Construction of a new regional well-field Kosnica, that should take a major role in water supply, is in progress. Considering importance of a new well-field, the location of recharge areas is of prime concern, as such areas have to be protected in order to preserve good groundwater quality and quantity. Groundwater often consists of a mixture of recharge from surface water (lades or rivers) and local precipitation. It is important to know the proportions of these recharge components in order to increase the sustainable supply of drinking water through bank infiltration, and to prevent drinking water pollution by infiltration of water from a contaminated surface water source. Different recharge components can be identified through the stable isotope compositions of groundwater because of different isotope composition of end components and evaporation in surface water bodies. Isotope techniques are virtually the unavoidable tools which can be used to identify and evaluate present day groundwater recharge.