Abstract Microplastics (MPs) are emerging contaminants of concern in aquatic ecosystems. Up to now, only a few studies about MP contamination in drinking water have been published. In this study, we analysed drinking water originating from ground water, surface water and treated sewage water for the presence of MPs, collected in different drinking water treatment plants (DWTP, n = 9) and water taps (TW, n = 9) in the geographic region of Flanders (Belgium). We report measured microplastic concentrations, size distributions, and polymer types using μFTIR spectroscopy in the range of 25–1000 μm. The MPs’ abundances in the DWTP and TW samples were on average 0.02 ± 0.03 MPs L− 1 and 0.01 ± 0.02 MPs L− 1, respectively. We did not find significant differences comparing the obtained MP concentrations according to the origin of the water. Polypropylene (PP) and polyethylene terephthalate (PET) were the most common polymer types detected in the samples. Next, based on several theoretical assumptions, we extrapolated the measured MP concentrations in our samples to cover the full theoretical MP size range (1–5000 μm) to obtain estimates of the actual MP contamination levels. The rescaled particle concentrations (1 μm – 5000 mm) were on average 5.59 MPs L− 1 and 3.76 MPs L− 1 for the DWTP and TW samples, respectively. Based on a standard consumption of two liters of drinking water per day in combination with the measured concentration in this study, Flemish people consume 0.02 MPs per capita per day via drinking water. These findings contribute in our understanding of the microplastic pollution of drinking water, which is of concern due to the potential uptake of MPs in the human body.