Life cycle assessment (LCA) of urban water infrastructure: emerging approaches to balance objectives and inform comprehensive decision-making

Life cycle assessment (LCA) has been widely used to quantify environmental impacts associated with urban water infrastructure, including wastewater, drinking water, stormwater, and integrated urban water systems. While LCA is applicable for the estimation of global environmental impacts, decision-makers must balance these impacts with local, often regulated, environmental and public health objectives. To characterize the state of the art for the use of LCA for urban water infrastructure, a thorough literature review was conducted of papers that applied LCA to wastewater (173 papers), drinking water (44 papers), stormwater (17 papers), and integrated urban water (22 papers) systems. Analyses revealed current preferences for functional unit basis (e.g., volume for wastewater), system boundaries (e.g., focus on operation), and impact assessment methodology (CML, ReCiPe, and Eco-Indicator). Based on these findings, LCA methodological recommendations for urban water infrastructure are made, and emerging opportunities to balance objectives and inform comprehensive decision-making are discussed. Critical opportunities include the integration of spatial considerations (e.g., spatialized characterization factors), water quantity (e.g., water quantity indicators), public health (e.g., integration with risk assessment), economic and social assessments (e.g., life cycle costing and social LCA), along with prioritization of continuous stakeholder engagement. Finally, research and development needs specific to the use of LCA for urban water infrastructure (e.g., development of new indicators coupled with case studies) are prioritized.