When should you have a Legionella risk assessment reviewed according to ACoP L8?

If you manage a building with any type of water system, whether it is a rental home, office, factory, public building or care setting, you are legally required to control the risk of Legionella bacteria. A core part of this responsibility is ensuring a Legionella risk assessment is completed and reviewed regularly.

Many duty holders understand the need for an initial assessment, but fewer know how often it should be reviewed or what triggers the requirement to carry out a reassessment. This guide explains what HSE ACoP L8 actually requires, how to judge review frequency and why using a suitably qualified Legionella risk assessor is essential for compliance.

L8 Requirements: Regularly Reviewing the Legionella Risk Assessment

ACoP L8 places a clear duty on employers, landlords and anyone in control of premises to identify and assess Legionella risks, implement suitable control measures and review the assessment regularly. The guidance does not provide a fixed interval for how often a review must take place. Instead, it states that the frequency should be determined by the duty holder based on the level of risk.

In simple terms, the assessment must be reviewed often enough to ensure it remains valid and accurately reflects the current condition of the water systems.

How Often Should a Legionella Risk Assessment Be Reviewed?

Although L8 does not prescribe an exact timescale, industry best practice and supporting guidance in HSG 274 recommend a typical review every two years. Many organisations adopt this two-year cycle as part of their routine water hygiene compliance.

However, some environments require more frequent reviews. These include healthcare settings, care homes, large commercial buildings, older properties undergoing regular repairs and systems with stored hot water. Small, low-risk premises with simple domestic-style systems may justify a longer review period, but this must be confidently justified, well documented and supported by consistent monitoring results.

Ultimately, the review frequency must be based on risk, system complexity, occupancy patterns and how effectively the existing control measures are performing.

When Must a Legionella Risk Assessment Be Reviewed Immediately?

ACoP L8 and HSG 274 outline several situations where a review becomes mandatory, regardless of when the last assessment took place.

1. Changes to the Water System

Any modification, addition, removal or reconfiguration of the system triggers the need for a reassessment. This includes new pipework, system extensions, replacing tanks, pumps or calorifiers, adding or removing outlets and converting a building into flats or HMOs. Even small changes can affect temperatures, flow patterns or stagnation risk.

2. Changes in Building Use or Occupancy

A review must take place when the way a building is used changes. Examples include a vacant property being occupied, a business moving to hybrid or low occupancy, a shop being converted into a restaurant or new tenants with different water usage patterns. Occupancy changes often create low-use outlets, which increase the risk of Legionella growth.

3. Evidence That Control Measures Are Not Working

If the Legionella control scheme begins to fail, the risk assessment must be reviewed. Warning signs include consistently poor temperatures, inadequate flushing, scale build-up in shower heads or tanks, microbiological contamination in sampling results or repeated non-compliances during monitoring. A risk assessment should never remain unchanged when control measures are no longer effective.

4. A Case or Suspected Case of Legionnaires’ Disease

If someone associated with the premises contracts or is suspected of contracting Legionnaires’ disease, the assessment must be reviewed immediately.

5. After Long Periods of Inactivity

Buildings that are closed or only partially used for extended periods require a reassessment once reopened. This applies to schools during holidays, seasonal venues, accommodation blocks, vacant properties and offices that have been unused.

Why a Competent Person Must Carry Out the Review

ACoP L8 states that anyone completing or reviewing a Legionella risk assessment must be competent. In practice, this requires appropriate qualifications, such as City & Guilds Legionella risk assessment training, practical experience with a range of water systems, strong knowledge of HSG 274 Parts 1, 2 and 3, the ability to produce accurate schematics and a full understanding of hot and cold water system design.

A competent assessor must also be able to make clear, evidence-based recommendations.

For this reason, most organisations choose a professional Legionella risk assessor rather than completing assessments in-house. A qualified assessor ensures the findings are legally defensible and meet the standards expected by the HSE, insurers and auditors.

What Happens During a Review?

A Legionella risk assessment review typically includes checking changes to the water system, reviewing control measures and monitoring logs, reassessing temperatures and outlet usage, inspecting tanks, calorifiers and outlets, updating schematic drawings and risk scores, recommending improvements and confirming whether the system remains under control. This ensures your documentation is always accurate, compliant and up to date.

Summary: Legionella Risk Assessment Review Requirements Under L8

A risk assessment must be reviewed regularly, with the frequency determined by the duty holder based on risk. A two-year review period is typical, but higher-risk sites require more frequent reviews. Mandatory reviews are required when the water system changes, building use changes, control measures fail, a case of Legionnaires’ disease is suspected or the building has been inactive. All assessments and reviews must be completed by a competent, qualified assessor. This is not a box-ticking exercise but a crucial part of keeping people safe and ensuring legal compliance.

Book a Legionella Risk Assessment Review

If your assessment is due for renewal or you are unsure when it was last reviewed, we can help. Our City & Guilds qualified assessors carry out fully compliant Legionella risk assessments for landlords, commercial sites and multi-site organisations.

01226 491133

Support@absolute-water.co.uk

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