Sources and regime of streamflow are key factors being responsible for the variability of streamwater quality. However since observed discharge volumes from gauging station records only give the total volume of discharge, the origin or source of the various waters flowing to the stream channel is rarely known. Process oriented water balance simulation models make use of soil and subsoil information to estimate the various components and hence sources of streamflow. In this study calcium and nitrate concentrations of two small adjacent basins are linked to variations in soil moisture fluctuations as simulated with a water balance model. The results show that the basin with deeper soils tends to show also higher variability in streamflow chemistry. In contrast the shallow soils in the other basin results in less variability and a better relation to simulated soil moisture. While mineral concentrations seem to be more directly linked to the quantitative hydrology of the basin, the nutrient behaviour as shown with nitrates needs to be studied more in detail incorporating also biological processes.