Nano-enabled consumer products are a likely source of nanoparticles in the environment and a number of studies have shown the release of nanoparticles from commercial products. Predicted environmental concentrations have been calculated but there is a need for real measurement data to validate these calculations. However, the detection of engineered nanoparticles in environmental matrices is challenging because of the low predicted environmental concentrations which may be in the ng/L range. In this study nanosized Ag, CeO2 and TiO2 have been measured in multiple surface water samples collected along the rivers Meuse and IJssel in the Netherlands using single-particle ICP-MS as measurement technique. Validation of the analytical method showed its capability to quantitatively determine nanoparticles at low concentrations. Concentration mass detection limits for Ag, CeO2 and TiO2 were 0.1 ng/L, 0.05 ng/L and 10 ng/L respectively. Size detection limits for Ag, CeO2 and TiO2 were 14, 10 and 100 nm. The results of the study confirm the presence of nano-sized Ag and CeO2 particles and micro-sized TiO2 particles in these surface waters. n-Ag was present in all samples in concentrations ranging from 0.3 to 2.5 ng/L with an average concentration of 0.8 ng/L and an average particle size of 15 nm. n-CeO2 was found in all samples with concentrations ranging from 0.4 to 5.2 ng/L with an average concentration of 2.7 ng/L and an average particle size of 19 nm. Finally, μ-TiO2 was found in all samples with a concentration ranging from 0.2 to 8.1 μg/L with an average concentration of 3.1 μg/L and an average particle size of 300 nm. The particle sizes that were found are comparable with the particle sizes that are used in nanomaterial applications and consumer products. The nanoparticle concentrations confirm the predicted environmental concentrations values in water for all three nanoparticles.