The Moldavian Plateau and Plain have few drinking water sources (the case of Iaşi and Vaslui Counties). The main type of fresh water sources are groundwater and surface water. The Moldavian Plateau rural settlements are affected the most by the lack of viable, unpolluted water sources to ensure a volume able to cover the consumers’ demand. The pollution phenomenon induced by the non-availability of rural sewerage systems and also by the settlements’ areas foundation rocks have decreased the groundwater and surface water sources quality parameters. The adduction, transport and distribution networks of water supply systems are affected by the „water loss“ phenomenon. Water management in a transmission and distribution network must correlate the number of water sources, available volume, acceptable quality parameters and inherent water losses from networks with the consumers’ demands. The optimisation of water management in a given geographic space has led to the establishment of „regional water supply systems“. This process relies on the minimisation of water losses. The case study carried out in Iaşi County shows the importance of the regional water supply system development through optimal exploitation of Moldavian Plateau and Plain water sources.