Transport, Behavior, and Human Exposure of Microplastics in Rural Drinking Water Supply Chains

Despite growing concerns about microplastic contamination in urban drinking water, the transport and fate of microplastics within large-scale rural drinking water supply chains remain poorly understood. This study investigated the distribution, migration, and risk of microplastics in source water (lakes, reservoirs, and rivers), drinking water (tap water and well water), and water treatment plant (WTP) across 15 rural regions in Southwest China. Microplastics were ubiquitously detected in all of the samples. Three risk models demonstrated a significantly lower microplastic risk in tap water relative to source water, while well water posed the highest risk. In five regions, microplastic abundance increased and polymer types diversified from the source to tap water, suggesting microplastic release from the water distribution system. Coagulation-sedimentation and ultrafiltration in the WTP removed 65.9% and 100% of the microplastics, respectively. However, backwashing led to the release of the retained microplastics. Correlation, regression, and principal component analyses revealed that the TOC and turbidity were the key factors associated with microplastic abundance. Five metal ions exhibited removal patterns similar to those of microplastics in water treatment. Rural residents may ingest 913 microplastic particles annually by consuming 1 L of tap water every day. This study provides valuable insights into the fate of microplastics in rural drinking water.