Legionnaires’ disease, first identified in 1976, is caused by water contaminated with Legionella pneumophilia which, when disseminated in droplets into the atmosphere and inhaled, may infect a person. The interest and concern in Legionella management and control within building water and air systems has continued to grow as Legionella outbreaks increase. Although plumbing systems are a common source of such outbreaks, mechanical systems such as cooling towers, air distribution systems, spas, fountains and hot water tanks can also act as breeding grounds for the bacteria that causes Legionnaires' disease.
During the 2024 edition of the Uniform Mechanical Code (UMC) code cycle, the UMC Technical Committee formed a task group to address Legionella in mechanical systems for the UMC. Prior to the formation of this group, the Uniform Plumbing Code (UPC) Technical Committee formed a task group for the 2021 edition of the UPC, which resulted in the creation of a new Appendix N, “Impact of Water Temperature on the Potential for Scalding and Legionella Growth.” The Uniform Codes published by IAPMO consistently endeavor to integrate major health and safety concerns, earning the reputation of being all-inclusive safety codes in an ever-changing environment. The UMC is developed via an ANSI-approved development process, which ensures consensus and due process in its development.