The Legionella Control Cycle – Everything You Need to Know

If you operate a business or manage premises with a water system in the UK, Legionella control is not just a best practice,it’s a legal requirement. Legionnaires’ disease, a potentially fatal type of pneumonia, is caused by Legionella bacteria, which thrive in certain water systems if not properly controlled. The Legionella control cycle is a structured process that helps reduce the risk of exposure to Legionella and ensures your business complies with health and safety law.

In this guide, we’ll break down everything you need to know about the Legionella control cycle, including legislation, responsibilities, risk assessment, monitoring, and ongoing control measures. We’ll also highlight common compliance mistakes and how Absolute Water Compliance can help you avoid them.

What Is the Legionella Control Cycle?

The Legionella control cycle is a continuous process that ensures all aspects of a water system are managed, maintained, and monitored to minimise the risk of Legionella bacteria proliferation. 

The 6 stages of the legionella control cycle:

1. Identification & Responsibility 

2. Legionella Risk Assessment

3. Scheme of Control

4.

Monitoring and Record-Keeping

5. Remedial Actions and Reviews

6. Training and Awareness

Each stage is critical to ensure compliance with HSE’s Approved Code of Practice L8 (ACoP L8) and HSG274 technical guidance.

1. Identifying Roles and Responsibilities

Before anything else, your business must appoint a Responsible Person—someone competent, trained, and authorised to oversee Legionella control.

Who should be the Responsible Person?

This individual can be a facilities manager, health and safety officer, or another senior team member. The responsible person may delegate tasks but retains ultimate accountability.

What legal responsibilities do I have as a business? 

Under the Health and Safety at Work Act 1974, COSHH (Control of Substances Hazardous to Health Regulations 2002), and ACoP L8, duty holders must ensure the safety of anyone exposed to risks from Legionella.

Top Tip:

Even if you outsource tasks, you must ensure that your contractors are competent and that control measures are working.

2. Legionella Risk Assessment (The Starting Point)

Your first tangible step in the cycle is conducting a Legionella risk assessment—this forms the foundation of your entire control strategy.

What’s Included in a Legionella Risk Assessment? 

A detailed survey of all water systems (hot, cold, closed, and open systems)

Identification of risk areas where water is stored, recirculated, or aerosolised

Review of temperatures, stagnation points, and biofilm risk

Assessment of current control measures and documentation

When Should You Do It?

Every 2 years as a minimum or when there are significant changes to the water system or building use.

After building refurbishment, water system changes, or staff turnover affecting responsibility.

Did You Know?

Many businesses fail to reassess after refurbishment or changes in usage, leaving them non-compliant and at risk.

3. Developing a Legionella Scheme of Control

Once risks are identified, you must develop and implement a written scheme of control. This is a live document that outlines how you'll manage the identified risks.

The Scheme Should Include:

• Names of responsible persons and their roles 

• Details of the water system (schematics and assets)

• Routine monitoring schedules (temperature checks, inspections)

• Flushing procedures

• Disinfection protocols (if applicable)

• Contingency procedures in the event of an outbreak

This document must be accessible to anyone involved in water system management or maintenance.

4. Ongoing Monitoring and Record Keeping

This is where many businesses fall short. Monitoring must be consistent, accurate, and well-documented. It's not just about ticking boxes—it's about proving control.

What Needs Monitoring?

Temperatures: Hot water should be ≥ 50°C (55°C in healthcare); cold ≤ 20°C

Tank Inspections: Look for scale, biofilm, or debris.

Showers and Outlets: Check for infrequent use or stagnation 

Water Sample Testing: In higher-risk environments (e.g. hospitals), microbiological testing may be required.

Records Must Include:

• Date, time, and location of checks

• Name of person completing the task

• Readings or observations 

• Corrective actions taken, if necessary

• Records should be kept for at least five years to demonstrate ongoing compliance.

5. Remedial Actions and Reviews.

Remedial measures are required in Legionella control to prevent the growth and spread of Legionella bacteria, which can cause Legionnaires’ disease a  potentially severe and sometimes fatal form of pneumonia. These bacteria thrive in water systems such as cooling towers, hot and cold water systems, and spa pools, especially when water temperatures and conditions are favorable.

Where issues are found, you must act—swiftly and appropriately. Delaying can result in serious health risks and legal consequences

Typical Remedial Works Include:

Replacing dead legs or little-used pipework

Installing thermostatic mixing valves

Tank cleaning or replacement

Pipework reconfiguration to eliminate stagnation

Once remedials are complete, a follow-up risk assessment or review is recommended to ensure changes are effective.

6. Training and Competency

Even the best control plan fails without competent people. Training is often overlooked—but it's legally required.

Training Should Cover: 

Legionella awareness and risk

Roles and responsibilities

System schematics

Practical tasks like flushing and monitoring

All training should be documented and updated regularly—especially when team members change or responsibilities shift.

Common Legionella Compliance Mistakes

Understanding what can go wrong is vital.

Here are some non-obvious problems that catch businesses off guard:

✅ Non-Use of Outlets

Unused taps, showers, and pipes allow bacteria to thrive. Flushing must be done weekly, but often gets missed when staff work remotely or facilities are partially closed.

✅ Inadequate Documentation

Poorly kept logs, missing signatures, or incomplete actions are red flags during audits and inspections.

✅ Failure to Update Risk Assessments

Businesses often assume one assessment is enough for years. But if the building use changes, the assessment is no longer valid.

✅ Using Non-Competent Contractors

Using the cheapest provider may save money short-term, but poor assessments or missed risks can lead to costly fines and reputational damage.

What are the possible repercussions and Costs of Non-Compliance?

Breaches of Legionella regulations can lead to: 

• HSE investigations and improvement notices

• Unlimited fines

• Criminal prosecution of directors or duty holders

• Reputation loss and business disruption

• 
  

A real-world case in the UK saw a company fined £1.8 million after a Legionnaires’ outbreak caused multiple illnesses and deaths due to poorly maintained cooling towers. 

How Absolute Water Compliance Helps

At Absolute Water Compliance, we specialise in supporting businesses through every step of the Legionella control cycle. We're family-run, UK-wide, and focused on practical, compliant solutions that keep you safe and legally protected.

✅ What We Offer: 

Legionella Risk Assessments (UK-wide coverage) 

Written Schemes of Control 

Monitoring and Logbook Services

Remedial Plumbing Work 

Training and Competency Support

Ongoing Reviews and Compliance Audits 

✅ Why Use Absolute Water Compliance, for your water compliance requirements; 

We don’t just hand over a report, we stay with you through implementation. Additionally we ensure that you have a personalised service from qualified engineers. Take a look at our reviews to see real life feedback. We offer transparent  pricing and practical advice.

Your Next Step: Stay Compliant and Protect Lives

The Legionella control cycle is not a one-time task—it’s a continuous loop of assessment, action, monitoring, and review. Compliance isn't just about ticking boxes; it's about protecting people’s health and fulfilling your legal obligations.

Whether you run an office, factory, care home, school, or commercial premises, you must ensure your water systems are managed safely

📞 Need Help or Have Questions?

We’re here to help with every stage of the Legionella control cycle. Get in touch for a no-pressure conversation or to request a quote.

📧 Email: support@absolute-water.co.uk

🌐 Website: www.absolute-water.co.uk

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