New Insights into the Management and Design of Water Systems to Prevent Healthcare-Associated Infections
- 6 hours ago
- 3 min read
By Professor Harriet Whiley
Environmental Health, Flinders University
ARC Training Centre for Biofilm Research and Innovation
Water: An Overlooked Risk in Infection Prevention
It is well accepted that healthcare-associated infections (HAIs) present one of the most significant threats to patient safety within hospitals. However, what remains critically underacknowledged is the role of water systems in facilitating these infections. While hand hygiene and surface disinfection are rightly emphasised, water is frequently overlooked in infection control protocols, despite its documented role in outbreaks linked to pathogens such as Legionella, Pseudomonas aeruginosa, and Acinetobacter baumannii.
Our recent studies have explored this risk in greater detail, shedding light on the microbiological complexity of biofilms found in hospital plumbing, and identifying mechanisms by which these pathogens spread, particularly through aerosolisation from handbasin drains and retrograde contamination of faucets. This work calls for a fundamental rethink in how we design and manage water systems within healthcare environments.
Biofilms and the Plumbing Niche: A Perfect Storm
Hospital plumbing provides a near-perfect niche for microbial survival and proliferation. Within the protective matrix of biofilms (those slimy microbial communities adhering to surfaces) bacteria are shielded from heat, disinfection, and even antibiotics. In this environment, both waterborne pathogens (Legionella, Mycobacteria) and non-waterborne contaminants (Staphylococcus aureus) thrive.
Alarmingly, our research has identified Staphylococcus aureus, including methicillin-resistant strains (MRSA), in handbasin drains and outlets. This is not a waterborne pathogen and therefore likely to originate from patient and staff hands. Its presence in the plumbing system indicates that hand hygiene activities themselves may be contributing to microbial colonisation of the water system. This represents a troubling feedback loop: the very act of handwashing potentially contaminating the infrastructure meant to protect us.
Antimicrobial Resistance: Plumbing as a Reservoir
Beyond the immediate infection risks posed by these pathogens, we have also identified several antimicrobial-resistant organisms within hospital plumbing biofilms. These include MRSA, carbapenem-resistant Pseudomonas aeruginosa, and Acinetobacter baumannii. The co-location of these organisms within biofilms facilitates horizontal gene transfer, providing ideal conditions for the amplification of antimicrobial resistance (AMR).
In light of Australia’s growing concern around AMR, this finding has profound implications. It positions water infrastructure not just as a passive conduit, but as an active reservoir and incubator for resistant organisms. Yet, this reality is still not reflected in most infection control guidelines or building standards.
Understanding Microbial Mobility: From Drain to Faucet
Using a laboratory model of a hospital handbasin, our team has demonstrated how aerosols and droplets can facilitate the transfer of bacteria from drains to faucet aerators, especially under certain flow conditions. We tested various faucet flow restrictors and observed striking differences in droplet dispersion and aerosol formation. Some configurations significantly reduced splashback, while others exacerbated contamination risk.
This mechanism offers an explanation for how pathogens can be aerosolised and deposited onto nearby surfaces, medical equipment, or even directly into the hands of healthcare workers, turning the sink into a source of cross-contamination rather than protection.
Conclusion: Designing for Water Safety to Prevent Infection
Water is an important but often overlooked source of healthcare-associated infections. Opportunistic waterborne pathogens are always present at low concentrations, but in high-risk environments like hospitals, their amplification and spread can have serious consequences. Our research reinforces the urgent need to treat plumbing infrastructure as a critical infection control frontier.
To do this effectively, we must embed microbial risk management into every stage of water system design and maintenance. Key control factors include hydraulic management to prevent stagnation, maintaining water temperatures outside the typical microbial growth range (25–43°C), ensuring disinfectant residuals, limiting available nutrients, selecting plumbing materials that minimise microbial colonisation, and controlling aerosol generation.
Incorporating these principles into healthcare engineering standards will allow us to build water systems that are not just functional, but safe. By recognising the microbial realities of water infrastructure and applying a proactive, design-informed approach, we can reduce the burden of HAIs.
Harriet Whiley is a Professor in Environmental Health. As an environmental microbiologist and accredited Environmental Health Officer her research is aimed at informing best practice control of pathogens to protect human health. She is passionate about collaborative research with industry and government partners to facilitate the feedback loop between research, regulation, and practice. Her research areas include infection control, biofilms, water quality, food safety and risk assessment.
Join us at the upcoming IHEA National Conference to hear Dr Harriet Whiley speak further on the topic at 3:40 PM on Tuesday May 27 - Day Two of the IHEA National Conference.