Chapter 2: Legionella risk and hazard assessment
From: Public Services and Procurement Canada
2.1 General
- 2.1.1 Each Legionella susceptible system identified in the Legionella Bacteria Control Management Program (LBCMP) shall have its Legionella level of risk identified and documented.
- 2.1.2 Each facility shall have its Legionella level of risk identified and documented.
2.2 System risk assessment
2.2.1 The system Legionella risk level shall be identified as low, medium, or high based on the presence of Legionella hazard characteristics specific to that type of system. Table 2.1 below provides a guideline that may be used to identify the system risk level based on the system's Legionella hazard characteristics that may be present; it is only illustrative. Other industry Legionella guidelines and standards may be consulted to identify specific Legionella hazard characteristics that may not be identified in Table 2.1.
| System type | Hazard characteristics | Risk level |
|---|---|---|
| Cooling tower | No evaporative condenser | Low |
| Located more than 10 m from air intake | Low | |
| Located less than 10 m from air intake | High | |
| Excessive drift from tower exhaust | High | |
| Water temperature always below 20 °C at any point in the system | Low | |
| Water temperature in 20-35 °C range at any point in the system | Medium | |
| Water temperature exceeds 35 °C at any point in the system | High | |
| Located within 10 m of kitchen exhausts, vegetation etc. | High | |
| Recent history of elevated bacterial levels | High | |
| Open water systems | Water temperature always below 20 °C at any point in the system | Low |
| Water temperature in 20-35 °C range at any point in the system | Medium | |
| Water temperature exceeds 35 °C at any point in the system | High | |
| Aerosolization of water occurs | High | |
| Located within 10 m of kitchen exhausts, vegetation etc. | High | |
| Located close to public areas | Medium | |
| Recent history of elevated bacteria levels | High | |
| Humidifiers | Direct steam, infrared or gas humidifier | Low |
| Any other type of humidifier | High | |
| Water stagnation exists | Medium | |
| Drain pans | Water stagnation exists | Medium |
| No water stagnation | Low | |
| Domestic cold water systems | Piping subjected to periods of prolonged water stagnation | Low to medium |
| Water temperature always below 20 °C | Low | |
| Water temperature in 20-35 °C range | Medium | |
| Potential for cross-contamination with process water | High | |
| Piping is not insulated to code | Medium | |
| Shower facilities connected | Medium | |
| Domestic hot water system | Water storage temperature exceeds 60 °C | Low |
| Water storage temperature in 50-60 °C range | Medium | |
| Water storage temperatures below 50 °C | High | |
| Water distribution temperature below 50 °C | High | |
| Piping subjected to periods of prolonged water stagnation | High | |
| No re-circulation pump | High | |
| Shower facilities connected | High |
2.3 Facility risk assessment
2.3.1 The facility Legionella risk level shall be identified as low, medium, or high based on the Legionella risk level of the systems present in the facility, as indicated in Table 2.2.
| System risk level (based on Table 2.1) | Facility risk level |
|---|---|
| Contains any high risk system | High |
| Contains only medium and low risk systems | Medium |
| Contains only low risk systems | Low |