The purpose of this study is to improve the understanding of confinement conditions and land use on the the variability of water quality (nitrate, VOCs and pesticides) within parts of the Upper Floridan aquifer under different confinement conditions. All water-quality data used for this study were collected and compiled as part of the USGS NAWQA program from 1998 to 2005. Results for water samples from 148 domestic wells in the Upper Floridan aquifer were compared based on unconfined, semiconfined and confined areas and by agricultural, urban, and undeveloped land uses.