Industrial/ Commercial


Large building water systems vary in their design and capability for transmission of Legionella, however the factors that can lead to a Legionella outbreak remain the same. Bacteria must still be transmitted to susceptible people in the building through the generation of aerosols and must be inhaled or aspirated into the lungs. In 2015, the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) created a standard for risk management in large building water systems (ANSI/ASHRAE Standard 188-2015) to manage potential risks.This standard includes the compliance and general requirements for building operator and businesses. To reduce liability, many insurance companies also require businesses to maintain water management plans.

ANSI/ASHRAE Standard 188-2015 building water safety plan consists of seven elements shown in Figure 1. After the team is assembled, the building is surveyed to determine whether it has one or more of the following elements:
  1. Open- and closed-circuit cooling towers or evaporative condensers that provide cooling and/or refrigeration
  2. Whirlpools or spas, either in the building or on the site; or ornamental fountains, misters, atomizers, air washes, humidifiers, or other non-potable water systems or devices that release water aerosols in the building or on the site.
  3. Includes multiple housing units with one or more centralized potable water-heater systems.
  4. It is more than 10 stories high (including any levels that are below grade).

The ANSI/ASHRAE Standard 188-2015 also pertains to hospitals, healthcare facilities and nursing homes.Details for these systems is found on the Hospitals/Healthcare Facility page. Even if buildings do not contain any of the above elements,a water management plan should be developed.

The Center for Disease Control, CDC, has created a toolkit for large buildings to ensure the safety of staff and the public. The CDC toolkit can help identify areas of concern where Legionella might grow and be transmitted. The toolkit includes practical resources to help ensure a comprehensive and effective system that holds to industry standards.

Water management plans should be continuously maintained and updated. A new management plan should be developed when more than 2 years have elapsed since the last risk assessment, the building use has changed, new information exists about risks or control measures, checks indicate that control measures are no longer effective, or if a case of Legionnaires' disease is associated with the system.