A simple model for temperature within an unconfined semi-infinite aquifer is proposed with groundwater flowing perpendicular to heat flow. Our results show that it is possible to correct the observed geothermal gradient in order to obtain the undisturbed gradient, to identify the portion of the aquifer where the perturbation produced by water motion is unimportant, and to recognize the depth and distance from the recharge zone where water temperature is higher and can be exploited for low enthalpy utilization.