Temperature-dependent microbial dynamics in touchless sensor faucets during short-term stagnation

Area of Science:

• Environmental microbiology
• Public health
• Building water systems

Background:

• Microbial contamination in plumbing poses health risks.
• Short-term stagnation in touchless faucets is poorly understood.
• Faucet design impacts microbial regrowth.

Purpose of the Study:

• Investigate microbial water quality changes in touchless faucets during short-term stagnation.
• Determine the effect of temperature on microbial regrowth and specific pathogens.
• Establish safe stagnation periods for touchless faucets.

Main Methods:

• Simulated short-term stagnation (0.25-10 hours) at different temperatures (10, 30, 40 °C).
• Monitored microbial diversity, Legionella pneumophila concentrations, and adenosine triphosphate (ATP) as a biomass indicator.
• Analyzed chlorine decay and biofilm contributions.

Main Results:

• Microbial diversity decreased and L. pneumophila increased significantly between 2-4 hours of stagnation.
• 30 °C maximized microbial biomass but minimized L. pneumophila, while 40 °C reduced biomass but promoted L. pneumophila growth.
• Accelerated chlorine decay and biofilm influenced microbial changes.

Conclusions:

• A temperature-dependent safe stagnation period of 2-4 hours was identified for touchless faucets.
• Flushing is necessary after 2-4 hours to mitigate health risks.
• Optimizing faucet temperatures (30-40 °C) can balance safety, comfort, and energy efficiency.