Commentary on the article “Overestimation of water pressure by traditional water footprint: Method revision and application” by Liu et al. (DOI 10.1016/j.ecolind.2024.112225)

The recently published article "Overestimation of water pressure by traditional water footprint: Method revision and application" (Liu et al., 2024) contains a number of ambiguities and imprecisions, which could be described as errors in the use of the water footprint (WF) methodology, and thus, the presented results are not correct, respectively do not capture human appropriation of water resource use as explained and justified by the concept developers.At the same time, the article introduces the concept of the so-called blue-grey water footprint.In this contribution, first, the ambiguities in the published article, which probably stem from a misinterpretation of the WF concept, are critically discussed.Then, the "blue-grey water footprint" introduced is reviewed and further discussed, especially regarding its inconsistency with the principles of the WF concept introduced in the Water Footprint Assessment Manual by Hoekstra et al. (2011).This commentary focuses on the major flaws and discusses the most relevant shortcomings of this article.