In late May, ASHRAE updated its guideline on the control of legionellosis associated with building water systems. The updated document, ASHRAE Guideline 12-2020, is intended to help building owners and others involved in the care of centralized building water systems manage the risk of legionellosis associated with those systems.  ASHRAE notes that Guideline 12 can be useful in the implementation of ANSI/ASHRAE Standard 188, which establishes minimum legionellosis risk management requirements for building water systems. A preview of Guideline 12-2020 is available on ASHRAE’s website.