Premise Plumbing Systems - Legionella and other opportunistic pathogens

Session 1.1

Are we Oversizing Water Services in Australian Healthcare Buildings?

Deakin University researchers will present their findings from water consumption data collected at several Australian Hospitals. Data analysis considers overall water consumption and peak demand for cold and heated water services in Australian hospitals.

These results are compared to established design practices, code and standards. Results identify that there is a large gap between monitored and design demands. This highlights opportunities to lower construction costs, reduce energy consumption and improve water quality.

Work previously conducted by Deakin University and the Hydraulic Consultant Association of Australasia (HCAA) has identified that the current formula within AS3500 significantly over-estimate the peak water demand, leading to oversized plumbing systems in residential buildings (https://www.waterdemand.com.au/results). Building on this work, the project has now moved into monitoring healthcare buildings across Australia.

Currently, the peak demand formula in AS3500 is predominantly for the design of residential buildings and anecdotally has little transference to the design of hospitals. This forces hydraulic designers to opt for a performance solution pathway and implement peak demand formulas from international plumbing codes and standards that provide guidance towards healthcare design. However, initial investigations are beginning to highlight both the formulas outlined in AS3500 and the international hospital-specific peak demand formula are significantly larger than monitored water demands. This means that the oversizing problem is not just limited to residential buildings, and may exist in the healthcare space.

This suggests similar opportunities for improved design and operation of water services can be realised.

The session will cover the following topics:

Presentation of data and results for water use in Australian healthcare buildings:

• Discuss the implications of oversizing water services with respect to:

• Cost

• Energy use

• Water quality

•Water conservation

• Discuss potential unintended consequences of future water service design with smaller components
• Identify future research needs to improve healthcare water service design

Session 1.2

Efficacy of chlorine-based disinfectants to control Legionella within premise plumbing systems

Legionella is a naturally occurring waterborne bacterium that can cause Legionnaires’ disease, a severe and sometimes fatal pneumonia-like infection. In healthcare settings, where vulnerable populations are most at risk, contaminated showers and taps can unknowingly spread this pathogen through aerosols and mist.

Total eradication of Legionella in potable water is not feasible, which makes effective water management strategies essential. Chlorine-based disinfection—using chlorine, monochloramine, or chlorine dioxide—has been a trusted solution for nearly a century. However, its effectiveness varies across different buildings and system designs due to a complex mix of temperature, flow, biofilm, and pipe materials.

This session offers a systematic review of the key factors that influence disinfectant performance and decay. Attendees will gain actionable insights to improve Legionella control, protect public health, and support safer water systems in healthcare facilities.

Session 2.1

Beyond Legionella: What Else Is Lurking in Our Pipes?

While Legionella is well-known in the world of waterborne pathogens, it’s far from the only microbial threat in our plumbing systems. This talk explores the broader category of opportunistic premise plumbing pathogens (OPPPs), including Pseudomonas aeruginosa, non-tuberculous mycobacteria, and antimicrobial-resistant strains increasingly linked to healthcare-associated infections. Drawing on recent research, including bioaerosol production from handwashing basins and contamination risks from low-flow fixtures, we’ll examine how design choices and water management practices shape microbial risks in residential and healthcare settings.

Attendees will gain insight into the hidden microbial ecosystems that thrive in pipework, faucets, and drains, and how stagnation, temperature, materials, and flow dynamics influence their proliferation and transmission. Emphasis will be placed on why we must shift from routine pathogen testing toward proactive system design and management to reduce risk. It’s time to look beyond Legionella — because our plumbing systems harbour much more than we think.

Session 2.2

Plumbing and Infection Control – How clean are your tools?

An overview of the infection control and hygiene issues in healthcare that can be caused by a lack of hygiene and cleaning of plumbing equipment, and how they can be prevented.