This International Standard describes the factors to be considered and the measurements to be made when designing and performing a pumping test, in addition to a set of guidelines for field practice to take account of the diversity of objectives, aquifers, groundwater conditions, available technology and legal contexts. The standard specifies the fundamental components required of any pumping test. It also indicates how they may be varied to take account of particular local conditions. It deals with the usual types of pumping test carried out for water-supply purposes, in which water is abstracted from the entire screened, perforated or unlined interval(s) of a well. Interpretation of the data collected during a pumping test is referred to in this International Standard only in a general way. For full details of the analysis and interpretation of test data, reference should be made to specialized texts. Examples of such texts are included in a selected bibliography.