Legionella Risk Assessment: Legal Requirements for UK Landlords and Businesses
Legionella Risk Assessment: Legal Requirements for UK Landlords and Businesses
Legionnaires' disease is a potentially fatal form of pneumonia caused by Legionella bacteria. Property owners and employers have a legal duty to assess and control the risk.
What Is Legionella?
Legionella is a bacteria found naturally in water sources. It becomes dangerous when it grows in man-made water systems and is inhaled through water droplets (aerosols).
Conditions for Growth
Legionella thrives when:
- Water temperature is 20-45°C
- Water is stagnant (stored or recirculated)
- There is sediment, scale, or biofilm for nutrients
- Water systems have complex pipework with dead legs
Who Needs a Legionella Risk Assessment?
Employers
Under the Health and Safety at Work Act 1974 and Control of Substances Hazardous to Health (COSHH) Regulations, employers must assess risks from:
- Hot and cold water systems
- Cooling towers and evaporative condensers
- Spa pools and hot tubs
- Humidifiers and water features
Landlords
Landlords must assess legionella risk for:
- Residential rental properties
- Commercial premises
- Holiday lets
- HMOs (Houses in Multiple Occupation)
Duty Holders
Anyone in control of premises, including:
- Facilities managers
- Building owners
- Letting agents (if responsible)
Legal Framework
Key legislation includes:
| Legislation | Requirement | |-------------|-------------| | Health and Safety at Work Act 1974 | General duty to protect health | | COSHH Regulations 2002 | Assess and control hazardous substances | | Management Regulations 1999 | Risk assessment requirement | | Approved Code of Practice L8 (ACOP L8) | Practical guidance on compliance |
What Does a Legionella Assessment Cover?
1. Identify Potential Risks
- Water storage tanks (cold water storage cisterns)
- Hot water cylinders and calorifiers
- Pipework design (dead legs, little-used outlets)
- Shower heads and hoses
- Cooling systems
- Water features
2. Assess Who Is at Risk
- Employees
- Tenants and residents
- Visitors
- Vulnerable groups (elderly, immunocompromised)
3. Evaluate Controls
- Temperature monitoring
- System flushing
- Cleaning and disinfection
- Biocide treatment
- System design modifications
4. Record Findings
Document:
- The system assessed
- Risks identified
- Control measures in place
- Additional actions needed
- Review schedule
Temperature Control
The primary control method is temperature:
| Temperature | Effect on Legionella | |-------------|---------------------| | Below 20°C | Dormant (no growth) | | 20-45°C | Active growth zone | | 50°C | Killed in 2-3 hours | | 60°C | Killed in 32 minutes | | 70°C+ | Killed instantly |
Hot Water Requirements
- Store at 60°C minimum
- Distribute at 50°C+ at outlets
- Warning: Scalding risk - install TMVs (thermostatic mixer valves) where vulnerable people use outlets
Cold Water Requirements
- Store and distribute below 20°C
Control Measures
For Simple Systems (Domestic Properties)
- Set hot water cylinder to 60°C
- Run taps and showers weekly (especially in unused rooms)
- Clean shower heads quarterly
- Inspect cold water tanks annually
- Flush little-used outlets regularly
For Complex Systems (Commercial Buildings)
- Written scheme of control
- Temperature monitoring programme
- Regular system flushing
- Quarterly cleaning of shower heads
- Annual tank inspection and cleaning
- Biocide dosing (where appropriate)
- Monthly dip slide sampling
- Annual legionella testing
When to Use a Specialist
Consider professional assessment for:
- Large or complex buildings
- Cooling towers and evaporative condensers
- Healthcare premises
- Hotels and leisure centres
- Buildings with vulnerable occupants
Look for assessors who are:
- Members of the Legionella Control Association (LCA)
- Qualified to WMSoc or similar standards
- Experienced in your building type
Penalties for Non-Compliance
Failure to manage legionella risk can result in:
- Unlimited fines
- Imprisonment for individuals
- Enforcement notices
- Corporate manslaughter charges in fatal cases
Case Study
In 2023, a UK company was fined £1.8 million after a worker died from Legionnaires' disease contracted from a cooling tower. The company had failed to maintain adequate controls.
How Often to Review
Review your assessment:
- Annually as minimum
- When water systems change
- When building use changes
- After refurbishment or extension
- If legionella is detected
- After cases or outbreaks
Simple Landlord Checklist
For residential rental properties:
- [ ] Check hot water temperature (60°C at cylinder)
- [ ] Inspect cold water tank for debris
- [ ] Ensure tank has tight-fitting lid
- [ ] Run all taps and showers weekly
- [ ] Clean shower heads quarterly
- [ ] Flush system after void periods
- [ ] Record actions taken
- [ ] Review annually
Summary
Legionella risk assessments are a legal requirement, but for most properties, simple controls are sufficient. The key is maintaining appropriate temperatures and preventing water stagnation.