How to Prevent Legionella in Commercial Buildings (And Stay Compliant)

If you’re responsible for a commercial building, Legionella control isn’t optional, it’s a legal and safety-critical responsibility.

Failing to manage the risk can lead to outbreaks of Legionnaires' disease, significant fines, and reputational damage. But with the right approach, Legionella is entirely preventable.

This guide breaks down exactly how to reduce risk, and how to ensure your building remains compliant with UK regulations.

Why Legionella Is a Serious Risk in Commercial Buildings

Legionella bacteria grow in water systems where conditions allow them to multiply. Commercial environments are particularly vulnerable due to:

• Complex water systems

• Inconsistent usage (leading to stagnation)

• Multiple outlets (showers, taps, tanks, cooling systems)

Without proper controls, these systems can become a breeding ground for harmful bacteria.

Your Legal Duty: What You Must Do

In the UK, businesses must comply with ACoP L8, which outlines your responsibilities.

You are required to:

• Identify and assess Legionella risks

• Implement control measures

• Maintain and monitor systems

• Keep accurate records

• Appoint a responsible person

If you don’t have these in place, you are not compliant.

7 Essential Steps to Prevent Legionella

1. Carry Out a Legionella Risk Assessment

A professional risk assessment identifies where Legionella could grow and who may be at risk.

This is the foundation of your entire control strategy, and a legal requirement.

Temperature control

Temperature control is one of the most effective ways to prevent Legionella growth. Hot water should be stored at 60°C or above, distributed so that it reaches outlets at at least 50°C, and cold water should be maintained at below 20°C. Keeping water outside the temperature range in which Legionella bacteria thrive helps significantly reduce the risk of multiplication and spread.

3. Eliminate Water Stagnation

Stagnant water = high risk.

Reduce it by:

• Flushing unused outlets weekly

• Removing redundant pipework

• Ensuring proper circulation

This is especially important in offices, schools, and seasonal buildings.

4. Clean and Maintain Systems

Regular maintenance reduces biofilm and contamination:

• Clean water tanks

• Descale taps and showers

• Inspect cooling systems

• Remove sludge and debris

  
  

5. Monitor and Test Regularly

Ongoing monitoring ensures your system stays safe:

• Temperature checks

• Water sampling

• System inspections

Documentation is critical for compliance and audits.

6. Use Water Treatment Where Needed

Some systems require additional control methods such as:

• Chlorination

• Biocides

• UV treatment

The right solution depends on your system design and risk level.

7. Train Staff and Assign Responsibility

You must appoint a competent responsible person to manage Legionella control.

Training ensures:

• Procedures are followed

• Risks are understood

• Compliance is maintained

  
  

High-Risk Situations You Shouldn’t Ignore

Certain scenarios significantly increase Legionella risk:

• Buildings left empty or underused

• Seasonal shutdowns

• Changes to water systems

• Poor maintenance history

If any of these apply to you, your risk level is higher than you think.

The Cost of Getting It Wrong

Ignoring Legionella control can result in:

• Serious illness or fatalities

• Legal prosecution

• Large fines

• Business disruption

More importantly, it puts people at risk.

How We Can Help

Managing Legionella properly takes time, expertise, and consistent oversight.

That’s where we come in.

We provide:

• Professional Legionella risk assessments

• Ongoing monitoring and compliance support

• Water testing and treatment solutions

• Clear documentation for audits

• Expert guidance tailored to your building

  
  

If you’re unsure whether your building is compliant, the safest next step is a professional assessment.

Get peace of mind and protect your occupants.

Contact us today to schedule your Legionella risk assessment or speak with an expert.

Final Thoughts

Preventing Legionella isn’t just about ticking boxes—it’s about protecting people, staying compliant, and avoiding costly mistakes.

With the right plan in place, you can confidently manage your risk and keep your building safe.