Fortunately, there are few microplastics in drinking water from groundwater sources. Mintenig and his colleagues [85] analyzed the occurrence of microplastics in the groundwater source and in the drinking water obtained from it. The samples were collected from different points of the drinking water supply, the samples were filtered (through a 3 μm filter) and particles above 20 μm were analyzed by FTIR spectroscopy. Both fibers and particles were found in the blank sample (0.67 particles/L, 0.3 fibers/L), indicating that these can also enter the filter unit during sample processing, which were excluded from the analysis. The average microplastic concentration was 0.0007 particles/L, varying between 0 and 0.007 particles/L in both raw water and drinking water. Regarding their material quality, the particles were identified as PE, PA, PEST, PVC or epoxy resin, and their size ranged from 50 to 150 µm. According to the authors, the plastic particles detected in the water samples probably come from the wear and tear of plastic equipment used in water treatment or transportation.

Significantly larger amounts were reported [86] for the microplastic content of the raw and treated water from surface sources of three drinking water providers in the Czech Republic (Drinking Water Treatment Plants [DWTP]). Samples were sequentially filtered through 5 and 0.2 µm membrane filters and oxidized with peroxide. Sections of the filters were analyzed by electron microscopy to determine the number, shape, and size of the particles. Particles larger than 10 µm were characterized by FTIR and particles larger than 1 µm were characterized by Raman spectroscopy. The amount of microplastic pollution in all water samples was in the range of 1473-3605 particles/L and in the range of 338–628 particles/L in treated drinking water. The background contamination determined by blank filter analysis was negligible, less than 5%. A typical removal efficiency of 70-80% was found during drinking water treatment. Contamination by microplastics smaller than 10 μm dominated in both raw and treated water samples, accounting for up to 95% of the particles found. In terms of the material quality of the microplastic particles, 12 different materials were identified, but the majority of the contamination (70%) consisted of PET, PP, and PE.