At complex sites there may be many potential sources of contaminants within the vadose zone. Screening-level analyses are useful to identify which potential source areas should be the focus of detailed investigation and analysis. A source screening module (SSM) has been developed to support preliminary evaluation of the threat posed by vadose zone waste sites on groundwater quality. This tool implements analytical solutions to simulate contaminant transport through the unsaturated and saturated zones to predict time-varying concentrations at potential groundwater receptors. The SSM integrates several transport processes in a single simulation that is implemented within a user-friendly, Microsoft Excel™ - based interface.