Many years’ extraction of groundwater in the context of established usable groundwater reserves.
Jan Macuda, Ewa Styrkowiec
Vol. 34, no. 2 (2017), pp. 419-426, 
The operation of water supply networks basically relies on the ability of supply water, which in the case of groundwater intakes, is defined by usable reserves offered by the wells involved. Their establishing is the last stage of an investment, i.e. building of groundwater intakes, and their value determines the type of infrastructure and technological hardware in the wells. Owing to the fact that the usable groundwater reserves are conditioned by a number of factors (economic, technological, environmental) their correct determining depends on the correct definition of the number and quality of measurements and hydrogeological observations. In practice, these measurements tend to be shortened to minimum (test pumping) or discarded (diagnostics of well construction) for financial reasons. As a result the user obtains either over- or underestimated information about the intake parameters. Exploitation of a well with overestimated capacity brings about serious technological and economic consequences, starting from the lowered productivity (drop of water table, lower yield), change of chemical composition of water, sanding up of the well as well as well failures and damage. The use of a well with underrated output does not shorten the life of the well, though is disadvantageous for the economic reasons. The productivity of wells can be verified after a few years of controlled extraction, on the basis of which the cost of water extraction, stability of chemical composition or impact on other intakes in given work conditions. Accordingly, this is a basis for updating usable groundwater reserves of the wells. Moreover, after many years of observation of groundwater intakes, one can formulate recommendations warrantying long life of wells, rational management of pump aggregates and well renovation plans.