Review frequency
How often should a legionella risk assessment be reviewed?
In England, Wales and Northern Ireland the law sets no fixed interval. HSE says to review the assessment periodically and whenever something changes. In Scotland, private landlords are expected to review it at least every two years.
Last reviewed October 2026 against HSE guidance.
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What HSE says
HSE's guidance for landlords states: “The law does not prescribe that the risk assessment be reviewed on an annual or biennial basis. It is important to review the assessment periodically in case anything changes.”
For smaller buildings generally, HSE says you must carry out a risk assessment and review it if there are significant changes, such as an extension to the water system or a change in the people using the building.
You will often see “every two years” quoted. That figure appeared in earlier editions of HSE's code of practice and is still widely used as a rule of thumb, and it is the stated maximum for private lets in Scotland. It is not a legal deadline in England, Wales or Northern Ireland.
When to review
| Trigger | Why it matters |
|---|---|
| Changes to the water system | A new boiler, cylinder, bathroom, or altered pipework can create dead legs or change stored temperatures. |
| A change of occupants | New tenants may include older or less healthy people, or use water differently. |
| A change in how the building is used | A home becoming an HMO, or an office changing its layout or hours, changes water turnover. |
| The property has stood empty | Stagnant water is one of the main risk factors. |
| Checks show controls are not working | For example, hot water not reaching 50°C at outlets or cold water above 20°C. |
| A case of Legionnaires' disease linked to the system | Review immediately and take specialist advice. |
| Nothing has changed for a long time | Look again periodically to confirm that is still true. |
A practical schedule
Where there is no legal interval, a written schedule shows you have thought about it. Many landlords and businesses settle on something like this:
- Simple rental property: review at each change of tenancy and at least every two years, tying it to another visit such as the gas safety check. HSE notes that checks can be made during mandatory visits where access is difficult.
- HMOs and shared systems: review annually, because occupants and usage change often.
- Workplaces: review in line with your written scheme, commonly every one to two years, and after any change listed above.
- Higher-risk premises such as care homes and healthcare: follow the specialist guidance for your sector and your water safety plan.
These are common practice, not legal requirements. Set the interval your own assessment justifies and write it on the form.
Review or new assessment?
A review checks whether the existing assessment is still valid. If the system, the occupants and the controls are unchanged, you note the date, confirm it still stands and set the next review.
If the review finds that the risk factors have changed, carry out a new assessment. The Scottish guidance puts it the same way: if a review indicates a change to the risk factors, a new risk assessment should be carried out.
Questions people ask
How often does a legionella risk assessment need to be done?
There is no fixed legal interval in England, Wales or Northern Ireland. HSE says to review it periodically and when anything changes. In Scotland private landlords are expected to review at least every two years.
Does a legionella risk assessment expire?
No. It has no expiry date in law. It stops being valid when it no longer reflects the system, the occupants or how the building is used.
Do I need a legionella risk assessment every year?
Not by law. Some agents, insurers and licensing schemes ask for annual reviews, and annual review is sensible for HMOs and higher-risk buildings, but the law does not set an annual requirement.
How often should a commercial legionella risk assessment be reviewed?
Review it regularly and whenever there is reason to think it is no longer valid, such as changes to the system or its use. Many businesses set a one to two year interval in their written scheme.
Sources
- HSE: Legionella and landlords' responsibilities
- HSE: Hot and cold water systems
- HSE: Approved Code of Practice L8, The control of legionella bacteria in water systems
- Scottish Government: Repairing Standard statutory guidance for private landlords, Annex D
Checked against these sources in October 2026. This page is general information, not legal advice.
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