Operationalisation and application of water supply mix (WSmix) at worldwide scale: how does WSmix influence the environmental profile of water supply for different users?

Purpose A worldwide-regionalized water supply mix (WSmix) has been developed for use in life cycle assessment (LCA) studies. The WSmix is the combination of water sources and water technologies to meet a water user need at a specific time (season, month) and location. A global database has been computed to collect information on water sources and users at country and river basin scales. However, its application to LCA case studies at different locations and for different users has not yet been fully tested and analysed. The aim of this study is to operationalise WSmix for application in LCA and to test the added value and usability of WSmix by applying it worldwide to two different systems, a service and a global product, considering different climatic and socio-economic conditions. Methods The WSmix is applied to two main water users, the results are analysed, and the variability of the WSmix for 91 countries with different socio-economic conditions is discussed. Some examples of the variability of the water sources mix (WOmix) and the temporal variation at river basin scale are presented. Results and discussion The results show that the WSmix has a great influence on the environmental profile of water supply for different users considering different climatic and socio-economic conditions. Moreover, the interdependence between water and energy (i.e. water-energy nexus) is clearly established, which reinforces the importance to link a regionalized WSmix with national/regionalized electricity mix. Conclusions In conclusion, the WSmix has been operationalised and applied in LCI databases. Its added value and usability has been demonstrated by applying it at a worldwide scale for two different users. Methodological developments are still required to increase its spatiotemporal resolution, and LCIA methods need to be improved to better consider its different components (including water sources).