Categorizing water for LCA inventory

Purpose As impact assessment methods for water use in LCA evolve, so must inventory methods. Water categories that consider water quality must be defined within life cycle inventory. The method presented here aims to establish water categories by source, quality parameter and user. Materials and methods Water users were first identified based on their water quality requirements. A list of parameters was then defined, and thresholds for these parameters were determined for each user. The thresholds were based on international standards, country regulations, recommendations and industry standards. Three different water sources were selected: surface water (including seawater), groundwater and rainwater. Based on the quality and water sources, categories were created by grouping user requirements according to the level of microbial or toxic contamination that the user can tolerate (high, medium or low). Results and discussion Seventeen water categories were created: eight for surface water, eight for groundwater and one for rainwater. Each category was defined according to 136 quality parameters (11 conventional parameters, 38 specific inorganic contaminants and 87 specific organic contaminants) and the users for which it can be of use. Conclusions A set of elementary flows is proposed in order to support a water inventory method oriented towards functionality. This can be used to assess potential water use impacts caused by a loss of functionality for human users.