The majority of the freshwater supply in west-central Florida comes from groundwater, most commonly the Floridan aquifer system. The Floridan aquifer system contains the largest aquifers within the state and stretches 100,000 square miles beneath Florida and parts of Alabama, Georgia and South Carolina.
![H20-Zone-Graphics [Water Basics - Floridian Aquifer].png](https://www.swfwmd.state.fl.us/sites/default/files/H20-Zone-Graphics%20%5BWater%20Basics%20-%20Floridian%20Aquifer%5D.png)
The Floridan aquifer system has been divided into the Upper Floridan aquifer and Lower Floridan aquifers. Between the aquifers are confining units made of low permeability rock that water cannot easily flow through. This separates the water in the upper aquifer from water in the lower aquifers. In other words, water becomes trapped in these lower aquifers.
The Upper Floridan aquifer is the primary source of water supply in most of north and central Florida. In the southern portion of the state, the aquifer is deeper and contains brackish, or slightly salty water. The Upper Floridan aquifer is the source of many springs in Florida and is also connected to other surface water bodies.