Annual nationwide exposure maps for nitrate in drinking water in Denmark from the 1970s until today will be presented based on the findings in Schullehner & Hansen (2014) and additional work on addressing the issue of private well users and estimating missing data. Drinking water supply in Denmark is highly decentralized and fully relying on simple treated groundwater. At the same time, Denmark has an intensive agriculture, making groundwater resources prone to nitrate pollution. Drinking water quality data covering the entire country for over 35 years are registered in the public database Jupiter. In order to create annual maps of drinking water quality, these data had to be linked to 2,852 water supply areas, which were for the first time digitized, collected in one dataset and connected to the Jupiter database. Analyses of the drinking water quality maps showed that public water supplies are extensively registered, while private wells supplying only a few households are neither monitored nor registered in a systematic manner. It was calculated that 5.1% of the Danish population was exposed to elevated nitrate concentrations above 25 mg/L in 2012. Private well users were far more prone to exposure to elevated nitrate concentrations than consumers connected to public supplies. While the fraction exposed to elevated nitrate concentrations amongst public supply users has been decreasing since the 1970s, it has been increasing amongst private well users, leading to the hypothesis that the decrease in nitrate concentrations in drinking water is mainly due to structural changes and not improvement of the groundwater quality as such. It can be seen from the analyses that throughout Denmark there is an adequate exposure contrast, with consumers being exposed to drinking water with nitrate concentrations over a range from as little as below the detection limit up to levels above the drinking water standard of 50 mg/L. Elevated nitrate in drinking water has been associated with several kinds of cancer, e.g. colon cancer, however with ambivalent conclusions. These newly created nitrate concentration maps can now be combined with the exhaustive Danish registers on health and residence, permitting a long-term register based epidemiological study on the health effects of nitrate in drinking water.