Assessing the environmental impact of freshwater use in LCA: established practices and current methods

Abstract

Freshwater, an essential resource for survival, is becoming scarce because of overuse. A reliable and precise assessment approach is necessary to establish a sustainable water system for use in proper decision-making. This paper explores the range of approaches and methods developed over time to evaluate water consumption, considering factors related to scarcity, quality, and volume. These methods are primarily based on volumetric footprint, impact-oriented assessment, or a combination of both. The water footprinting standard defines water footprint as impact-oriented, where volumetric approach serves as an inventory in life cycle assessment (LCA), which is a widely used tool for evaluating the environmental impact of a product or a system throughout its lifetime. The work provides a thorough overview of more than forty different approaches, tools, databases, and water indices related to water use, water footprint and its environmental impact using life cycle assessment tool and compiled from more than sixty reviewed articles. Many approaches focus on availability and shortage while water quality is generally considered separately, with LCA employing specific indicators. To calculate the impact of scarce freshwater supply on the environment, methodologies are being developed to create a connection between water availability, use and impacts. This is accomplished by employing various characterization models that use environmental mechanisms to convert volumetric input flows into impacts. Some models use cause-and-effect chain relationships to evaluate the effects of water scarcity on ecosystems, human health, and natural resources. Water indices, usually focusing on scarcity or quantity, are used as characterization factors in some models. The paper also presents the most recent approaches to water use assessment that emerged from a consensus between the LCA and water scientific groups. Despite substantial progress, challenges are still present within the sector. Continuous improvement is essential for improving current methods. Enhancing environmental mechanisms, measuring uncertainty, resolving temporal and spatial disparities, undertaking regional evaluations, and improving primary or local data are some of the challenges. This study directs future research toward more efficient and comprehensive water use impact assessment techniques by outlining important areas for improvement.