The HYDRUS computer software packages simulate the one-, two- or three- dimensional movement of water, heat and multiple solutes in variably saturated media. The program numerically solves the Richards' equation for saturated-unsaturated water flow and Fickian-based advection dispersion equations for heat and solute transport. The Flow equation incorporates a sink term to account for water uptake by plant roots. The Heat transport equation considers conduction as well as convection with flowing water. The Solute transport equations consider advective-dispersive transport in the liquid phase and diffusion in the gaseous phase. Hydrus numerically solves problems such as root water and solute uptake, infiltration from ponding, rainfall and irrigation, irrigation scheduling, bacteria, pesticide transport in soils and more.