Legionella Risk Assessment: The Must-Know Guide for UK Businesses

Legionella bacteria pose a serious and often underestimated risk within any building that uses water systems. These bacteria can multiply rapidly in stagnant or poorly maintained water, particularly when temperatures are between 20°C and 45°C — conditions commonly found in storage tanks, pipes, and showers. When contaminated water droplets are inhaled, they can cause Legionnaires’ disease, a severe form of pneumonia that can be fatal, especially for individuals with weakened immune systems or underlying health conditions.

For business owners, landlords, and duty holders, the implications of a Legionella outbreak are far-reaching. Beyond the immediate health risk, organisations can face heavy legal penalties, lasting reputational damage, and even prosecution. This makes Legionella risk assessments not just best practice, but a legal necessity under UK health and safety law.

In this guide, we will break down everything you need to know about managing Legionella risk in your property. You’ll learn about the legal framework surrounding Legionella control, step-by-step compliance requirements, and what to expect during an assessment.

We’ll also cover written schemes of control, staff training obligations, remedial work, ongoing monitoring, and the importance of accurate record keeping. By the end, you’ll have a clear understanding of your responsibilities and how to keep your premises safe, compliant, and protected.

1. The Legal Expectations: What the Law Says About Legionella

UK legislation places a clear and enforceable duty on businesses, landlords, and other responsible persons to identify, assess, and control the risks associated with Legionella bacteria. Several key pieces of legislation underpin this responsibility. The Health and Safety at Work etc. Act 1974 establishes a general duty for employers and landlords to ensure the health and safety of employees, tenants, and visitors. The Control of Substances Hazardous to Health (COSHH) Regulations 2002 further classifies Legionella as a hazardous substance that must be managed and controlled to prevent exposure.

Additionally, the Management of Health and Safety at Work Regulations 1999 requires organisations to carry out risk assessments to identify potential hazards and put appropriate control measures in place. The most authoritative guidance, however, comes from the HSE’s Approved Code of Practice (ACoP L8), which sets out the essential steps for preventing and controlling Legionella in water systems.

In practical terms, this means that every business with a water system, from an office kitchen to a hospital’s hot water network — must take proactive measures. You are legally required to conduct a Legionella risk assessment, appoint a competent responsible person, implement a Written Scheme of Control, and maintain thorough records of monitoring, training, and remedial actions. Failure to comply with these duties can result in HSE enforcement, substantial fines, and, in serious cases, imprisonment. In short, if your building uses water, you have a duty to control Legionella.

2. Compliance: What You Must Do Step by Step

Achieving compliance with Legionella control regulations is not a one-time exercise; it is an ongoing cycle of assessment, monitoring, and review. The process begins with a comprehensive Legionella risk assessment, which must be conducted by a trained and competent professional. This assessment identifies potential hazards, evaluates the risk of exposure, and provides a plan for managing and reducing that risk. It should be reviewed regularly — typically every two years — or sooner if there are significant changes to the water system, building layout, or its usage.

A Legionella policy should also be in place, clearly outlining your organisation’s commitment to Legionella control, defining roles and responsibilities, and establishing escalation procedures in the event of an issue. The next step is developing a Written Scheme of Control, a site-specific document that details how risks will be managed on an ongoing basis. This scheme should outline flushing regimes, temperature monitoring schedules, cleaning procedures, and emergency response actions.

Staff training is another critical element. All individuals who work with or around water systems — including maintenance teams, cleaners, and contractors, should be given appropriate Legionella awareness training. This ensures that everyone understands the importance of water hygiene and knows how to recognise and respond to potential risks.

Monitoring activities, such as flushing outlets, temperature checks, tank inspections, and descaling of showerheads, must be conducted regularly. Each of these tasks should be recorded meticulously. Accurate record keeping is a legal requirement, with all records retained for at least five years and made available for HSE inspection if requested. Where issues are identified, prompt remedial action,such as cleaning tanks, removing redundant pipework, or upgrading system components,must be taken.

Ultimately, compliance is not about paperwork; it’s about maintaining an active and effective control system that protects both people and property.

3. What to Expect from a Legionella Risk Assessment

When you commission a Legionella risk assessment, a competent assessor will carry out a structured and detailed evaluation of your premises. The process begins with a site inspection, during which the assessor examines all relevant water systems, including tanks, calorifiers, pipework, and outlets, to identify potential risk areas. The assessment also involves system mapping, highlighting features such as dead legs, infrequently used outlets, and any areas where water stagnation could occur.

Temperature measurements are taken throughout the system to ensure that both hot and cold water are being stored and circulated at safe temperatures. The assessor will also review existing documentation, such as maintenance records, temperature logs, and previous risk assessments, to confirm that monitoring procedures are being followed correctly.

