The perspective of future sustainable urban environments focuses on buildings that not only achieve energy efficiency but also actively contribute to sustainable water use. This chapter addresses the pressing challenges of urban water systems amid increasing water scarcity, exploring how innovative passive solutions like fog harvesting can complement traditional water sources and improve the energy efficiency of buildings. It examines the operational mechanisms of fog harvesting, the required atmospheric conditions, and its application in both urban and rural contexts. Case studies and water collection data are analyzed to showcase its potential. Particular attention is given to integrating fog harvesting into building envelopes, such as double-skin facades, which can collect water while reducing energy consumption in buildings through shading. Lastly, the chapter discusses the limitations of fog harvesting technology, its impact on urban water consumption, and its potential role in shaping a sustainable built environment.