After distinguishing between groundwater containing nitrate and groundwater without nitrate, the first step of the method allows for the classification of groundwater with iron (anoxic) or without iron (oxic). Water types having both iron and nitrate at either low or relatively high concentrations at the same time are classified as 'mixed'. The method can either end here or if needed continue in a second step for mixed samples. The second step considers NH4 and O2 concentrations. After applying the methodology to individual sampling points the results were aggregated to lithological units. The results of these calculations and how the redox potential map was build are described in this report.