A flexible framework for assessing the sustainability of alternative water supply options

Increased water scarcity is driving water utilities to consider alternative water supply options (WSOs). Identifying the most sustainable WSOs that meet environmental, economic, and social objectives is challenging due to the overwhelming number of both assessment criteria and treatment configurations, including a growing number of potable reuse options. Conventional approaches using process-based life cycle assessments are data-intensive and site-specific, and therefore not suitable for the early stages of assessing WSOs. To address this gap, we have combined hybrid multi-regional input-output-based life cycle assessment (MRIO-LCA), social impact analysis, and multi-criteria decision analysis (MCDA) to develop a novel, flexible framework with unit process level resolution for the comprehensive evaluation of WSOs. Here we describe the formulation of the framework along with an application to two US utilities considering alternative WSOs. In both cases, given sufficient levels of community acceptance and optimum system design, the results favoured potable reuse WSOs due to their climatic resilience, cost effectiveness and lower environmental impacts (compared to other non-conventional options such as desalination). The generalised and globally applicable framework developed for this study can be used to assess sustainability trade-offs between diverse WSO configurations, providing valuable insights for decision-making processes at the early planning stage, as a complement to existing urban water supply scenario and optimisation models.