The aim of the study is to demonstrate the impact of human activity on the process of alteration of natural hydrological conditions in subsurface stratified geologic formations. The Pleistocene and Upper Pannonian layers of the Great Hungarian Plain are reservoirs of huge amount of fresh water. In Hungary 80 per cent of water wells are drilled on Pleistocene aquifers. In the first half of the last century most of the wells were effluent ones in the Great Hungarian Plain. The extended abstraction of large quantity of water in the second half of the century resulted in remarkable sinking of potentiometric surface (hydraulic head) of water in aquifers and issued in drawdown of regional scale. The pattern in Fig. 1 shows a distinct change of radiocarbon age near the Debrecen waterworks I. and II. resulting in leakage from superjacent layers containing younger water. The effects of human activity are studied in a vertical section of 100 km length in North-Eastern Hungary (Fig. 2). Changes of total heads of aquifers along the line are reported in Table 2. The time-dependent changing of depression curves of great extension is shown in an additional section (Fig. 3). Since the years of 1990th the water extraction has been decreased in Hungary by 40-45 per cent. Thereupon the hydraulic heads began to rise in the vicinity of water works, but in larger distances (8-10 km) the heads were kept on sinking. This phenomenon is a clear manifestation of hydraulic continuity of large stratified sediment basins.