Characterizing prevailing precipitation regimes from a comprehensive database of 11 observational data sets, this chapter first analyzes the fidelity of 36 state-of-the-art global climate model experiments from the Coupled Model Intercomparison Project Phase 5, and then presents changes in the surface water budgets from moderate-to-high fidelity experiments under the Representative Concentration Pathway (RCP) 4.5 for the 21st century. Results suggest that the water balance is not closed for 13 experiments, while one-fourth of the analyzed experiments do not see the monsoonal precipitation regime at its extreme margins over the Indus Basin. Nevertheless, 14 moderate-to-high fidelity experiments agree on a decreasing water budget for the westerly precipitation regime, which dominates during spring, and over the Upper Indus Basin. In contrast, a moderate agreement suggests a consistent increase in the water budget during the monsoonal precipitation regime over an extended area. Overall, the water budget changes are small, suggesting a drier Upper Indus Basin but a wetter Lower Indus Basin in the future.