1. Session 8: Risk Assessments and Water Systems
Facilitator notes:
Legionnaires’ disease: Risk assessment, outbreak investigation and control
Session 8: Risk Assessments and Water Systems
ECDC, 2011

5. What is Risk Assessment?
A method of identifying hazards and risks in an activity, workplace or other setting
It generally involves control measures
The control measures invariably are there to protect employees, the general public and other people
Prepared by competent people, often written and must be reviewed

6. What is Risk Assessment - for the control of Legionella in water systems?
A method of identifying hazards – such as the biological hazard of Legionella pneumophila
A system for assessing risks of these biological hazards – with due consideration of the environmental exposures and the risk of disease
Involves identifying control measures
Prepared by competent people, often written and must be reviewed – often referred to as; a water safety plan

7. Environmental Exposure and Disease
No established dose-response relationship for Legionella infections
Transmission may occur through inhalation, aspiration or directly from contaminated water
Other sources of Legionella bacteria have been identified/linked to cases/cluster and outbreaks
Clinical microbiology is often insufficient to link to the source and environmental samples
Do we miss cases?

8. Targets for Public Health
What target should we set for cases of Legionnaires disease?
What are the risks within water/aerosols?
What is safe?
What is acceptable?
Who should set the targets - for levels in water systems?

9. Environmental Targets - the Issues
Clinical/culture based methods are based on the isolation of Legionella pneumophila Sg1
Limitations of Environmental samples – for verification of control and during outbreaks/incidents
Susceptibility to infection varies
Risks linked to particular aerosols varies
Develop a plan for management

10. Legionella Management Planning
Water safety plans/risk assessment plans
Assessment – risk based, prioritising hazards and risks in the system
Premises specific
Monitoring –
Management –
Communication -
Review

11. Who is in the team?
Assemble a team
And how?
Document what?
Document the system
And risks!
What hazards?
Assess hazards
How do we assess?
Assess the system
What
are the controls?
Identify controls
Monitor controls
Validate controls
What is the support system?
Develop support system
Prepare management procedures
Documentation and Communication
Record, audit and review

12. Assembling the team Document the system
Individuals with an understanding of the water systems – it’s design and operation
an understanding of the ecological factors that encourage Legionella growth
A multidisciplinary team will be required for complex settings
External expertise may be required to support
Document the system
List the water systems that may be present

13. Identify possible control points and controls
Identifying layout and design - schematics
Document the system
Assess hazards
Flow charts – assist in the understanding characteristics of the water system
Assess the system
Identify pathways – by which legionellae can be transferred to consumers
Identify risk points in the water system
Identify possible control points and controls

14. Consider seasonal variations Employ expert assistance
Assess all of the hazards
Assess the system
Hot roofs spaces/roof voids
Over sized water storage tanks
Poorly insulated pipes
Consider seasonal variations
Employ expert assistance

15. Control – temperature of water
Controls and control points
Control – design of system, including low flow areas
Control – potential media /surfaces for growth of the organism
Control – nutrients eg organic matter and sediments
Control – temperature of water
Premises specific assessments and controls
All systems, areas, outlets, sources of hazard – and potential risk

16. Control – using temperature
Other control mechanisms/systems ………

17. Controls – advantages and disadvantages of control methods in water systems
Cold supply
Hot hold
Hot flush
Hypochlorite
Monochloramine
Chlorine dioxide

18. Controls – advantages and disadvantages of control methods in water systems
H-Peroxide
Cu Ag
oxidation
U/V
Filtration
Filters
Hot and heat
Biocides

19. Who is in the team?
Assemble a team
And how?
Document what?
Document the system
And risks!
What hazards?
Assess hazards
How do we assess?
Assess the system
What
are the controls?
Identify controls
Monitor controls
Validate controls
What is the support system?
Develop support system
Prepare management procedures
Documentation and Communication
Record, audit and review

20. Controls – identify sampling points, for monitoring and verification of control

21. Controls – identify sampling points, for monitoring and verification of control

22. Management procedures
Support system
Training – and competencies
Recording and gathering reflective data
Developing verification protocols
Management procedures
Actions – in response to failures
Actions – in response to incidents
Role and responsibilities identified
Document the system
Communication

23. Communication
Identify personnel involved in;
Developing and identifying control measures
Maintaining controls
Managing the water safety plan
Clear statements of responsibilities – to ensure cooperation and robust actions/response

24. Communication
Targets/controls and monitoring points
List of required maintenance records
Verification data – sampling and results
Routine maintenance – action list
Description and assessment of the water system – including a current schematic
Training records etc
Procedures – for normal operation and incidents

25. Risk Assessment and Water Safety Plans
Not about the safety of staff – health and safety
But - the control of legionella in the water system

26. Questions

27. Facilitator notes:
Acknowledgements The creation of this training material was commissioned in 2010 by ECDC to Health Protection Agency (UK) and the University of Chester (UK) with the direct involvement of Louise Brown, Janice Gidman, Emma Gilgunn-Jones, Ian Hall (on behalf of the ECDC Legionnaires Disease Outbreak Toolbox Development Group), Tim Harrison, Rob Johnston, Carol Joseph, Sandra Lai, John Lee, Falguni Naik, Nick Phin, Michelle Rivett, and Susanne Surman-Lee. The revision and update of this training material was commissioned in 2017 by ECDC to Transmissible (NL) with the direct involvement of Arnold Bosman and Kassiani Mellou.