The role of food categories in shaping socioeconomic impacts on the water footprint of household food waste

Household food waste poses a serious threat to planetary boundaries, particularly regarding water use, since it translates directly into unnecessary consumption of virtual water, contributing to freshwater depletion and threatening water security in water-scarce regions. This study examines how household socioeconomic factors differentially drive the water footprint embedded in food wasted, and how these impacts vary across food categories. To do so, we combine detailed data on food waste quantities of representative Spanish households for the period 2018–2022 with data on unitary water footprint of consumption, in order to calculate the volume of virtual water embedded in food discarded by households. We then employ a pooled regression approach to estimate the socioeconomic characteristics influencing it, analysing differences across food categories and testing how the impact of household characteristics varies by categories. Our results reveal that higher socioeconomic status and larger households significantly increase the water footprint of food waste, while the age of the main shopper and the presence of children are associated with a reduction. Moreover, our findings show that the water footprint of vegetables and other foods categories is more sensitive to socioeconomic status, while the water footprint of meat and dairy categories shows a stronger effect driven by age and household size. These insights offer policymakers valuable guidance for the design of tailored policies for specific groups to reduce the water usage, focusing not only on those products with a higher waste level, but also with a higher water footprint.