Inadequate sampling of the water and their transport to the laboratory is sometimes the cause of erroneous results, regardless of the high class equipment used for the laboratory tests. Field studies are the basis of each sampling aimed to characterize of the groundwater chemistry. Such measurements are often mistaken, what hinders interpretation of the results. The purpose of this article is to demonstrate the correct way to perform basic field research (associated with the collection of a representative sample of groundwater and its preliminary tests) and suggestions how to avoid common errors. In the article it has been analyzed: how to collect of the samples, measurements of the quickly changing parameters, researches which are necessary for conducted in the field and researches feasible to performed in the laboratory.