Increased awareness regarding water pollution and resources conservation due to water scarcity and climate change, combined with intensive urbanization and agricultural production, have raised the need for removal of contaminants of emerging concern (CEC) from treated effluents. CEC include, among others, pharmaceuticals, cleaning and sanitation products, endocrine disrupting compounds, suspected carcinogens, and nanomaterials at trace concentration. Added to this are antibiotic‐resistant bacteria (ARB) and antibiotic‐resistant genes (ARG). Conventional wastewater treatment removes bulk organic contaminants leaving CEC in the effluents. This article discusses the incorporation of advanced treatments such as oxidation processes, adsorption, and tight membrane separation, i.e. reverse osmosis (RO), aimed at removing CEC from effluents. Owing to its generic capability to remove dissolved organic and inorganic contaminants at once, RO appears as the core technology for effluents purification. Besides improvements of existing municipal effluents, changes in conception, management and planning of the urban water systems, e.g. reduction at source and decentralization approaches, are required. Removal of dissolved organic pollutants and mineral contaminants at trace levels cannot be done without consuming energy. The water–energy nexus and related life cycle analyses need to be rethought in terms of environmental and health risks and deterioration of water resources and soils.