Tethys produces monthly, gridded global water withdrawal data products based on estimates from the Global Change Analysis Model (GCAM), an integrated human–Earth system model (Li et al., 2018). GCAM is often coupled to sectoral models that typically operate at finer scales, and mismatches across time and space can occur. Tethys eliminates such mismatches by using statistical algorithms to downscale global water withdrawal data. Water withdrawals are separated into six common high-volume water-use sectors: irrigation, livestock, domestic, electricity generation, manufacturing, and mining. Downscaling algorithms are parameterized using collected data products and applied to the various sectors. These algorithms downscale the spatial resolution from region/basin scale to grid (0.5 geographic degree) scale and the time resolution from year to month.