It’s a sign that a topic is going mainstream when it becomes cited in the model codes. Unfortunately, Legionella prevention has broken that barrier during this cycle due to increased hospitalizations and deaths. It has taken years to be mentioned in the model codes, but there finally appears to be some movement to address the issue.
Since the early days, the Uniform Plumbing Code (UPC) and International Plumbing Code (IPC) have required the disinfection of new potable water systems, or as required by the authority having jurisdiction (AHJ). If the AHJ does not have a method prescribed, the method is to: