Legionella Regulations in the UK: A Complete Compliance Guide

19th March 2025

Everything You Need to Know About Legionella L8 Compliance Regulations

Legionella bacteria pose a serious health risk, particularly in workplaces, rental properties, and public buildings. If left unmanaged, these bacteria can multiply in water systems, leading to Legionnaires’ disease, a severe form of pneumonia. That’s why complying with UK legionella regulations is a legal and ethical responsibility for businesses, landlords, and property managers.

This guide breaks down the key UK legionella regulations, explains how to comply, and outlines best practices for keeping your water systems safe.

What Is Legionella Bacteria?

Legionella is a naturally occurring bacteria found in freshwater environments, but it becomes dangerous when it grows in man-made water systems where temperatures range between 20°C and 45°C. When water droplets contaminated with legionella are inhaled, they can cause Legionnaires’ disease, which can be fatal if not treated promptly.

Common Sources of Legionella Growth

Legionella bacteria can thrive in:

Hot and cold water systems (e.g., taps, showers, and storage tanks)
Cooling towers and evaporative condensers
Spa pools, jacuzzis, and swimming pools
Air conditioning and humidifier systems
Water fountains and decorative water features

Because legionella spreads through aerosolised water droplets, it is essential to control water temperature, reduce stagnation, and perform regular maintenance to prevent bacterial growth.

Why Are Legionella Regulations Important?

UK legionella regulations exist to protect public health and prevent outbreaks of Legionnaires’ disease. Failure to comply can result in hefty fines, reputational damage, and even criminal prosecution. The Barrow-in-Furness outbreak in 2002, which led to seven deaths, highlights the dangers of poor water system management.

Under UK law, businesses, landlords, and duty holders must take reasonable steps to control legionella risks and ensure compliance with safety regulations.

Key UK Legionella Regulations

There are several laws and guidelines governing legionella risk management in the UK. The most important include:

1. The Health and Safety at Work etc. Act 1974 (HSWA)

This legislation requires employers, landlords, and building managers to ensure their premises are safe for occupants. Under HSWA, controlling legionella bacteria is a legal duty.

2. The Control of Substances Hazardous to Health Regulations 2002 (COSHH)

COSHH classifies legionella as a hazardous substance, requiring businesses to:

Identify potential sources of exposure.
Implement control measures to reduce risk.
Train employees on safe water management.
Conduct regular monitoring and risk assessments.

3. The Management of Health and Safety at Work Regulations 1999 (MHSWR)

This law mandates risk assessments for any potential hazards, including waterborne bacteria. Employers and landlords must assess, control, and document legionella risks.

4. Notification of Cooling Towers and Evaporative Condensers Regulations 1992

Any premises with cooling towers or evaporative condensers must register them with the local authority. This helps prevent outbreaks by ensuring these high-risk systems are monitored properly.

5. The Reporting of Injuries, Diseases and Dangerous Occurrences Regulations 2013 (RIDDOR)

If a case of Legionnaires’ disease is linked to your premises, it must be reported to HSE (Health and Safety Executive) as a serious workplace illness.

How to Comply with Legionella Regulations

To meet legionella L8 compliance regulations, duty holders must take the following steps:

1. Conduct a Legionella Risk Assessment

A legionella risk assessment is legally required under ACoP L8 (Approved Code of Practice). It should:

Identify potential sources of legionella growth.
Assess who is at risk (e.g., elderly or immunocompromised individuals).
Outline control measures to prevent bacterial growth.
Be carried out by a competent person (someone with the right training and expertise).

For complex water systems, hiring a legionella risk assessment specialist is recommended.

2. Implement a Legionella Management Plan

Once risks are identified, you need a legionella control plan that includes:

Temperature control (keeping hot water above 50°C and cold water below 20°C).
Flushing unused outlets to prevent stagnation.
Water treatment measures such as chlorination.
Cleaning and descaling shower heads, pipes, and water tanks.

3. Appoint a Competent Person (Responsible Person)

The duty holder must assign a competent person to oversee legionella management. This can be an internal employee or an external water safety specialist.

4. Keep Detailed Records

Under HSE’s ACoP L8, businesses with five or more employees must maintain written records for:

Risk assessments (kept for at least 2 years).
Monitoring, testing, and inspections (kept for 5 years).
Any actions taken to manage legionella risk.

Even if your business is small, keeping accurate records is highly recommended.

5. Regular Water Testing and Monitoring

Regular legionella testing should be performed:

Every three months for cooling towers.
Annually for low-risk water systems.
More frequently if control measures are not working.

Testing methods include:

Culture testing (laboratory analysis).
PCR (Polymerase Chain Reaction) testing (rapid detection).
Dip slides and swabs for routine checks.

Understanding ACoP L8 and HSG274 Guidance

The Health and Safety Executive’s ACoP L8 is the gold standard for legionella control in the UK. It provides detailed best practices for managing water systems safely.

HSE also publishes HSG274, a three-part guidance document covering:

Following ACoP L8 and HSG274 ensures full compliance with UK legionella regulations.

Legionella Regulations for Landlords

Landlords must ensure rental properties are safe from legionella risks. This includes:

Conducting a legionella risk assessment (even for domestic properties).
Keeping water systems clean and free from stagnation.
Informing tenants of any legionella risks and prevention measures.

Although HSE does not require landlords to perform routine legionella testing, a risk assessment is mandatory.

What Happens If You Don’t Comply?

Failure to comply with UK legionella regulations can result in:

Unlimited fines and criminal prosecution.
Building closure or loss of business.
Reputational damage from public health violations.
Serious illness or fatalities from Legionnaires’ disease.

Recent data shows that positive legionella samples increased by 20% after lockdown, highlighting the importance of ongoing water system management.

Final Thoughts on UK Legionella Regulations

Legionella compliance is not just a legal requirement—it’s a crucial step in protecting public health. Whether you’re a business owner, landlord, or facilities manager, following ACoP L8 and HSG274 ensures your water systems remain safe and compliant.

For expert guidance, consider partnering with legionella specialists who offer risk assessments, water testing, and compliance support.

By staying proactive, you can avoid legal risks, protect occupants, and ensure a safe water supply.

Click the link for more information on Legionella control measures & guidance.

FAQs

What is Legionnaires’ disease?

Legionnaires’ disease is a severe form of pneumonia caused by inhaling Legionella bacteria from contaminated water droplets.

Do landlords need to comply with legionella regulations?

Yes, landlords must conduct legionella risk assessments and ensure their properties meet HSE’s ACoP L8 standards.

How often should water systems be tested for legionella?

Testing should be quarterly for high-risk systems (e.g., cooling towers) and annually for low-risk systems.

What are the penalties for non-compliance?

Non-compliance can result in unlimited fines, prosecution, and even imprisonment in severe cases.

Where can I get professional help for legionella compliance?

Legionella specialists offer risk assessments, testing, and compliance services to help businesses meet UK legionella regulations.