Legionella in the UK: What You Need to Know

Legionella bacteria are a recognised health risk in UK buildings. They occur naturally in freshwater like ponds, lakes and rivers but they become dangerous when they're allowed to grow in poorly managed water systems.

If you are responsible for a property, you have a legal duty to assess and control the risk.

What is Legionella?

Legionella bacteria can cause Legionnaires’ disease, a serious type of pneumonia. People become infected by inhaling droplets of water that contain the bacteria. This can happen through showers, spa pools, hot tubs, cooling towers or some air conditioning systems.

The bacteria grow in stagnant water and in hot and cold water systems where water temperatures sit between 20°C and 45°C.

It is not spread by drinking water. The risk comes from breathing in contaminated droplets.

What Are the Symptoms?

The symptoms of Legionnaires’ disease often begin like flu but can become more severe. They may include a persistent cough, feeling short of breath, chest pain and a high temperature.

Older adults, smokers and people with a weakened immune system are at greater risk. While cases of Legionnaires’ disease are not common, outbreaks still occur when systems are not properly managed.

What Does UK Law Require?

Under UK health and safety law, there is a clear legal duty to manage Legionella risk. The Health and Safety Executive sets out expectations through legislation such as the Health and Safety at Work Act and COSHH, supported by ACOP L8 guidance.

If you control a building, you must:

• Identify potential sources of legionella bacteria
• Carry out a legionella risk assessment
• Put suitable control measures in place
• Keep records and review them regularly

These are legal requirements, not optional steps.

Do You Need a Legionella Risk Assessment?

If your property has hot and cold water systems, water tanks, spa pools or stored water, the answer is almost certainly a yes.

A professional legionella risk assessment reviews the system design, water temperatures, areas of stagnation and current control measures. It identifies where conditions could encourage bacterial growth and recommends practical steps to reduce the risk of Legionnaires’ disease.

Managing the Risk in Practice

Effective control focuses on preventing growth and reducing exposure. This usually involves:

• Maintaining safe water temperatures
• Flushing unused outlets
• Cleaning and inspecting water tanks
• Monitoring systems and keeping records

These measures support safety at work obligations and demonstrate active compliance.

How Summit Environmental Can Help

Summit Environmental provides professional legionella risk assessment services. Our reports are clear, practical and focused on helping you to meet your legal requirements.

Contact us today to discuss Legionella risk assessments and protect your building with confidence.