Knowledge of the transport processes of bulk fertilizers and other solutes in soils and porous media is vital to understanding the environmental and economic impacts of many agricultural and waste disposal practices. Previous experimental research shows that significant water movement can occur towards regions of high salt concentrations in unsaturated porous media. It is hypothesized that in unsaturated media, large gradients in aqueous osmotic potentials cause significant water‐vapor fluxes towards regions of high solute concentrations. A physically based model to describe this process is developed by combining existing theories of liquid‐water and water‐vapor transport with aqueous electrolyte theory. A simplified solution, demonstrating these water‐vapor transport processes, is compared with experimental results from discontinuous soil column experiments previously published by Wheeting (1925) The results confirm that large osmotic potentials created in the presence of high solute concentrations in unsaturated porous media, can account for the quantities of water vapor movement observed. This redistribution of pure water vapor complicates modeling of ion diffusion in these systems and is an important process to include in solute transport models when high solute concentrations exist in unsaturated soils.