Healthcare Handbasin Design and Microbial Safety: A Review of Guidelines and Current Evidence.

Healthcare-associated infections (HAIs) from waterborne and wastewater-associated pathogens are an increasing public health threat due to rising antimicrobial resistance. Within plumbing systems, microbial water quality and biofilm formation is influenced by interconnected physical, chemical and biological factors. As an integrated water-wastewater system, healthcare handbasins can become contaminated with pathogens from incoming water, wastewater plumbing, or during handwashing. Contaminated fixtures are an infection risk, particularly for immunocompromised individuals, with exposure occurring through ingestion, inhalation, aspiration and direct or indirect skin contact with water or aerosols. Handbasin design influences biofilm formation and bacterial transmission via splashing and aerosol generation, impacting infection risks. This review examines international healthcare handbasin design guidelines against scientific evidence to identify areas of alignment and divergence. Across the thirty-nine countries reviewed, infection control design guidelines varied considerably. Eight countries considered basin shape to improve drainage and minimise splashing. Offset drain positioning was a key design consideration for infection control, which was identified to reduce splashing and pathogen dispersal across the literature. Aerosolization and biofilm-related design risks were often addressed, however, inconsistent recommendations on outlet fittings, outlet flow rates and faucet operation reflected competing priorities between infection control, user safety, and water efficiency. This inconsistent consideration of design for infection control highlights a disconnect between policy and evidence. Further research is needed to understand how design features and operational conditions influence infection risk. Future designs must balance biofilm control, splashing and aerosol reduction, support for clinical handwashing techniques, water efficiency and scald prevention to protect patients and reduce HAIs.