Due to potential adverse public health effects, standards for a maximum acceptable concentration of nitrates in drinking water have already been established in many parts of the world. However, nitrate levels in many drinking water supplies are on a rising trend. In this context, a 1991 European Directive concerning the "protection of waters against pollution caused by nitrates from agricultural sources" set ambitious goals aimed at preventing pollution by nitrates with expected benefits both for nitrate levels in drinking water sources, including groundwater, and eutrophication, etc.