Water pollution worldwide has already endangered health and environment. At places of rapid population growth and urbanization, traditional technologies for wastewater treatment and polluted water reclamation are approaching their limits. Nanomaterials of small particle sizes, huge specific surface areas and abundant reactive sites are ideal for adsorbing pollutants, but semiconducting nanoparticles that can harness sunlight to catalyze advanced oxidation processes are especially effective for eliminating refractory water contaminants. This paper reviews the guiding principles of nanomaterial adsorption and photocatalysis for advanced water treatment, and calls attention to low-cost, high-performance nanomaterials that are well positioned for large-scale water treatment. Black titania (BT) capable of full-spectrum solar photon absorption and three-dimensional graphene (3DG) with an unparalleled combination of electrical conductivity, mechanical strength/flexibility and surface activity and functionality are especially promising. Hybrids of BT and 3DG have been successfully field-tested for large-area remediation of contaminated water in its natural setting, and the lessons learned will lead to further advances in this technology, including ones that integrate wastewater treatment with energy conversion and storage. (C) 2019 Elsevier Ltd. All rights reserved.