How often do you need a legionella risk assessment?

What the law actually says

ACOP L8 requires the risk assessment to be reviewed regularly and specifically when there is reason to suspect it is no longer valid. Since the 2013 edition, the code names no fixed interval; the trigger is change, not the calendar (HSE legionella guidance).

The events that trigger a review

• Changes to the water system: new pipework, tanks removed or added, outlets capped, refurbishment.
• Changes to how the building is used: occupancy changes, a long void period, part of the building mothballed or brought back into use.
• Changes in the people: a new responsible person, or occupants who are more susceptible than the assessment assumed.
• Evidence control is failing: out-of-range temperatures, positive sample results, or a case of legionellosis associated with the premises.
• The original assessment ageing to the point where nobody can vouch that it still describes the system.

Why two years is still the working norm

Most assessors and property managers work to a two-year review cycle for ordinary premises, and older guidance did name two years, which is why the figure persists. It is defensible practice: a periodic re-check is a reliable way to catch changes nobody logged. But it is not a statutory deadline, and stating it as one is wrong in both directions, a premises that changed last month needs a review now, and an unchanged simple system does not become unlawful at 24 months.

What this means for your budget

Reviews of an existing assessment are typically priced below a first assessment because the assessor starts from the previous record, exact pricing depends on what has changed. A first assessment typically costs £60–£150 for a single rented property or small business and £200–£600+ for larger premises (typical 2026 quotes). Get both first-assessment and review prices via the form and diary the review against your own trigger events, not just a date.