WHITE PAPER

Legionella and Beyond:

The Complex Interplay Between Water Hygiene and Corrosion in Healthcare Building Systems
Legionella--and-Beyond

This paper explores the often overlooked yet critical relationship between water hygiene and corrosion within healthcare building systems.

Authored by:
Dr Surani McCaw | Tom Wise

About the white paper

This white paper explores the complex and often overlooked relationship between water hygiene and corrosion within healthcare building systems. It challenges the continued reliance on outdated chemical indices like the Langelier Saturation Index (LSI), and presents a more realistic picture of how microbial risks, flawed system design, and mechanical stressors interact in real-world environments.

Drawing on engineering expertise and practical experience, the paper outlines critical failure patterns and highlights where traditional approaches fall short — providing a clearer path forward for improving infrastructure reliability, safety, and compliance.

  • Why indices fail: Learn why the Langelier Saturation Index (LSI) doesn’t capture real-world system stressors

  • Key failure modes: Microbiologically Influenced Corrosion (MIC), erosion corrosion, and the risks of over-chlorination

  • Biofilm risks: Understand the limitations of disinfection methods and why it isn’t always effective

  • Woolies Law: A new lens for understanding how minor issues compound and interact

  • Actionable insights: Practical recommendations for improving system design, operation, and maintenance

 

About the authors

Surani re-sized

Dr Surani McCaw is a Chemical Engineer with over 25 years of industrial experience, specialising in water treatment in the Healthcare and Pharmaceutical Industries. Surani holds a Bachelor of Engineering (Chemical) degree and a Doctor of Philosophy degree in water treatment from the University of NSW, Kensington, NSW.

Dr McCaw has been involved in the implementation of National Healthcare Standards/Practices for both CSSD and Renal Dialysis since 2008 with the intention of evaluating and implementing risk managed and cost-effective water treatment technologies that are fit for the Australian ecological and demographical environment.
Tom Wise WEB04 (1)

Tom Wise is a healthcare designer specialising hydraulic services, with a focus on water services design for both drinking and hygiene purposes. Tom holds a building services qualification from the University of Sydney, NSW, along with a diploma in engineering.

Tom has been involved in over 100 healthcare engagement, including water hygiene advisory. Tom serves as the technical lead for the Australian Building Codes Plumbing Code of Australia Technical Reference Group, as well as the technical lead for the 815 Water Supply Standard for the International Code Council. Additionally, Tom assists with the development of the AusHFG suite and is a part author/contributor of some of the State and Territory healthcare engineering guidelines.