ASPE experts offer engineering methodologies to reduce the risk of Legionella in plumbing systems

Posted by Johann Nacario — June 9, 2023 — The American Society of Plumbing Engineers (ASPE) recently announced that its Engineering Methodologies to Reduce the Risk of Legionella in Premise Plumbing Systems guide is now available.

Ramiro Mata, ASPE’s senior director of Technical and Regulatory Affairs, stated:

With increasing Legionnaires’ disease outbreaks, many organizations have written guidelines and standards to mitigate its occurrence. However, this is the first comprehensive guide that incorporates the latest tools, methodologies, and best practices for design professionals to minimize disease and injury from Legionella pneumophila bacteria related to building water systems.

ASPE guide to reduce risk of Legionella in plumbingTo develop this guide, ASPE assembled a Working Group consisting of ASPE members actively engaged in the use of Legionella mitigation techniques as well as practitioners involved with rectifying outbreaks. Over the past four years, the Working Group used information from existing papers, research documents, and input from ASPE members and the general public to craft the guideline.

Working Group Chair Christoph Lohr, PE, commented:

I am very excited to see the completion and publication of this important document. I was honored that ASPE asked me to chair this Working Group four years ago, and I’m very thankful for the wonderful group of dedicated volunteers who worked tirelessly to complete this design guide. Since 2015, more and more plumbing design professionals have been asking for practical and actionable design steps in reducing the risk of Legionella. With the release of ASPE’s Engineering Methodologies to Reduce the Risk of Legionella in Premise Plumbing Systems, plumbing engineers and designers have that information at their fingertips.


Contributing Factors for Legionella Growth and Transmission
Inter-relation of Contributing Factors
Plumbing System Components and Spectrum of Results
Water Quality
Domestic Cold Water System Design
Hot Water System Design
Scale Inhibition
Plumbing Fixtures
Aerating Equipment
Water Management Program
Combining Design Methodologies
Appendix A: Hot Water Recirculation Design and Sizing
Appendix B: Flushing Time
Appendix C: Legal Considerations
Appendix D: Pressure Zone Design
Appendix E: Water Quality
Appendix F: Design Approach

ASPE intends for this guide to be periodically updated to provide the latest innovations in Legionella and waterborne pathogen mitigation in building water systems, and invites participation from all stakeholders.

Engineering Methodologies to Reduce the Risk of Legionella in Premise Plumbing Systems is available for purchase in the ASPE Bookstore.