Septic systems are considered to be one of the most extensive contributors to groundwater contamination in North America. With approximately 30% of the population in North America utilizing septic systems, there exists a need to understand how various characteristics influence contaminant transport. The objective of this study was to use an available computer model, FEMWATER, to simulate an already existing absorption bed. The model was used to examine how the biomat, contaminant characteristics, and absorption bed characteristics affect contaminant transport. The results from this research showed that the dispersivity is the most important characteristic in determining contaminant transport followed by adsorption, decay, and groundwater velocities. It is recommended that the OBC guidelines be amended to incorporate the direction of groundwater flow and that drinking water wells should be located upstream or laterally 30 m from the absorption bed.