Due to the special landscape structure of the Upper-Backa area at both sides of the border the drinking water supply can either be based on large wellfields of waterworks, or the water can be taken from individual abstractions (drilled wells), tapping the local water body. In drinking water capture zones the quality of the supplied water might fall short of the requirements set by the EU limit values for various reasons. Potential water quality problems might be originated from natural sources or human pollution spreading in the continuous subsurface water body located at both sides of the border. Contamination can also be caused by poor technical status of the operational wells or the individual drilled abstractions, letting the more contaminated unconfined groundwaters to seep down through the aquitard to the older, cleaner lower aquifers. The area of this subsurface confined water body is rather large (nearly 5 000 km2) shared by the two countries in similar proportion. Groundwater pollution does not respect political borders, contamination from one country would inevitably spread to the other country, therefore cross-border action is necessary to maintaining the drinking water safety of this large region.For this aim the first task is to gather appropriate information on the water quality status of the transboundary water body, then the technical status of wells andabstractions should be assessed, finally the actions required to reach the good status of the water body shall be determined. In order to achieve these objectives, data collection, data base development, sample collection, laboratory analysis, evaluation of the results and elaboration of action plan are planned in the proposed one year long project. Achievements: Due to the special structure of terrain in the Upper Bačka area on both sides of the border, the drinking water supply can either come from large wellfields of waterworks, or the water can be taken from individual abstractions (drilled wells). In the drinking water well capture zones, the quality of the supplied water might fail to satisfy the requirements set by the EU limit values for various reasons. Potential water quality problems may originate from natural sources or human pollution spreading in the continuous groundwater body located on both sides of the border. Contamination can also be caused by poor technical status of the operating wells or the individual drilled abstractions, letting more contaminated unconfined groundwater to seep down through the aquitard to the older, cleaner, lower aquifers. Over the course of the DriWAS project, the four organisations from two countries jointly managed to gather appropriate information on the water quality status of the trans-boundary water body, followed by the assessment of the technical status of wells and abstractions, and finally the etermination of the actions required to raise the condition of the water body to a suitable level. This was achieved by means of data collection, database development, sample collection, laboratory analysis, evaluation of the results, and elaboration of action plans. The area of the confined subsurface water body in this region is rather large, shared in almost equal measure by the two countries. Groundwater pollution does not stop at the state borders, so contamination from one country inevitably spreads to the other, making cross-border action the only solution for maintaining the safety of drinking water in this large region.