Microplastics in drinking water distribution systems: Occurrence, environmental behavior, and human health concerns

Microplastics, increasingly detected in drinking water, have sparked growing concern due to their persistence, potential bioaccumulation, and risks to human health. Elucidating their fate in drinking water distribution systems (DWDSs) is critical for accurately assessing exposure risks and guiding effective mitigation strategies. This review systematically evaluates the microplastic occurrence at key nodes in DWDSs, their morphological characteristics, and environmental behaviors within the network. Direct comparisons across studies are hindered by methodological inconsistencies, highlighting the need for standardized protocols. Drinking water treatment plants serve vital function limiting microplastics ingress into the distribution systems, but conventional technologies often fail to ensure complete removal. Microplastics are predominantly present as small and fibrous particles within DWDSs. The wear and degradation of plastic pipes and fittings are recognized as potential sources of microplastic contamination. Neglected small microplastics and nanoplastics tend to exhibit colloidal properties that enhance their mobility and sorption potential. Microplastics exhibit complex environmental behaviors during transport. Due to their diminutive size and high specific surface area, microplastics act as effective vectors for microbial colonization and co-pollutant accumulation, thereby intensifying the composite contamination risk. Furthermore, the irregular structure and high porosity of the pipe scale facilitate microplastic retention and adsorption. This review reveals the distribution and fate of microplastics in DWDSs, offering scientific references for developing effective pollution control strategies for microplastics.