Industrial and Commercial Buildings

Large building water systems vary in their design and their ability for transmitting 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 by water mists that are inhaled into the lungs.

Commercial Building

In 2015, the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) created a standard for risk management in large building water systems, called ANSI/ASHRAE Standard 188-2015 to manage potential risks. This standard includes a Water Management Plan and general requirements for building operators and businesses. To reduce liability, many insurance companies also require businesses to maintain Water Management Plans. After the team is assembled, the building is surveyed to determine whether it has one or more of the following elements:

  • Open- and closed-circuit cooling towers or evaporative condensers that provide cooling and/or refrigeration
  • 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.
  • Multiple housing units with one or more centralized potable water-heater systems.
  • The building is more than 10 stories high (including any levels that are below grade).

Even if buildings do not contain any of the above elements, it is still a good idea to create and implement a water management plan. Water management plans should be continuously maintained and updated. A new plan should be developed every two years or following any changes in these scenarios:

  • any changes to the risk assessment
  • when the building use has changed
  • new information exists about risks or control measures
  • checks indicate that control measures are no longer effective

ASHRAE has also developed Guideline 12-2000, Managing the Risk of Legionellosis Associated with Building Water Systems to help building operators with information and guidance for control of Legionellosis associated with building water systems (ANSI/ASHRAE 2000). The guidance is useful to operators of hotels, office buildings, hospitals and other health care facilities, assisted living facilities, schools, universities, commercial buildings, industrial buildings, and centralized systems in multi-family residential buildings.

The Centers for Disease Control (CDC) has also 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.


Source: Customer Messaging on Opportunistic Pathogens in Plumbing Systems by the Water Research Foundation