Aquifers of the Roswell groundwater basin are unconfined and confined types in Permian San Andres Formation and Artesia Group carbonates and evaporites, and the shallow unconfined Quaternary sedimentary and alluvial aquifer. The carbonate-evaporite aquifers were developed from solution by meteoric water, groundwater, the Pecos River, and its tributaries. The structural geology of the region includes Cenozoic folding and wrench faulting. Regional dextral strike-slip faults, <30 Ma to as young as 0.5 Ma, dominate the hydrogeologic framework of the groundwater basin. The faults created major lithologic and structural boundaries for the groundwater systems developed between them. The Roswell groundwater "basin" is actually a series of en echelon structural blocks with aquifers developed in erosion-beveled, fault-displaced Permian carbonates and evaporites partly covered by Quaternary sedimentary rocks and alluvium. The confined portions of the carbonate aquifers are in the San Andres Formation, the Artesia Group, or a solutional-karstic melange of the two. The Permian aquifers developed within each structural block exhibit different hydrochemical and hydrologic properties. The rock groups produce distinctive bulk element water chemistry signatures which are readily visible on ternary plots, Piper diagrams, and Fingerprint diagrams. San Andres Formation waters have high HCO₃⁻, intermediate SO₄²⁻ , and low Cl⁻ that demonstrate a preponderance of carbonates with some evaporites. Waters hosted by the Artesia Group are characterized by low HCO₃⁻, high SO₄²⁻ , and high Cl⁻that reflect evaporites with some carbonates. Quaternary alluvial aquifer waters show low Ca²⁺, low HCO₃⁻, with moderately high SO₄²⁻- and Cl⁻. Normative mineral reconstructions identify the lithologic combinations through which the waters flowed to acquire their present chemical characteristics. Plotted as charts the normative mineral reconstructions can be correlated as are electric well logs. Mineral stability diagrams support exchange by sodium liberation and calcium replacement in Na-smectite marine clays for altering the Ca⁺ - Na⁴ groundwater chemistry. Hydrochemical plots provide a robust means of identifying aquifer sources of groundwater and delineating their structural and stratigraphic boundaries. The work should be expanded to include more water analyses from each group, and as a means to identify unknows, such as the sources of water to the Pecos River.