How Often Should a 
Legionella Risk Assessment be reviewed?

Is there a legal time limit?

No. Neither the law nor HSE sets a fixed date on which an assessment expires. The duty is to review it regularly and whenever there is reason to think it is no longer valid. A two-year cycle is common practice and a sensible benchmark, but it is not an HSE requirement, and it isn't enough on its own if something has changed in between.

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What triggers an early review?

Review your assessment straight away if any of these happen:

• Changes to the water system. New or altered pipework, tanks, calorifiers, showers or taps.

• Changes to how the building is used. A change of use, a refurbishment, part of the building closing or reopening.

• Changes to who uses it. New vulnerable occupants, such as older people, young children or people with weakened immune systems.

• Failed checks. Temperatures outside the required range, or monitoring showing controls aren't working.

• A positive sample. Legionella found in a water test.

• A case of Legionnaires' disease linked to the premises.

• New information. Updated HSE guidance or new knowledge about your risks.

• Changes to key staff. For example, the person responsible for water safety leaves.

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How often should higher-risk premises review?

Premises with vulnerable people or complex systems need closer attention. Care homes, hospitals, schools, nurseries, hotels, leisure centres and buildings with cooling towers or spa pools are usually reviewed more often than a small office. Your assessor can advise on a review schedule suited to your premises.

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What is the difference between a review and a new assessment?

A review checks whether your existing assessment is still accurate and updates it where things have changed. A new assessment starts from scratch with a full survey.