Application of GCMS-pyrolysis to estimate the levels of microplastics in a drinking water supply system

Communities value water and aquatic environments for a many diverse reasons. Ensuring safe drinking water is prioritized on the political agenda with a dedicated focus on safe and affordable drinking water under the 6th of the UN sustainable development goals. The occurrence of micron sized plastic fragments has been confirmed even in very remote areas. In the present study we analysed drinking water of a medium-sized Norwegian urban area for the presence of microplastics ≥ 1 µm. A modular filtering sampling devices was developed allowing a sequential in-situ enzymatic and mild oxidizing driven sample preparation prior to pyrolysis gas chromatography-mass spectrometry sample's analysis (pyr-GCMS). Samples were taken at different stages of the drinking water supply chain. The total amount of polymers per sites ranged from 6.1 to 93.1 µg/m³. Higher levels were detected in the raw water, but significant reduction rates ranging from 43% to 100% depending on the polymer type were scored after the water treatment processes. Polyethylene, polyamide, and polyester were the most frequently detected polymer types. Overall, the levels of MPs in the raw water influence the occurrence and polymer type occurrence and distribution is the drinking water supply net. This study contributes to the emerging field of plastics pollution in drinking water supply systems by providing effective methods helping with future routine monitoring of this source of human plastic uptake.