Groundwater quality aspects are among the most significant indicators as for the groundwater usage categorization for domestic and especially agricultural activities, water mixture from different quality regions in the same aquifer of among different aquifers, and recharge calculations. Major cation and anion compositions and their chemical balance are explained such that in practice within a certain error limits the groundwater quality aspects can be acceptable for further assessments. Different classical and innovative graphical representations of chemical composition ions are presented with emphasis on the groundwater quality classification. Some drawbacks in the classical approaches are explained and better alternatives are suggested such as the ion-concentration-frequency and multirectangular diagrams. Groundwater recharge calculations based on the chlorine mass-balance approach is updated with uncertainty ingredients that takes into consideration not only the arithmetic average but also the standard deviation of the measurements. Groundwater rise problems and related quality variations are explained. Two new concepts are introduced for groundwater quality variation inspections, which provide ways of collective quality measurement from a set of sites both temporally and collectively. These are individual and successive standard ion indicator methods. As for the water quality index similarity models and quality association matrices are presented with applications. Throughout the text a set of convenient practical and numerical hydrochemistry examples and problems are presented with associative solutions.