Understanding Legionella Risk Assessments: A Guide for Property Owners
- Dec 9, 2025
- 4 min read
Updated: 15 hours ago
What is Legionella and Why is it a Risk?
Legionella bacteria naturally occur in water sources. However, they become dangerous when they multiply in artificial water systems found in homes, businesses, and rental properties. People become infected when they inhale tiny airborne droplets containing the bacteria.
Legionella thrives most easily when:
Water temperatures are between 20 and 45 degrees Celsius.
Water is stagnant or unused for long periods.
There is scale, rust, or sludge in pipework.
Tanks, cylinders, or shower heads are poorly maintained.
The biggest risk areas in both homes and commercial buildings include:
Showers and mixer taps.
Hot and cold water storage tanks.
Unused pipework or dead legs.
Spa baths and whirlpool features.
Cooling towers and commercial water systems.
Legal Responsibilities for Property Owners and Landlords
Legionella control is a legal duty under the Health and Safety at Work Act and the Control of Substances Hazardous to Health regulations. Duty of care applies to any property where water is stored or distributed.
For rental properties, the landlord or managing agent is legally responsible for ensuring the water system is safe. For commercial premises, the duty holder is usually the employer, facilities manager, or building owner.
There is no specific certificate required by law, but evidence of risk control is necessary. The best way to demonstrate this is through a formal Legionella Risk Assessment and proof that any recommended actions have been completed.
Do You Need a Professional Legionella Risk Assessment?
Government guidance confirms that landlords can carry out a Legionella risk check themselves if they are competent and the property is low risk. However, professional assessments are strongly recommended when any of the following apply:
A property contains water tanks rather than a combi boiler.
A property has been vacant for long periods.
Tenants include elderly or medically vulnerable individuals.
Commercial or multi-occupied premises.
Complex plumbing systems or multiple bathrooms.
A professional assessor provides documentation, photographs, and a schedule of actions. This documentation is valuable if there is ever a dispute, insurance claim, or inspection.
How to Reduce Legionella Risk in Residential and Commercial Properties
Here are practical ways to keep water systems safe between assessments:
Keep hot water at 60 degrees Celsius or higher at the boiler.
Keep cold water below 20 degrees Celsius where possible.
Run taps and showers weekly in vacant or rarely used rooms.
Descale and clean shower heads at least every three months.
Insulate tanks and pipework to control heat loss.
Remove unused pipework when possible.
Keep water storage tanks tightly sealed and secure.
Simple routine actions prevent the bacterial growth that leads to Legionnaires' disease.
How Often Should Legionella Risk Be Reviewed?
Most property types follow these industry expectations:
Low-risk residential rentals every 2 years or during tenant change.
HMOs annually.
Commercial premises every 2 years.
High-risk sites such as care homes and gyms annually or sooner if required.
Risk should also be reviewed immediately if there are system changes, water temperature problems, or prolonged vacancy.
Penalties for Non-Compliance
If Legionella controls are ignored and someone becomes ill, the responsible person can face:
Civil claims for injury or death.
Criminal prosecution for negligence.
Invalidated building or landlord insurance.
Enforcement action by the Health and Safety Executive.
Documented evidence of risk management is the strongest defence.
The Importance of Compliance
Legionella control is not just another compliance burden. It protects tenants, employees, and visitors from a serious preventable illness. It also protects property owners from legal and financial consequences. A clear Legionella Risk Assessment paired with simple ongoing checks keeps water systems safe and ensures full compliance with UK regulations.
Conclusion
In summary, ensuring the safety of water systems is crucial for property owners. Regular assessments and adherence to legal responsibilities can prevent serious health risks. By taking proactive measures, we can create a safer environment for everyone involved.
Additional Considerations for Legionella Management
Understanding Legionnaires' Disease
Legionnaires' disease is a severe form of pneumonia caused by Legionella bacteria. Symptoms can include:
Cough
Shortness of breath
Fever
Muscle aches
Headaches
Understanding these symptoms is essential for prompt action and treatment.
Importance of Training
Training staff on Legionella awareness is vital. Regular training sessions can help ensure everyone understands the risks and necessary precautions. Consider the following:
Conduct training on identifying risk factors.
Teach proper maintenance techniques for water systems.
Ensure staff know how to respond to potential outbreaks.
Implementing a Water Safety Plan
Creating a comprehensive water safety plan can streamline Legionella management. This plan should include:
Regular risk assessments.
Maintenance schedules for water systems.
Documentation of all actions taken.
A well-structured plan not only ensures compliance but also enhances safety.
The Role of Technology in Monitoring
Utilising technology can significantly enhance Legionella management. Consider implementing:
Smart sensors to monitor water temperatures.
Automated alerts for stagnant water.
Digital records for easy access to compliance documentation.
These tools can simplify monitoring and ensure timely interventions.
Engaging with Professionals
While self-assessments are possible, engaging with professionals can provide peace of mind. Professionals bring expertise and experience, ensuring thorough assessments and compliance.
Conclusion
Legionella management is a critical aspect of property ownership. By understanding the risks, legal responsibilities, and proactive measures, we can ensure the safety of our water systems. Regular assessments, training, and the implementation of technology will create a safer environment for all.
