Water composition is defined by measuring the amounts of its various constituents; these are often expressed as milligrams of substance per litre of water (mg/L). Sampling methods vary according to the types of analysis. Dataset point: The dataset represents a general description of the sample, including name, ID, type of analysis and lab. It includes numbers describing the results of the analysis and physical properties of groundwater. Time series: The dataset represents a general description of the sample, including name, ID, type of analysis and lab. It includes series of numbers describing the results of the analysis and physical properties of groundwater with associated date. Dynamic values over time at the same sites provides temporal variation data of groundwater composition.