This research paper focuses on water demand projections (WDPs) which are widely used for future water resource planning. It argues that accurate WDPs can reduce waste or scarcity associated with overdevelopment or underdevelopment, respectively, of water resources. The paper examines how closely such past projected withdrawals match current water withdrawals to identify lessons that can be learned and strengthen future studies on WDPs. Six WDPs conducted before 1990 and seven conducted after 1990 are analyzed in detail. The review shows that the pre-1990 WDPs, which considered population as the main driver of change, overpredicted current water use by 20 to 130%. Unrealistic assumptions on the norms of water use in different sectors were the main reasons for large discrepancies. The post-1990 WDPs had sophisticated modeling frameworks. They integrated many exogenous and endogenous drivers of food and water supply and demand, with refined estimation procedures for domestic and industrial sectors.