Legionella Risk Management in Primary Care: A Practical Guide for GP and Dental Practices

Legionella pneumophila causes Legionnaires' disease, a potentially fatal form of pneumonia. The bacteria thrive in water systems where temperatures are between 20°C and 45°C, where nutrients are present, and where water is allowed to stagnate. GP surgeries and dental practices are particularly susceptible: they have complex water systems, multiple outlets, varying usage patterns, and a patient population that includes clinically vulnerable people for whom the consequences of infection are far more severe than for healthy adults.

CQC inspectors consistently identify legionella risk management as one of the top three compliance failures in primary care settings. The legal framework is not ambiguous: the Health and Safety at Work Act 1974, the Management of Health and Safety at Work Regulations 1999, and the HSE's Approved Code of Practice L8 (Legionella) place a clear duty on every employer to assess and manage legionella risk in their water systems.

HSE ACoP L8 requires a written Legionella risk assessment covering all water systems, a water safety management plan, a named responsible person, and ongoing monitoring records. Inspectors treat gaps in temperature monitoring logs as direct evidence of active risk. A Legionella-positive test result in a healthcare setting triggers a mandatory RIDDOR report to the HSE.

What Does a Legionella Risk Assessment for a GP Surgery Actually Cover?

A legionella risk assessment carried out under ACoP L8 is not a paper exercise. It requires a qualified water hygiene specialist to attend site, map the water system, and identify risk factors. The assessment must cover:

• A schematic drawing of the entire water system — hot and cold supplies, storage tanks, calorifiers, and all outlets including infrequently used ones
• Water temperature survey at sentinel points — confirming cold water is consistently below 20°C and hot water above 50°C at the outlet
• Identification of dead legs and low-use outlets — sections of pipework or outlets that rarely flush, creating stagnation risk
• Assessment of any stored water — cold water storage tanks and calorifiers are the highest-risk components; their condition, insulation, and temperature management must be assessed
• Risk rating for each identified hazard — with a recommended control measure and a monitoring frequency for each

What Monitoring Is Required After the Assessment?

The assessment tells you where the risks are. The monitoring programme controls them. For most GP surgeries, the minimum monitoring programme under ACoP L8 covers: monthly temperature checks at sentinel hot and cold outlets, with results logged and dated; quarterly inspection of the cold water storage tank where one is present; annual review of the full risk assessment; and temperature checks of any infrequently used outlets before clinical use. For dental practices, dental unit waterlines require a separate management protocol and regular microbiological testing.

CQC inspectors ask to see the log. The most common finding is not a missing risk assessment — it is a log with gaps. A three-month gap in temperature monitoring records tells an inspector that the control programme was not being maintained, regardless of what the risk assessment says. The paper record is the only evidence of what was actually done.

What Are Dental Unit Waterlines and Why Do They Matter?

Dental unit waterlines (DUWLs) present a specific and often underestimated legionella and biofilm risk. The narrow-bore tubing in dental units, combined with relatively low flow rates and intermittent use, creates ideal conditions for biofilm formation. British Dental Journal research has consistently identified DUWL management as one of the most common compliance failures in dental practices. The water that travels through these lines can enter the patient's mouth during treatment.

Dental practices must have a DUWL management policy that covers daily flushing protocols, regular disinfection, and periodic microbiological testing of unit water. The policy must align with the manufacturer's guidance for each dental chair. Evidence of the flushing and disinfection programme must be maintained in a log that is accessible during inspection. Practices that treat dental unit waterlines as a separate category from the general water system — which they are — need a separate, documented control programme for them.

When Does a Legionella Risk Assessment Need to Be Repeated?

The risk assessment must be reviewed and updated when: any significant change is made to the water system or its use; occupancy patterns change significantly; the building undergoes refurbishment; a Legionella-positive sample is found; or a period of low or no occupancy has occurred. A building that has been partially empty — for example during a practice closure or a phased refurbishment — requires recommissioning of the water system under HTM 04-01 before normal clinical use resumes.

For a practice that has never had a Legionella risk assessment, or whose last assessment pre-dates any significant change to the building or patient list, commissioning a compliant assessment from a UKAS-accredited water hygiene specialist is the immediate first step. The assessment itself takes one site visit. The written report follows within five to ten working days. The monitoring programme that flows from it is ongoing — but it is far less disruptive than a CQC finding or a RIDDOR investigation.