Need to assess Legionella risk?
Protect your tenants and comply with your legal duty to control water safety.
Complete guide to Legionella risk assessment and control measures for landlords, covering legal obligations and practical steps.
Understanding Legionella
Learn about the bacteria and your legal duty
What is Legionella?
Understand the risk and your legal obligations.
Legionella Bacteria
Legionella is a bacteria that can cause Legionnaires' disease, a potentially fatal form of pneumonia. It grows in water systems and spreads through water droplets that people breathe in.
Where Legionella Grows
- Temperature range: 20-45°C (ideal growth conditions)
- Water systems: Hot and cold water tanks, pipes, showers, taps
- Stagnant water: Little-used outlets, dead legs in pipework
- Biofilm and scale: Provides nutrients for bacteria
How People Get Infected
- Breathing in small water droplets (aerosols) containing bacteria
- Common sources: showers, taps, cooling systems
- NOT spread person-to-person or by drinking water
Your Legal Duty
Under the Health and Safety at Work Act 1974 and Control of Substances Hazardous to Health (COSHH) Regulations, landlords must:
- Identify and assess sources of risk
- Manage any risks
- Prevent or control any risks
- Keep and maintain correct records
- Carry out checks to ensure measures remain effective
⚠️ Risk Level in Domestic Properties:
The risk is generally LOW in domestic properties with normal use. However, you still have a legal duty to assess and control risks. The risk increases in vacant properties and those with complex water systems.
Templates & Downloads
Legionella Risk Assessment Template
Complete template for conducting risk assessments
Conducting Risk Assessment
Assess your property for Legionella risks
Conduct Legionella Risk Assessment
Systematic assessment of water systems.
Risk Assessment Steps
1. Identify Water Systems
Map all water systems in the property:
- Cold water storage tanks (location, size, condition)
- Hot water cylinders (location, size, temperature)
- All taps and outlets (bathrooms, kitchens, outside taps)
- Showers (including hoses and heads)
- Any other water outlets
2. Identify Risk Factors
Check for conditions that increase risk:
- Water temperature: Is water stored or distributed at 20-45°C?
- Stagnation: Are there little-used outlets or dead legs?
- Water storage: Are tanks clean and properly covered?
- Scale and corrosion: Is there limescale or rust in system?
- Biofilm: Is there slime or discolouration?
3. Check Water Temperatures
Measure and record temperatures:
- Hot water storage: Should be at least 60°C
- Hot water at tap: Should be at least 50°C within 1 minute
- Cold water storage: Should be below 20°C
- Cold water at tap: Should be below 20°C
4. Inspect Water Tanks
If property has water tanks, check:
- Tank has tight-fitting lid
- Tank is insulated (cold tank) or lagged (hot cylinder)
- No debris or contamination inside
- Overflow pipe has insect screen
- Tank is clean (no sediment or biofilm)
5. Identify Dead Legs
Dead legs are sections of pipe with little or no water flow:
- Capped-off pipes from previous alterations
- Long pipe runs to little-used outlets
- Pipes to removed fixtures
Action: Remove dead legs or flush regularly
💡 Simple Risk Assessment:
For most domestic properties, if hot water is stored at 60°C, distributed at 50°C+, cold water is below 20°C, and all outlets are used regularly, the risk is LOW and simple control measures are sufficient.
Checklist
- ✓Identify all water outlets and storage
- ✓Check hot water storage temperature (60°C)
- ✓Check hot water tap temperature (50°C)
- ✓Check cold water temperature (below 20°C)
- ✓Inspect cold water tank (if present)
- ✓Check tank has tight-fitting lid
- ✓Verify tank insulation
- ✓Identify any dead legs in pipework
- ✓Check for little-used outlets
- ✓Inspect shower heads and hoses
- ✓Document all findings
- ✓Create action plan for any issues
Implementing Control Measures
Put controls in place to manage risks
Implement Control Measures
Practical steps to control Legionella risk.
