Water sustainability is central to modern political and academic debates. Despite increasing efforts to promote regional and global integrated water management, climate change, population, and economic growth, and increasing consumption of water-intensive goods project higher water deficiency. Robust economic analyses rely on information about water supply and consumption across different production sectors, type of procurement source (public or private water supply), and water prices. Nevertheless, developing current and future economic water assessments and indicators is impeded by the absence of data. Despite the lack of official national statistics on water withdrawal and consumption, a small number of international and global databases have been constructed and attempt to combine available national water information into databases. Water databases do not commonly define and/or distinguish terms such as water use, water consumption, water supply, or water abstraction, and the associated aspects of water scarcity and sustainability. They comprise variable data quality, provided by numerous sources, and estimated values. This paper evaluates the current state of knowledge of national statistics, international and global water databases. We describe the data collection methods, identify basic concepts and definitions of water terms, followed by the criteria of consistent water databases. We inform about data availability across regions, and present the data content and definitions of national, international, and global water databases. The results show inconsistencies of data content and definitions, suggesting no evidence of data harmonization among databases. Therefore, our study cautions researchers to be careful when manipulating and comparing the available water data, especially when deriving policy recommendations or economic conclusions. In the long run, the headway of water research and political assessments depend on political enforcements to refine the meaningfulness of water data and support water collection, reporting, and monitoring. Alternatively, in the short- and medium-run, water data challenges can be addressed by joint research efforts for water data harmonization.