The properties and fate of nanomaterials in water affects their potential environmental impacts and risk for human exposure. In this study, the physicochemical characteristics of six commercial metal oxide nanoparticles, a lab-synthesized hematite nanoparticle and a water-soluble CdTe quantum dots (QDs), their removal from water by conventional drinking water treatment processes and their toxicity on cells were examined. These nanomaterials exhibited different stability in water and conventional water treatment could not remove them completely. Toxicity studies showed that TiO2 nanomaterials could flatten down the microvilli of cells, decrease Trans-epithelial Electrical Resistance (TEER) and pass through the epithelial cells. These results imply that nanomaterials in drinking water may pose a potential exposure risk for human.