The object of this study was to produce a single, robust groundwater dataset for South Australia that could be combined with other datasets sourced from elsewhere across Australia. Utilising historical data qualified by minimal metadata is not ideal for geochemical accuracy. However, given the number of samples (~32,000) and their potential utility, it is advantageous to extract useful data from these samples. The South Australian groundwater data was therefore subject to a thorough quality assurance / quality control (QA/QC) assessment. Data that did not pass the assessment was rejected. Though it cannot be assured that all erroneous data had been removed (with particular concern for individual trace metals with concentrations variously expressed in mg/L or g/L), these instances have been minimised, and the data in consequence appear coherent. By combining them into one file having values with consistent detection limits, and by correcting some of the older data for the effects of past analytical method differences when compared to the derivation of recent data, all of the data should now have been rendered readily usable and “seamlessly” comparable. The South Australian groundwater hydrogeochemical data is now being combined with other datasets by CSIRO, in order to map the groundwater chemistry of major geological regions within Australia. Deriving relatively simple parameters showing a spatial variation, such as ion ratios and ion excesses, as well as mineral saturation indices, gives useful input into geological, geochemical and geomorphological mapping.