Three important considerations in designing a groundwater data collection program are (1) a clear understanding of the activities needed to solve a general groundwater management problem, (2) an explicit classification scheme for the physical and water quality models of a groundwater system, and (3) an understanding of the concept of accuracy and its use in the design of a program. The first consideration is important for the formulation of a well‐stated groundwater problem. The second consideration is important for the communication between resource managers and hydrogeologists. The third consideration is important for the estimation of the effort to be expended in a collection program. A classification scheme for the physical and water quality models of a groundwater system is proposed. The scheme is based on three types of physical models: (1) aquifer, (2) water budget, and (3) hydrodynamic; on three types of water quality models: (1) energy and chemical mass characteristics, (2) energy and chemical mass balance, and (3) energy and chemical mass transport; and on three types of model representations applicable to each physical and water quality model: (1) descriptive, (2) empirical, and (3) mathematical.