Environmental, economic, and social sustainability of urban water systems: a critical review using a life-cycle-based approach

The increasing number of studies covering different life cycle sustainability assessment (LCSA) tools and urban water systems (UWSs) emphasize the need to synthesize current research. While LCSA studies focus on an integrated approach considering the life cycle assessment (LCA), Life Cycle Costing (LCC), and social life cycle assessment (S-LCA) methodologies, these tools are typically applied separately, disregarding the trade-offs amongst economic, social, and environmental impacts. In this context, this review aims to critically analyze the literature on LCSA tools to enhance the integrated application in the future. Furthermore, we aim to identify technological trends, current challenges, and future research directions to improve sustainability. The ProKnow-C methodology was applied using a combination of four keyword sets and three databases. We selected 72 relevant papers that were analyzed in detail. Results demonstrate that authors apply different boundaries when using different LCSA tools, and lack of data was also a common issue. Furthermore, papers lack system description in the scope definition, leading to a biased interpretation of results. Another important issue was the functional unit selection, which did not represent the complexity of UWSs, lacking important details such as water loss, water quality, and population served. Water treatment is the most researched process in UWSs, and stormwater systems (collection or treatment) are rarely included, representing only 25% of the analyzed literature. In conclusion, the application of LCSA tools faces fundamental challenges, such as data quality and availability. Concerning the engineering improvements, future works should use LCSA data to support design and technology development, also focusing on human behaviour and frugal technology alternatives. Finally, new paradigms need to be developed and applied to enhance sustainability and integrate UWS.