Legionella Risk Assessment (UK)

If you are responsible for premises with a water system, and almost every business is, the law expects you to understand and control the risk of legionella. A legionella risk assessment is the written assessment that shows you have done so. It is not only for cooling towers; a simple hot and cold water system can grow the bacteria too.

Why it is required

Legionella bacteria cause Legionnaires disease, a potentially fatal form of pneumonia, when contaminated water droplets are breathed in. The duty to assess and control the risk comes from the Health and Safety at Work etc. Act 1974 and the Control of Substances Hazardous to Health Regulations 2002. The detail is set out in the Approved Code of Practice L8 and the technical guidance HSG274. Because L8 is an approved code, a court will take a failure to follow it as evidence against you unless you can show you did something equally effective.

Who has to do it

The duty falls on the person in control of the premises, the duty holder: an employer, a landlord of business or residential premises, or whoever is responsible for the water system. Landlords of residential property are included, which catches a great many small businesses and letting agents who assume the rules do not apply to them.

What the assessment covers

1. A description of the water system, ideally with a simple schematic.
2. Potential sources of risk: stored water, temperatures between 20 and 45 degrees, stagnation in little used outlets, scale, rust and biofilm, and anything that creates a spray such as showers or taps.
3. Who could be exposed, including anyone more vulnerable.
4. The controls: keeping hot water hot and cold water cold, flushing little used outlets, removing dead legs, and a monitoring schedule.
5. Who is responsible for carrying out and recording the checks.

Who can carry it out

You can assess a simple system yourself if you are competent to understand it and the risks; many small landlords do. Larger or more complex systems, such as those with cooling towers or care settings, usually need a specialist. Competence, not a particular qualification, is the legal test.

Reviewing it

Review the assessment regularly and whenever the system changes, there is reason to think it is no longer valid, or a case of disease is linked to the premises. Two years is a common review interval for a stable low risk system, but there is no fixed figure in law.

Record it properly

Our risk assessment template gives you a clear structure to record the system, the hazards and the controls in the form an inspector or insurer expects. Pair it with our guide to writing a risk assessment if you want the method first.