This thesis is based on expansion and renovation of source "Lobor" as a part of a larger water supply system of Krapinsko - zagorska county. Main task of expansion and renovation of source "Lobor" is to increase volume of water intake in this specific area because of expected increase in need for water in upcoming years. Developed idea for increasing water intake is based on pumping of groundwater reserves. As a part of renovation of the source a hydraulic calculation has been carried out for building a new pipeline system on the source area and for supporting structures necessary for its proper functioning. An idea for a new water reservoir and accompanying chlorine purification structure is given as well. To compose a project of expansion and development of the source its important to collect information about demographics of the area, water needs of the population, now and in future, information about buildings and structures on the source area, information collected from research about hydrogeological conditions and groundwater reserves of the area. Following the analysis of collected data on residents need for water, steps in development of water supply system of the observed area and information from borehole research carried in the area, comes hydraulic calculation necessary for renovation of pipeline system and selection of suitable pumping systems. Technical specification about structures and construction actions is given alongside schemes and drafts.