Utilizing UV LED Disinfection to Decrease Pseudomonas aeruginosa Biofilm Formation in Drinking Water Systems

Opportunistic pathogens (OPs), such as Pseudomonas aeruginosa , can form biofilms and proliferate in drinking water distribution systems (DWDS) and building premise plumbing even in the presence of a disinfectant residual and are responsible for the largest number of deaths attributable to waterborne disease in the United States. There is a need for strategies to prevent biofilm formation and therefore the sustained occurrence of OPs throughout DWDS. This study demonstrates how UV LED disinfection (282 nm, 50 mJ/cm 2 ) before entering a distribution system or at a building's point‐of‐entry can delay the start of detectable biofilm formation for up to 6 days and significantly reduce the concentration of biofilm‐bound cells for up to and beyond 8 days compared to untreated controls. Biofilm growth after UV LED disinfection was evaluated on different materials (PTFE, CPVC, and Cu) and under different carbon nutrient conditions (19 mg/L TOC, 100 μg/L C, 250 μg/L C). PTFE supported the highest biofilm growth, followed by CPVC, while Cu supported the least. UV pre‐treatment reduced downstream biofilm formation by 0.33–2.42 log CFU/coupon (53.0%–99.6%) on CPVC surfaces over 5–8 days, with more realistic drinking water carbon conditions (100 or 250 μg/L C) increasing efficacy compared to heightened carbon conditions (19 mg/L TOC). These results inform how UV LEDs could be implemented within drinking water infrastructure to aid in biofilm and OP control.