If you are responsible for a building’s water system, one of the most common questions is how often a Legionella risk assessment needs to be carried out. The short answer is that there is no single fixed legal interval, but there are clear rules about when your assessment must be reviewed, and sensible good-practice timescales to follow. This guide explains both.
Is there a legal time limit for a Legionella risk assessment?
No. Under the Health and Safety Executive’s Approved Code of Practice (ACOP L8) and guidance HSG274, the law does not set a fixed expiry date for a Legionella risk assessment. Instead, it requires that the assessment is reviewed regularly and remains up to date. The duty holder must make sure it still reflects the real condition and use of the water system at all times.
In practice this means a risk assessment is not a one-off document. It should be treated as a living record that is revisited whenever circumstances change.
When you must review your risk assessment
ACOP L8 says you should review the assessment whenever there is reason to believe it is no longer valid. That includes:
- Changes to the water system or how it is used, such as new pipework, tanks, outlets or equipment
- Changes to the use of the building, or periods when parts of it stand empty
- Changes in occupancy, especially where vulnerable people are present
- New information about risks or control measures
- Control measures that are no longer effective, or monitoring results that drift out of range
- A suspected or confirmed case of Legionnaires’ disease linked to the system
- A change in the responsible person or duty holder
The “every two years” guideline
Because the law does not give a number, a widely used rule of thumb is to review a Legionella risk assessment at least every two years, even if nothing has obviously changed. This is good practice rather than a legal requirement, and it gives a clear, defensible schedule for most low to medium-risk premises. Higher-risk sites usually need reviewing more often, as set out below.
Higher-risk premises need more frequent reviews
Where the consequences of an outbreak are more serious, or the system is more complex, reviews should be more frequent, often annually. This typically applies to:
- Care homes and healthcare settings
- Premises used by elderly, very young or immunocompromised people
- Buildings with cooling towers, spa pools or complex hot and cold water systems
- Properties with a history of control problems or high Legionella counts
Don’t confuse the review with ongoing monitoring
The risk assessment review is separate from the routine monitoring that keeps the system safe day to day. Even with a valid risk assessment in place, tasks such as monthly temperature checks, quarterly showerhead cleaning and descaling, and tank inspections continue on their own schedules. The risk assessment sets out what those checks should be; the review makes sure the plan itself is still correct. If you are unsure what your assessment should include, our guide on what Legionella testing involves explains the practical side.
Who is responsible?
Responsibility sits with the duty holder, usually the employer, building owner or person in control of the premises, who should appoint a competent responsible person to manage Legionella control. Keeping the risk assessment current is part of that legal duty of care. Our overview of who needs a Legionella risk assessment covers this in more detail.
Frequently asked questions
Does a Legionella risk assessment expire after two years?
Not legally. There is no fixed expiry date. Two years is a common good-practice review interval, but the assessment must be reviewed sooner if anything changes that could affect the risk.
How often should a landlord do a Legionella risk assessment?
Landlords must assess and control the risk and review the assessment periodically, commonly every two years for a typical rental property, or sooner if the water system or tenancy changes.
Is a Legionella risk assessment a legal requirement?
Yes. Controlling Legionella risk is a legal duty under the Health and Safety at Work etc. Act 1974 and COSHH, with ACOP L8 setting out how to comply. A suitable and sufficient risk assessment is the starting point.
Need a Legionella risk assessment or review?
London Water Treatment carries out ACOP L8 compliant Legionella risk assessments and reviews across London, with clear written reports and practical control advice. You can also see our guide to Legionella risk assessment costs. Call 020 4532 7773 or get in touch for advice or a quote.