The Health and Safety Executive (HSE) confirmed in its Approved Code of Practice L8 (Legionella bacteria — the control of Legionella bacteria in water systems) that the duty of care extends to residential landlords. The HSE publication HSG274 Part 2 specifically addresses domestic hot and cold water systems, which are the primary Legionella risk in rental properties.
Most private rented properties present a low risk for Legionella if water systems are correctly designed and maintained. However, 'low risk' does not mean 'no duty'. Landlords must carry out a written risk assessment and, where risks are identified, put control measures in place. Failing to do so is a criminal offence under health and safety legislation.
What is your legal duty as a landlord?
Your Legionella obligations under UK law include:
- Risk assessment duty (COSHH Regulation 6): You must assess the risk from Legionella bacteria in your water systems and document your findings in writing. This applies to all residential rental properties in England
- Suitable and sufficient assessment: The risk assessment must be 'suitable and sufficient' for the property type and usage. For a standard single-occupancy residential letting with a conventional domestic water system, this can often be carried out by a competent landlord
- Control measures: Where risks are identified, you must implement control measures to eliminate or reduce them. Common measures include temperature management (water stored above 60C, delivered above 50C), flushing of infrequently used outlets, and removal of dead legs in pipework
- Record keeping: You must keep written records of your risk assessment and any control measures taken. Records should be retained and updated following any significant change to the water system or tenancy
- Review: The assessment must be reviewed when there is reason to believe it is no longer valid, such as after a long void period, after significant plumbing works, or following a change of tenant
What does a Legionella risk assessment involve?
For a typical residential rental property, a Legionella risk assessment covers the following areas:
- Water system schematic: Identify all hot and cold water sources, storage vessels (tanks, cylinders), pipework runs, and all outlets (taps, showers, garden hoses). Note any dead legs (pipes that lead to unused outlets)
- Temperature check: Cold water should be stored and supplied below 20C. Hot water should be stored at 60C or above in a cylinder, and distributed at 50C or above within one minute from any outlet. Tepid water in the temperature range 20-45C is the primary Legionella growth zone
- Condition of the system: Check for corrosion, scale, biofilm, or contamination. These provide nutrients for Legionella growth. Check showerheads for scale build-up
- Infrequently used outlets: Taps or showers that are not used weekly are higher-risk because stagnant water in pipework warms to Legionella-growth temperatures. Identify all such outlets
- Risk rating and record: Produce a written summary of the risk level (typically Low, Medium, or High), the findings, and any control measures or remediation required
Can a landlord carry out their own Legionella risk assessment?
For most standard domestic properties, yes — but the HSE's 'competent person' requirement must be met:
- Competent person standard: The HSE defines a 'competent person' as someone with sufficient knowledge, skills, and experience to identify, assess, and control Legionella risks. A landlord who has read HSG274 Part 2 and understands domestic hot and cold water systems can usually satisfy this for a standard property
- Low-risk properties: A typical domestic water system where hot water is stored in a cylinder at 60C, cold water is drawn directly from the mains (no cold water storage tank), and all outlets are used regularly, is generally low risk and suited to a landlord self-assessment
- Higher complexity properties: Older properties with cold water storage tanks in the loft, properties with complex pipework or dead legs, HMOs with many outlets, or properties with swimming pools, hot tubs, or spa systems, should be assessed by a qualified Legionella risk assessor
- Void periods: After a long void (the property has been empty for weeks), a professional assessment before re-letting is advisable. Stagnant water in a vacant property is a significant risk factor
- Documentation quality: Whether you carry out the assessment yourself or hire a professional, the written record is what demonstrates compliance. Template Legionella risk assessment forms are available from the HSE website
Control measures for common residential Legionella risks
If your risk assessment identifies issues, these are the standard control measures for residential properties:
- Temperature management: Set your hot water cylinder thermostat to 60C (not lower to save energy). At 60C, Legionella bacteria are killed within a few minutes. Temperatures below 50C dramatically increase survival times
- Weekly flushing of infrequently used outlets: Any tap or shower not used weekly should be run for 2-3 minutes each week, flushing fresh water through the pipework. Document the flushing schedule
- Cold water storage tank insulation and cover: If you have a cold water storage tank (common in older properties), ensure it has a tight-fitting lid and is insulated to keep cold water below 20C in summer. Remove any nearby heat sources
- Showerhead descaling: Limescale in showerheads creates an environment where Legionella can multiply. Clean and descale showerheads at least quarterly, or replace them at change of tenancy
- Remove dead legs: Capped-off pipes that retain stagnant water and cannot be flushed are significant Legionella risks. Arrange for a plumber to remove dead legs identified during the assessment
- Instruct your tenant: Inform tenants to report any problems with the hot water system (particularly if water is not hot enough from the hot tap) and to run garden hoses and infrequently used taps periodically
Record keeping and documentation
The Legionella records you should keep as a landlord:
- Written Legionella risk assessment dated and signed, with findings and risk ratings for each element of the water system
- Details of who carried out the assessment and their competency basis (own knowledge, third-party qualification, or professional assessor certificate)
- Control measures put in place following the assessment, with dates implemented
- Regular temperature check records (particularly for hot water cylinders and cold water tanks where applicable)
- Flushing schedule records if any outlets require weekly flushing
- Record of any plumbing works or system changes that triggered a reassessment
- Copies of professional Legionella assessor reports and certificates if a third-party assessor was used
Frequently asked questions
Is a Legionella risk assessment a legal requirement for all rental properties?+
Yes. The duty to carry out a Legionella risk assessment applies to all residential rental properties in England under the Health and Safety at Work etc. Act 1974 and COSHH Regulations 2002. However, for simple domestic water systems in standard properties where the risk is demonstrably low, the assessment can be brief and carried out by a competent landlord rather than a professional assessor. The key obligation is to have a written record of the assessment and any control measures taken.
How much does a professional Legionella risk assessment cost?+
For a standard residential property, a professional Legionella risk assessment from a CIBSE/Legionella Control Association (LCA) registered assessor typically costs between £60 and £200, depending on property size and complexity. HMOs and properties with cold water storage tanks or complex pipework cost more. The assessment is typically valid for 2 years unless the water system changes significantly or the property has a long void period.
Does Legionella risk increase during void periods?+
Yes significantly. Stagnant water in pipework warms to ambient temperature over several days. If that ambient temperature falls in the Legionella growth range (20-45C), which most properties will in summer, the bacteria can multiply rapidly over a void period of several weeks. Before re-letting after a void of more than 2 weeks, the recommended practice is to flush all outlets thoroughly and check hot water cylinder temperature before a new tenant moves in.
Can I be prosecuted if a tenant contracts Legionnaires' disease?+
In theory yes. If a tenant contracts Legionnaires' disease from water systems in your property and you cannot demonstrate that you carried out a suitable Legionella risk assessment and implemented appropriate control measures, you could face prosecution under the Health and Safety at Work etc. Act 1974. Prosecutions of individual landlords are rare but have occurred. The greater risk in practice is civil liability claims by an affected tenant if negligence in water system maintenance can be established.