The influence of biofouling on zooplankton ingestion rates of plastics in freshwater environments has received limited attention. We investigated how biofouling of microplastics in wastewater effluent and in fresh surface water influences Daphnia magna's microplastic consumption. The differences in ingestion of the biofouled as compared with the virgin microplastics were higher for the surface water by a factor of seven compared with a factor of two for the effluent. The intake of biofouled microplastics by D. magna was higher compared with virgin plastics, but the reason for this preference should be further investigated. Environ Toxicol Chem 2022;00:1–6. © 2022 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.