The most severe outlooks identified by the study are concentrated in sub-Saharan Africa and the Middle East. These regions already face limited access to clean water in many areas and are projected to experience substantial population growth. Under the researchers’ modeled scenarios, demand for domestic water in these regions could increase by as much as 1,225 percent. When the additional effects of declining water quality are included, the study estimates that the effective water shortage could rise to nearly 2,000 percent. These figures represent projected changes relative to the study’s baseline conditions, rather than a literal loss of 2,000 percent of today’s water supply, but they illustrate how quickly demand and quality pressures can amplify one another.

link to open access paper https://www.nature.com/articles/s41545-026-00608-0

a Total water gap (i.e., sum of all sectoral water gaps), where pie chart indicates percentage of inhabited areas affected by a specific driver; b per sector (i.e., domestic, irrigation, livestock, manufacturing, and thermoelectric). Quantity driven indicates insufficient water availability to meet sectoral water quantity demands (no water quality constraints), quality driven indicates exceedance of water quality thresholds for sectoral use (sufficient water availability), and their combined effect indicates that both water quantity and quality issues drive the water gap. Data employed correspond to the ensemble mean of the simulations performed using bias-corrected output of five GCMs for the global change scenario SSP3-RCP7.0. Displayed drivers are the most recurrent annual water gap driver over the period 2081–2100 over each grid-cell.