Microplastics in drinking water: quantitative analysis of microplastics from source to tap by pyrolysis–gas chromatography-mass spectrometry

The widespread presence of microplastics (MPs) in fresh surface water has raised concerns about potential human exposure through drinking water sourced from these environments. While MP research is advancing to understand the occurrence and fate of MPs in drinking water production systems, data based on mass concentration is scarce. This study assesses MP concentrations in the drinking water supply system of Amsterdam (the Netherlands) from source to tap, analyzing raw water from two freshwater sources (Lek Canal and Bethune Polder), treated water from two drinking water treatment plants (DWTPs) (Leiduin and Weesperkarspel DWTPs), and household tap water samples from the Amsterdam distribution area. MPs ≥ 0.7 µm were identified and quantified using pyrolysis gas chromatography-mass spectrometry (Py-GC-MS) targeting 6 high production volume polymers: polyethylene (PE), polyethylene terephthalate (PET), polymethyl methacrylate (PMMA) polypropylene (PP), polystyrene (PS), and polyvinyl chloride (PVC). Average MP concentrations in raw water samples were 50.6 ± 34.7 µg/L (n = 14) and 47.5 ± 33.7 µg/L (n = 14), while treated water samples exhibited significantly lower levels of 0.80 ± 0.44 µg/L (n = 12) and 1.65 ± 2.19 µg/L (n = 14), demonstrating high removal efficiencies of 97-98%. PE, PVC, and PET were the most abundant polymer types detected. Household tap water samples showed lower concentrations with an average of 0.21 ± 0.12 µg/L (n = 20). These findings highlight the effective removal of MPs during drinking water treatment processes while emphasizing the need for further research to understand the factors influencing MP transport and fate within water distribution networks.