Microplastics hack the water supply system: What it means for water safety and human health?

Water supply systems-spanning from water sources to treatment plants, distribution networks, and ultimately consumers-function as both significant sources and sinks of microplastic pollution. Due to factors such as light exposure, mechanical force of water flow and chemical corrosion by disinfectants, microplastics (MPs) undergo a series of transformations, thereby posing a higher water safety risk. Nevertheless, the distribution of MPs within water supply systems and their potential risks to water safety remain to be fully understood and systematically reviewed. This review provides the first comprehensive synthesis that traces MPs across the entire water supply chain-from source to consumer-to quantitatively link global occurrence, transformation risks, and potential health implications. A comprehensive analysis of MPs abundance in global drinking water sources, tap water, and bottled water from global data (Web of Science Core Collection, up to 2025) revealed a rapidly escalating daily intake of MPs through drinking water, with structural equation modeling identifying the Human Development Index and wastewater treatment rate as key predictors of global microplastic distribution. Beyond occurrence, a cascade of underappreciated risks arising from microplastic persistence and transformation in water supply systems was critically examined-including enhanced disinfection by-product formation, additive leaching, contaminant carrier effects, and human exposure. By integrating evidence on microplastic transformation, aging, leaching, and exposure, this review establishes a conceptual link between microplastic environmental behavior and population-level health implications, offering a mechanistic perspective on risks posed by MPs in water supply systems. The synthesis provides a scientific foundation to guide future research, policy-making, and standard-setting for emerging contaminants in drinking water.