What Happens During a Legionella Risk Assessment? A Step by Step Guide
If you have been told your business needs a Legionella Risk Assessment, the first question is usually simple. What actually happens on the day?
At The HSRA, we carry out Legionella Risk Assessments across a wide range of properties. Unlike fire safety, Legionella risk is not always visible, which makes the process slightly more technical, but just as important.
This guide explains exactly what happens during a Legionella Risk Assessment, so you know what to expect and how to prepare.
Step 1. Understanding Your Water System
Every assessment starts with understanding how water is used within your premises. The assessor will review the type of property, whether that is a dental practice, gym, office or HMO. They will also look at the layout, number of floors, how water is supplied and distributed, and who uses the building.
Legionella risk depends heavily on how water systems are used, not just how they are designed. This first step provides the foundation for the rest of the assessment.
Step 2. A Visual and Non Intrusive Inspection
A Legionella Risk Assessment is designed to be non intrusive and practical. It is based on visual inspection of accessible systems, temperature testing, and reviewing documentation available on the day. There is no dismantling of systems, no internal pipe inspections, and no laboratory testing unless arranged separately.
The focus is on identifying risk conditions and understanding how well they are being controlled.
Step 3. Identifying Your Water Systems
The assessor will identify and map out your water system. This includes hot and cold water systems, all outlets such as taps, showers and basins, as well as boilers, water heaters, and storage vessels. Any plant or equipment connected to the system will also be considered.
They will also look for higher risk features such as dead legs, redundant pipework, and complex systems with multiple outlets. Understanding your system is key to managing Legionella risk effectively.
Step 4. Inspecting Water Outlets
All accessible outlets will be reviewed as part of the inspection. This includes taps, showers, sinks, and any ancillary outlets such as those in staff kitchens or utility areas. The assessor will check their condition and look for signs of scale, sludge or corrosion.
Common issues include limescale build up, poorly maintained outlets, and outlets that are no longer in use but still connected to the system.
Step 5. Identifying Infrequently Used Outlets
One of the biggest risks for Legionella comes from stagnant water. The assessor will identify outlets that are rarely used, areas that are no longer in use, and rooms that may be locked or repurposed. Examples include spare bathrooms, isolated sinks, or seasonal areas.
When water sits unused, it creates ideal conditions for bacteria to grow, so these areas are always a key focus.
Step 6. Temperature Testing
Temperature control is one of the most important control measures. The assessor will carry out temperature checks to confirm that cold water is below 20 degrees and hot water reaches at least 50 degrees within a reasonable time. Multiple outlets are tested to ensure consistency.
If temperatures fall outside these ranges, it increases the risk of bacterial growth and will be highlighted in the report.
Step 7. Inspecting Plant and Equipment
Where applicable, the assessor will inspect plant and equipment connected to the water system. This may include boilers, hot water storage vessels, cold water tanks, and air conditioning units where relevant. The focus is on condition, accessibility, and evidence of maintenance.
A common issue is not faulty equipment, but a lack of servicing records or ongoing maintenance.
Step 8. Reviewing System Management
Legionella control is as much about management as it is about the system itself. The assessor will review who is responsible for managing Legionella risk, whether responsibilities are clearly defined, and whether day to day control measures are in place.
One of the most common gaps is the absence of a formally appointed responsible person. Without clear ownership, control measures are often inconsistent.
Step 9. Documentation Review
The assessor will review any existing documentation you have available. This includes previous Legionella Risk Assessments, temperature monitoring logs, flushing records, maintenance records, and staff training documentation.
They will also check for a schematic diagram of the system and a written scheme of control. If these are missing or incomplete, this will be recorded with clear recommendations.
Step 10. Identifying Control Measures and Gaps
At this stage, the assessor will identify what control measures are currently in place and where gaps exist. Common findings include no flushing regime for infrequently used outlets, lack of temperature monitoring, no written procedures, and poor maintenance.
These are often management issues rather than physical faults, but they are just as important when it comes to compliance.
Step 11. Risk Assessment and Findings
Each identified risk is assessed based on likelihood and potential impact. This allows risks to be prioritised and addressed in a structured way. Your report will outline the hazards identified, who may be at risk, the current controls in place, and the recommended actions.
This turns the assessment into a practical action plan rather than just a list of issues.
Step 12. Final Report and Recommendations
Following the visit, all findings are documented in a clear and structured report. This provides a full overview of your current level of compliance, along with practical steps to reduce risk and guidance on ongoing management.
Reports are typically issued within 48 hours once payment has been received.
Important. It Is Not a One Off Exercise
A Legionella Risk Assessment is not something you do once and forget about. It is a snapshot of your current risk and a framework for ongoing control. Tasks such as temperature monitoring, flushing outlets, and regular maintenance are essential to staying compliant.
Ongoing management is just as important as the initial assessment.
How to Prepare for Your Legionella Risk Assessment
Preparation will help the assessment run smoothly.
Make sure all water outlets are accessible, ensure plant rooms can be accessed, gather any existing documentation, and have a responsible person available on site.
If documentation is missing, it will simply be recorded with recommendations on what is required.
Need a Legionella Risk Assessment?
At The HSRA, we carry out Legionella Risk Assessments across the UK, including temperature testing and optional water sampling where required.
If you are unsure where you stand or need to get compliant quickly, get in touch with the team today.