Large number of groundwater sources is contaminated with nitrates, this problem put many of them out of function. The same problem is present all around the world, as well as in Serbia. The major causes of this problem are agricultural activity and fecal waste waters. By injecting the emulsified vegetable oil in the aquifer we can create anaerobic conditions and stimulate the biodenitrification. In this case vegetable oil is a carbon source and the process of biodegradation is much more efficient than in natural conditions. According to data obtained from the laboratory this technology showed itself very successful. The next step is in situ application and implementation of the technology in existing, natural conditions. 'Ključ' is a ground water aquifer of the Požarevac municipality water supply system; the high concentration of nitrates in its water is a big and permanent problem. For this reason the location of the 'Ključ' aquifer is chosen for the implementation of this technology. This project is not important just for the local interest of the municipality and its citizens; improving this method will open the possibility of saving numerous ground water sources all around the world.