Could slow water flow be risky when handwashing?

The speed at which water flows from hand basin taps can influence infection spread in aged care and hospital settings, new research has found.

Production of bioaerosols — or airborne water particles that may contain bacteria or viruses — poses a significant public health concern, environmental health experts from Flinders University have warned.

“This research highlights an often-overlooked factor in infection control, raising the potential for more infection control in healthcare settings and public spaces,” said Flinders adjunct academic Dr Claire Hayward, who is now a postdoctoral researcher working on antimicrobial resistance in the community. She is also the lead author of a new article in the Building and Environment journal.

“In hospitals and aged care facilities, bioaerosols generated from handwashing basins have been linked to healthcare-associated infection outbreaks,” Hayward said.

“However, there has been limited research on how basin design parameters, such as flow rate restrictors, impact bioaerosol production and transmission routes.”

How fast should water flow?

The findings in the latest study showed that all three flow restrictors tested produced respirable-sized bioaerosols. While there was no significant difference in the number of aerosols and droplets originating from the source water across different flow rates, lower flow rates led to an increased generation of aerosols from the drain and greater retrograde contamination from the drain to the faucet.

This suggests that while reducing water flow may help with water conservation, it could inadvertently increase the spread of potentially harmful microbes.

The senior author in the study, Flinders University Professor Harriet Whiley, said: “These results highlight the complex relationship between plumbing design and infection control. By optimising design elements like aerators and flow rates, we may be able to reduce infection risks, but further research is needed to identify the safest and most effective configurations.

“The study underscores the importance of collaboration between product designers, engineers and microbiologists to develop hand basin designs that balance functionality with infection prevention.”

As bioaerosol transmission continues to be a concern in high-risk environments, these insights could inform future plumbing innovations and healthcare policies, researchers conclude.

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