructions. Others may require physical intervention, including cleaning, disinfection, component replacement, removal of redundant pipework, correction of low-use outlets or changes to the system’s operation. The appropriate remedy depends on the cause of the deficiency; treating a symptom without correcting that cause can leave the risk in place.

Where water sampling or other verification has identified an adverse result, the result should be considered alongside the system inspection and management information. A single sample may indicate a localised issue, but it should not be used in isolation to decide that an entire building is safe or unsafe. The response may involve checking sampling technique and location, reviewing recent system events, examining trends, and carrying out further investigation or verification when the corrective work has been completed.

Records are part of the response, not an administrative afterthought. The organisation should retain the assessment, action plan, interim-control records, work reports, monitoring results, laboratory reports where relevant, and evidence of management review. Records should show what was found, what changed, when it changed, who authorised it and how effectiveness was confirmed. This creates an auditable link between the assessment and the organisation’s ongoing control arrangements.

The written scheme and associated risk information may need updating if the deficiencies reveal a change in the system, building use, occupancy, responsible personnel or control method. Staff and contractors whose duties are affected should be informed and trained where necessary. For example, revised temperature checks or flushing instructions are only useful if the people carrying them out understand the procedure, have suitable equipment and know what to do when a result falls outside the defined control range.

Closure should be based on evidence rather than the passage of time. Depending on the finding, evidence may include completed works documentation, commissioning information, updated procedures, satisfactory monitoring records, follow-up inspection or appropriately selected verification samples. If an action cannot yet be completed, the residual risk and interim arrangements should be reviewed and accepted by the responsible person at an appropriate management level.

Once significant deficiencies have been addressed, a follow-up review should confirm that the controls now operate as intended and that no new risks were introduced by the changes. The next routine review should also consider whether the findings indicate a broader weakness in the organisation’s water safety management, rather than an isolated fault. For businesses managing complex or multi-site premises, this can be particularly important because a recurring issue may require a common procedure, clearer governance or a wider programme of remedial work.

Blue Fish Water Management Ltd can support organisations with the technical interpretation of findings, compliance reviews, water testing, monitoring arrangements and remedial recommendations. The responsible person remains accountable for ensuring that the agreed controls are implemented, maintained and reviewed.