Majority of potable water microplastics are smaller than the 20 µm EU methodology limit for consumable water quality

Microplastic (MP) content in nutrition including potable water is unregulated, although MP concentrations in bottled water can diverge by several orders of magnitude. The EU Directive 2020/2184 on consumable water quality recently proposed methodological approaches to the detection of MPs in potable water in the size range of 20-5000 µm. However, small MPs in the 1-20 µm range are far more likely to pass the human intestine into blood and organs. We therefore investigated MP concentrations down to 1 µm in ten individual polyethylene terephthalate (PET) bottled water brands and one tap water sample by Raman microspectroscopy. Our analyses are supported by procedural blank- (negative control) and analytical recovery correction (positive control) using red polyethylene fragments in the 5-100 µm range. We find that MP concentrations range from 19 to 1,154 (n/L) [0.001 to 0.250 µg/L]. Importantly, 98 and 94% of MPs measured less than 20 and 10 µm in diameter, respectively, demonstrating the importance of small MP inclusion in potable water analyses and regulation.