How to Carry Out a Legionella Risk Assessment – Step-by-Step
Knowing how to carry out a Legionella risk assessment is a legal requirement for anyone responsible for premises with a water system. This step-by-step guide explains how competent persons assess the risk of Legionella bacteria in domestic, commercial and healthcare settings.
Step 1: How to Carry Out a Legionella Risk Assessment Legally
The dutyholder (employer, landlord, or building owner) must ensure a suitable and sufficient Legionella risk assessment is completed. This is a requirement under:
- Health & Safety at Work Act 1974
- COSHH Regulations 2002
- HSE’s Approved Code of Practice L8
If you’re the designated duty holder or responsible person for your premises, it’s essential to understand your legal obligations.
See our guide on what the law says about Legionella risk assessments and the role of the responsible person for Legionella control for more detailed support.
Step 2: Identify All Water Systems
All hot and cold water systems must be assessed, including:
- Taps, showers and sinks
- Water heaters and calorifiers
- Storage tanks and pipework
- Outdoor taps, fountains, and decorative features
- Any infrequently used outlets
Step 3: Assess the Risk Factors
A competent assessor will consider:
- Water temperatures (risk if 20–45°C)
- Stagnation or dead legs in pipework
- Scale, corrosion, or sediment
- Presence of vulnerable users (e.g. elderly or immunocompromised)
- Complexity and age of the system
Step 4: Record Findings
The assessor documents:
- Risk levels for each area
- Any remedial actions needed
- Schematic drawing of the system
- Photos, measurements and system notes
Step 5: Create a Written Scheme of Control
If risks are identified, you must create a written plan to manage them. This includes:
- Temperature control strategy
- Regular flushing schedules
- Maintenance checks
- Responsible person assigned
Step 6: Review the Assessment
You must review the assessment:
- Every 2 years
- When the system changes
- After an incident or outbreak
- If vulnerable people occupy the building
Need help carrying out a Legionella risk assessment? Contact us today for expert support across South Yorkshire.
