A water influx model is developed which incorporates two principal mechanisms: unsteady-state radial permeation and spalling-enhanced drying of the overlying coal and overburden. These mechanisms are coupled via a cavity growth model. The model predictions follow the general trends for the daily average water influx for the Hanna II Phases II and III, and Hoe Creek II DCG field tests error of 13.1 percent. The model indicates that the water influx per unit mass of coal consumed increases as the seam thickness decreases pr as the reverse combustion link is completed progressively higher in the seam. A DCG operating strategy is suggested whereby the water influx per unit mass of coal consumed can be maintained nearly constant.