The Floridan aquifer system underlies the entire state at varying depths below land surface. However, potable water does not occur everywhere in the Floridan. In these areas, residents obtain water from shallower aquifer systems or through reverseÊosmosis. The Floridan aquifer system is a confined or artesianÊaquifer system. The level to which water will rise in a properly constructed well is called the potentiometric surface. Where the potentiometric surface occurs above the land surface, natural artesian flow of water occurs. The thickness of the freshwater lens in the Floridan varies dramatically from zero to more than 2000 feet. Groundwater levels can be dramatically affected by heavy pumpage of wells. In these areas, the potentiometric surface will show a decline as in Tampa and Pensacola. If the potentiometric surface is drawn down below sea level, salt water may intrude and replace the fresh water.
