• A field-scale problem of pumping energy consumption minimization was solved. • Coupling of a groundwater flow model with an optimization algorithm was performed. • The optimization algorithm is based on an analytical solution. • The optimal pumping strategy under various problem setups was examined. • The importance of including friction losses in such problems was highlighted. Global population growth and rapid economic development, along with modern goals for creating sustainable communities, render it necessary to focus on fundamental, finite resources such as water and energy. The interdependencies between water and energy are well known, while recently the interest of the scientific and policy communities on their dependency relationship has grown noticeably. On the one hand, water is used throughout the energy industry, while, on the other hand, the water system needs energy for collecting, pumping, supplying and treating water. Considering the latter case, great importance should be given when specifically referring to groundwater resources for the abstraction of which a large amount of energy is generally required. Therefore, minimizing the energy consumed for pumping groundwater is extremely important, and, for this reason, a large number of studies have been conducted in order to address this certain issue. However, most of the studies dealing with pumping cost minimization problems ignore the effect of friction losses on the total energy consumed for pumping and transporting groundwater. Under this perspective, the present paper attempts to highlight the importance of including friction losses in such type of problems by combining a simulation model and an optimization algorithm. Through the formulation of different setups of the same problem, that is the energy cost minimization for pumping groundwater from a system of wells and transporting it through transmission lines, it was found that only when including friction losses in the optimization problem, all managed wells are being used for pumping water, thus resulting in more reasonable and workable solutions.