This hydrogeochemical atlas for South Australia builds on the accompanying notes to the revised hydrogeochemical data from the SA_Geodata groundwater dataset. The dataset is available online (Gray and Bardwell, 2016a; http://doi.org/10.4225/08/5756B3BF09204) and is part of the ‘Continental Scale Hydrogeochemistry’ initiative. The atlas aims to examine regional trends in groundwater chemistry, determine links to underlying lithology and aquifer sources and, if possible, present new areas of interest for mineral exploration. One of the major issues when combining multiple datasets of geochemical sampling results in order to create seamless regional data mapping is that different datasets were collected at different times, analysed through different instruments, and, in the case of some of the older data, these may have been collected using different analysis methods. All datasets included in this atlas have been put through extensive quality assessment/quality control checking. A number of different hydrogeochemical data parameters can be used to help indicate the composition of buried rock types, even when there is deep weathering or transported cover. Higher dissolved concentrations of elements can indicate mafic (Cr, V) or granitic (U, F) rocks, while ratios between elements (e.g. K excess relative to Rb) can differentiate between granitic and sedimentary terrains. These determinations are improved by considerations of multi-element indices and mineral saturation indices. For example, spatially the carnotite saturation index predicts most of the known U prospects. Oxygen and H isotopes highlight groundwater samples that have a composition suggestive of a water source other than meteoric water. This water source has mixed with meteoric water and may be spatially linked to faults, mineralisation or hydrothermal alteration. Individual element values and multi-element associative parameters have been shown to highlight major lithological boundaries as well as major aquifer systems. These aspects provide baselines for conducting environmental and mineral exploration studies on a regional scale. At a smaller scale, some but not all of the major mine camps can be seen in some parameters, depending on the mineralisation style and host rocks, and also the amount of hydrogeochemical data available for each site. Some new areas for potentially finding mineralisation have been identified based on the known mineralisation expressions. These regional data are a starting point, as they demonstrates the value of using hydrogeochemistry for regional lithology mapping, and can aid in the production of geological interpretations under cover. The data are also of value for use in conjunction with smaller scale studies for ore body delineation.