Ground‐water quality monitoring network design is defined as the selection of sampling sites and (temporal) sampling frequency to determine physical, chemical, and biological properties of ground water. The main approaches to ground‐water quality monitoring network design were identified as hydrogeologic and statistical. The various methods for network design available in the hydrologic literature have been evaluated by considering the spatial scale of the monitoring program, the objective of sampling, data requirements, temporal effects, and range of applicability. Considerable advance has been made over the last two decades that now permit the application of methodical and testable approaches to ground‐water quality monitoring network design, although they mostly serve for preliminary analysis and design. The opinion of the Task Committee on Ground‐Water Quality Monitoring Network Design is that as there continues to be advances in hydrogeochemistry, ground‐water hydrology, and risk and geostatistical a...