How to complete a Legionella risk assessment

What is a Legionella risk assessment?

If your business premises has a water system (like taps, toilets, or showers), you have a legal duty to understand and control the health risks from Legionella bacteria. Completing a risk assessment is the first step. It involves identifying potential dangers, evaluating the level of risk, and putting in place practical measures to keep people safe. The key output is a written document that proves you have taken these steps.

In simple terms, Legionella is a type of bacteria common in natural water sources. It becomes a risk to health when it grows and spreads in man-made water systems. If people breathe in small droplets of contaminated water (aerosols), they can develop Legionnaires’ disease, a potentially fatal form of pneumonia.

Who needs to complete one?

This legal requirement applies to virtually all business owners, landlords, and anyone responsible for a building's water system. Whether you run a small shop with a staff toilet and kitchenette, a restaurant, a hotel, or manage an office block, you are responsible for ensuring the water system is safe for staff, customers, and visitors.

How to carry out the assessment

The process can be broken down into five key steps. For simple, small premises, you can often do this yourself if you feel confident. For larger, more complex buildings, you should hire a specialist water safety consultant.

1. Appoint a competent person
   This is the person responsible for the assessment. It can be you, a staff member, or an external expert. They don't need formal qualifications, but they must have the necessary knowledge and experience to identify risks and suggest controls.
2. Identify potential hazards
   Walk around your premises and list every part of the water system. This includes hot and cold water tanks, taps, showers, and air conditioning units. Look for factors that increase risk, such as water stored at temperatures between 20-45°C, rust, sludge or scale in the system, and outlets that are not used very often (like a shower in a spare room).
3. Evaluate the risks and implement controls
   For each hazard, decide who might be harmed and how. Then, put simple control measures in place. Common controls include:
   • Keeping hot water hot (at least 60°C in the tank, and 50°C at the taps).
   • Keeping cold water cold (below 20°C).
   • Flushing through infrequently used taps and showers for a few minutes at least once a week.
   • Regularly cleaning and descaling shower heads and tap attachments.
4. Record your findings
   You must keep a written record of your assessment. This document should detail what you found, the control measures you have put in place, and who is responsible for them. This is the proof that you are managing the risk correctly.
5. Review the assessment regularly
   This is not a one-off task. You should review the risk assessment at least every two years, or sooner if there are any changes to the water system or the building's use.

Keeping on top of your Legionella risk assessment is a vital part of your health and safety duties, ensuring your premises are safe for everyone.