Microplastic-affected pathogens in drinking water supply systems: Survival mechanisms, ecological impacts and control challenges

Microplastics (MPs), as emerging pollutants, can affect pathogens, primarily opportunistic pathogens (OPs), and influence their behavior in aquatic environments. However, evidences regarding their impacts in drinking water supply systems (DWSSs) remain scarce. Focusing on the safety of DWSSs, this review synthesizes how MPs affect pathogen proliferation, transport, and resistance development under typical DWSS conditions characterized by low nutrients, high flow rates, oxidative stress, and user demand. MPs can distinctly promote the growth and reproduction of pathogens, act as mobile carriers enabling cross-watershed transport, and facilitate direct migration from source water to humans, thereby increasing health risks. Furthermore, MPs enhance pathogen resistance at both individual and community levels, thereby complicating subsequent control efforts. This study further summarizes how MPs compromise existing pathogen control measures in DWSSs and introduce secondary risks, including MP additives and the disinfection by-products from MPs. Finally, a strategy integrating “pretreatment interception” and “secondary risk reduction” is proposed to control MP-affected pathogens in DWSSs. The review provides valuable insights into mitigating pathogen risks associated with MPs in DWSSs, addressing a significant knowledge gap in safeguarding water security.