Improperly assuming the aquifer ends at the bottom of wells can lead to wrong estimates of how easily water flows through the ground. By using incorrect thickness values, estimates of hydraulic conductivity can be too high. This can cause mistakes in predicting how fast contaminants spread in groundwater, how much water is available, and where water can be captured. The error in conductivity estimates is linked to the error in assumed thickness and the ratio of vertical to horizontal conductivity.