What is Legionella?

Legionella bacteria occur naturally in water. They can multiply in water systems where conditions are favourable — typically between 20°C and 45°C — and cause Legionnaires' disease, a potentially fatal form of pneumonia, when contaminated water droplets are inhaled.

Your Legal Duty as a Landlord

Under the Health and Safety at Work Act 1974 and the Control of Substances Hazardous to Health Regulations 2002 (COSHH), landlords have a duty to assess and control the risk of Legionella in their rental properties. The HSE's Approved Code of Practice L8 and guidance document HSG274 set out how to comply.

This applies to all residential landlords, regardless of the size or type of property.

Conducting a Risk Assessment

A Legionella risk assessment should identify:

• Potential sources of risk (water tanks, cylinders, showers, infrequently used outlets)
• Whether conditions exist that encourage bacterial growth (stagnant water, temperatures between 20–45°C)
• Who may be at risk (tenants, visitors, contractors)
• What control measures are in place or needed

For most domestic properties with simple water systems (mains-fed, no storage tanks), the risk is low and a straightforward assessment by the landlord is sufficient. Complex systems (storage tanks, hot tubs, cooling towers) may require a specialist contractor.

Control Measures

• Flush through infrequently used outlets (taps, showers) regularly — at least weekly if the property is vacant
• Set hot water cylinders to store water at 60°C or above
• Ensure cold water is stored and distributed below 20°C
• Remove or insulate pipework that may cause water to heat up
• Clean and descale showerheads at least every 3 months
• Avoid dead-legs (sections of pipe with no flow) in the system

Record Keeping

You must keep records of:

• The risk assessment and date it was carried out
• Any control measures implemented
• Maintenance and inspection activities
• Any incidents or remedial actions taken

Records should be kept for at least 5 years.

When to Review

Review your risk assessment when:

• There is reason to believe it is no longer valid
• The water system is altered or extended
• A new tenant moves in after a void period
• There has been a case of Legionnaires' disease linked to the property

Using a Specialist Contractor

For complex systems, or if you are unsure, you should engage a competent contractor who is a member of a recognised trade body such as the Legionella Control Association (LCA). Even if you delegate the work, you remain legally responsible as the landlord.

Penalties for Non-Compliance

Failure to comply with Legionella control duties can result in prosecution under health and safety legislation, unlimited fines, and in serious cases, imprisonment. If a tenant contracts Legionnaires' disease due to your negligence, you may also face civil liability claims.