Essential Control Measures
Temperature Control
- Hot water storage: Maintain at 60°C minimum
- Hot water distribution: Deliver at 50°C minimum at taps
- Cold water: Keep below 20°C (insulate tanks and pipes)
- Check regularly: Test temperatures monthly
Prevent Stagnation
- Flush little-used outlets: Run for 2 minutes weekly
- Remove dead legs: Cap off at nearest junction or flush regularly
- Vacant properties: Flush all outlets before new tenancy
- Guest bathrooms: Ensure used or flushed regularly
Maintain Water Systems
- Service hot water cylinder: Annually by qualified engineer
- Clean cold water tanks: Every 2-5 years (or if contaminated)
- Descale taps and showers: Quarterly or as needed
- Replace shower hoses: Every 1-2 years
- Clean shower heads: Quarterly - remove, dismantle, descale
Water Tank Maintenance
- Ensure tight-fitting lid (prevent contamination)
- Check insulation is adequate
- Inspect for debris, sediment, or biofilm
- Verify overflow has insect screen
- Clean if any contamination found
✅ Simple Weekly Routine:
- Run all little-used taps for 2 minutes
- Run all showers for 2 minutes
- Check water runs hot (50°C+) and cold (below 20°C)
- Record in logbook
Special Considerations for Vacant Properties
Higher risk when properties are empty.
Managing Vacant Properties
Properties left vacant for more than a week have increased Legionella risk due to water stagnation.
Before Tenancy Ends
- Note date property will be vacant
- Plan flushing regime if void period expected
- Consider draining system if vacant for extended period
During Void Period
- Weekly flushing: Run all taps and showers for 2 minutes
- Check temperatures: Ensure hot water still reaching 50°C+
- Keep heating on: Low setting to prevent pipes freezing
- Record all flushing: Keep log of dates and actions
Before New Tenancy
Before new tenants move in, conduct thorough flushing:
- Flush all outlets: Run each tap and shower for at least 2 minutes
- Clean shower heads: Remove, dismantle, descale, disinfect
- Check water temperatures: Hot at 50°C+, cold below 20°C
- Inspect for issues: Check for leaks, discolouration, unusual smells
- Document: Record date and actions taken
⚠️ Extended Void Periods:
If property will be vacant for more than 4 weeks, consider draining the system completely or arranging weekly professional flushing. Consult a water treatment specialist for properties vacant over 3 months.
Templates & Downloads
Vacant Property Water System Checklist
Checklist for managing water systems in empty properties
Record Keeping & Review
Maintain compliant records
Keep Proper Records
Documentation is a legal requirement.
What Records to Keep
Risk Assessment Records
- Date of assessment
- Who conducted it
- Water systems identified
- Risks identified
- Control measures implemented
- Review date
Monitoring Records
- Temperature checks (monthly minimum)
- Flushing of little-used outlets (weekly)
- Shower head cleaning (quarterly)
- Tank inspections (annually or as needed)
- Any remedial work carried out
Maintenance Records
- Hot water cylinder servicing (annually)
- Tank cleaning (every 2-5 years)
- Shower hose replacements
- Any repairs or modifications to water system
- Vacant property flushing logs
How Long to Keep Records
- Risk assessments: Keep current assessment plus previous 2 years
- Monitoring logs: Keep for at least 2 years
- Maintenance records: Keep for at least 5 years
💡 Simple Record System:
Use a simple logbook or spreadsheet. Record: Date, Action taken (e.g., "Flushed all outlets"), Temperatures checked, Any issues found, Who did it. Takes 2 minutes per check.
Review Your Risk Assessment
You must review your risk assessment:
- Every 2 years minimum
- When changes occur: New water system, modifications, change of use
- After incidents: Any water quality issues, tenant reports
- If control measures fail: Temperature out of range, contamination found
Templates & Downloads
Water Temperature Log Sheet
Template for recording water temperatures
Legionella Monitoring Logbook
Complete logbook for all Legionella control activities
Frequently Asked Questions
Common questions about legionella risk management
What's Next?
You've completed the Legionella Risk Management. Here are some related resources to help you further.
Guidance only. Landlord Handbook provides practical information to help landlords understand their responsibilities. It is not legal or financial advice. Always check the latest GOV.UK guidance and seek professional advice where appropriate.