Trends in global greywater reuse: a bibliometric analysis

The increase in water demand in recent years led to the expansion of research and public policies on the reuse of water, especially greywater (GW). Given the diversity of research in the area, this paper proposes an analysis of the evolution of the area through an objectivity metric. Metadata of 1,524 publications indexed in the Scopus database between 1974 and 2021 were analyzed using the VOSviewer tool, and showed exponential growth in publications from 2013. Six different spelling variations were found for GW in the database. Despite the highly geographical scattering of academic production, developed countries, who began researching greywater earlier, had more connections and published more papers; except for Israel, which had the highest average of citations per article. While developed countries lead the research area, developing countries are emerging in GW reuse research. These aspects reveal both the dispersion of the research structure development and a trend of intellectual production in GW from developed to developing countries. Also, we noted that countries suffering from water scarcity stood out with the highest activity in paper publishing. Thus, we expect that future research on GW reuse will take place in developing countries that face water scarcity.