"This session will provide a comprehensive exploration of how domestic hot water system design impacts Legionella risk, with a focused examination of the role flow-through expansion tanks play in maintaining safe, high-performance building water systems. You will learn the environmental and operational factors that allow Legionella to thrive, including water stagnation,
Register at expo.aspe.org temperature ranges, biofilm development, and system oversizing. The session will introduce multi-port flow-through expansion tanks and explain how their engineered internal flow path, continuous circulation, and separation of inlet and outlet points help eliminate the stagnant conditions associated with traditional single-port tanks. It will also review key regulatory and industry drivers—including ASHRAE 188, CDC guidance, and state-level requirements—that shape modern best practices in potable hot water design. Additional topics will include temperature management, tank sizing, flow rate considerations, and practical piping strategies such as parallel tank arrangements. By the end of the session, you will understand how proper equipment selection and thoughtful system layout improve water safety, reduce bacterial risk, and support compliance across a wide range of commercial building applications."