Following the site visit, you will receive a comprehensive written report. This report outlines all identified risks, categorises them by severity, and provides clear recommendations for remedial actions. Using a professional, competent assessor is essential — a DIY checklist or generic online form will not meet HSE standards or provide adequate legal protection.

4. The Legionella Written Scheme: What It Is and Who Writes It

The Written Scheme of Control is one of the most critical components of any Legionella management programme. It serves as your operational plan for maintaining safe water systems and sets out how identified risks will be controlled. A compliant Written Scheme includes a full description of your water system, ideally supported by schematics or diagrams, as well as the identification of risk areas and specific control measures such as temperature monitoring, flushing, disinfection, and regular maintenance schedules.

The scheme also defines roles and responsibilities, ensuring accountability across your organisation, and outlines the steps to be taken if Legionella is detected or if monitoring results fall outside safe parameters. This document must be site-specific and written by a qualified and competent professional, generic templates or copied examples will not meet legal standards.

5. Training Requirements: Who Needs Training?

Effective Legionella control depends on knowledgeable people. While the law requires a designated responsible person to oversee Legionella management, it is essential that everyone involved in maintaining or interacting with water systems receives suitable training. This includes maintenance operatives, caretakers, cleaners, and external contractors.

Training should cover the basics of Legionella awareness, the health risks involved, and the specific control measures relevant to your site. Refresher training should be conducted at least every two years or whenever significant changes are made to the system. Well-trained staff are your first line of defence in maintaining compliance and preventing risk.

6. Ongoing Monitoring: Beyond Flushing and Temperature Checks

Monitoring water systems is an ongoing responsibility and goes far beyond simple flushing routines. A comprehensive monitoring regime should include regular temperature checks, inspection of tanks and calorifiers, cleaning and descaling of outlets, and microbiological sampling where appropriate.

These activities are vital to confirm that your control measures are effective and that the system continues to operate safely. Regular audits of your processes, including reviewing logbooks and assessing compliance with the Written Scheme of Control, help identify areas for improvement and ensure that small issues do not become major problems.

Remember, flushing and temperature checks alone are not enough. Monitoring must be proactive, systematic, and supported by accurate documentation.

7. Remedial Work: Fixing Problems at the Source

When issues are identified during an assessment or through ongoing monitoring, prompt remedial action is essential. Common corrective works include removing dead legs — sections of pipework where water sits unused — as well as cleaning or replacing water tanks, upgrading calorifiers, or improving system design to reduce stagnation. Ensuring that hot water is consistently delivered at 60°C and cold water is maintained below 20°C is one of the most effective ways to control bacterial growth.

All remedial work should be performed by qualified professionals with experience in water hygiene management. Delays or incomplete fixes can leave your system vulnerable and may constitute a breach of your legal duty.

8. Legionella Sampling: When Is It Needed?

While routine sampling is not required for all standard water systems, there are circumstances where it becomes essential. Sampling should be carried out if there is any doubt about the effectiveness of your control measures, if vulnerable populations are served by the system (such as in hospitals or care homes), or if a case of Legionnaires’ disease is suspected. Sampling is also mandatory in high-risk environments like cooling towers, evaporative condensers, and spa pools.

Samples must always be sent to UKAS-accredited laboratories, and results should be interpreted by a competent professional who can advise on appropriate corrective actions. Testing is only one part of the picture — it must form part of a broader risk management strategy.

9. Record Keeping: Why It’s Essential

Good record keeping is a cornerstone of Legionella compliance. You must maintain accurate, up-to-date records of all risk assessments, temperature checks, flushing routines, remedial works, sampling results, and training activities. These records should be stored securely and retained for a minimum of five years.

Keeping detailed records not only demonstrates compliance during HSE inspections but also provides valuable evidence in the event of an investigation or outbreak. Moreover, reviewing historical data can help you identify recurring issues and track the effectiveness of your control measures over time. Without proper records, even the best control programme may be deemed non-compliant.

Conclusion: Stay Compliant, Stay Protected

Managing the risk of Legionella is both a legal obligation and a moral responsibility. A robust control programme should include a comprehensive risk assessment, a tailored Written Scheme of Control, ongoing monitoring, staff training, and accurate record keeping. Together, these elements create a continuous cycle of prevention and improvement that keeps your building safe and compliant.

At Absolute Water Compliance, we specialise in helping businesses across South and West Yorkshire implement effective Legionella control programmes. Our expert team provides detailed risk assessments, written schemes, remedial works, and staff training — all tailored to the specific needs of your site and industry.

Protect your business, your people, and your reputation with expert Legionella management from a trusted compliance partner.

📞 Call us today: 01226 491133

📧 Email: support@absolute-water.co.uk

🌐 Learn more: Absolute Water Compliance – Legionella Risk Assessment