Legionella Risk Assessments

If you're an employer, landlord or building owner responsible for a water system, whether that's hot and cold water services, cooling towers or storage tanks, you have a legal duty to assess and control the risk of legionella bacteria. This duty comes from the Health and Safety at Work Act 1974 and the Control of Substances Hazardous to Health Regulations (COSHH) 2002, and is set out in the Health and Safety Executive's Approved Code of Practice L8 and supporting HSG274 guidance.

What a Risk Assessment Involves

We survey the property's water system, working from schematics or drawings where available, to identify anything that could allow legionella bacteria to grow and spread. That includes checking hot and cold water temperatures against HSE guidance: hot water should be stored at 60°C or above and reach at least 50°C at outlets, while cold water should stay below 20°C, since legionella grows fastest between 20°C and 45°C. We also look for dead legs of unused or rarely used pipework, check thermostatic mixing valves where fitted, and note any infrequently used outlets that need regular flushing.

Who's Responsible

Responsibility sits with whoever has control of the premises or water system, often called the duty holder. In practice, this usually means appointing a named responsible person to manage a written control scheme, keep monitoring records, and make sure control measures are actually being carried out, not just documented.

Ongoing Monitoring & Review

A risk assessment isn't a one off exercise. It needs to be reviewed whenever something changes, such as new pipework, altered usage, or a problem picked up during routine checks, and as good practice at least once a year. Records should be kept for a minimum of 5 years. We can carry out the initial assessment, put routine monitoring in place, and review it as your property changes.

Higher Risk Properties

Some properties carry a higher risk than others, including care homes, hotels and other hospitality settings, and rented properties such as HMOs with complex or intermittently used water systems. If your property falls into one of these categories, or simply hasn't had an assessment before, it's worth getting one in place sooner rather than later.