A pre-Quaternary greensand limestone aquifer was investigated by means of archive data and borehole logging. The aquifer is composed of layers of different lithology, i.e. clay, marl, lime sand, limestone and hardgrounds, which dip slightly towards northwest and are cut by faults. The fault zones, together with a fracture system in the top layers of the aquifer caused by ice pressure, localize zones of high hydraulic conductivity.The hydraulic negative boundaries are found in zones of low hydraulic conductivity mainly within the fault blocks. Both the hydraulic gradient and the hydraulic conductivity decrease with depth in the aquifer. Therefore the main part of the groundwater flow takes place at the upper part of the aquifer. The hydrogeology of the Quaternary aquifers was investigated by means of environmental tritium. Depth of penetration of the tritium has been found and hydraulic properties such as actual velocity, hydraulic conductivity and leakage factors have been estimated. Point values of infiltration are given for two localities to 100-150 mm/year. The groundwater recharge to the limestone aquifers underlying the Quaternary deposits are estimated to between 55-105 mm/year.