Indicator: Nitrate in groundwater

• The European Nitrates Directive, the Groundwater Directive and the German Groundwater and Drinking Water Ordinances require that exceedances of the limit value for nitrate of 50 milligrams per liter be prevented.
• Since 2008, the quality standard has been exceeded every year at almost one in six measuring points.
• The agricultural input of nutrients is the main cause of high nitrate concentrations in groundwater.
• In 2025, the Federal Administrative Court ruled that a national action program must be drawn up to protect water bodies from pollution by nitrates from agricultural sources.

In agriculture crops are given the necessary nitrogen via fertiliser. However, the fertiliser is often not applied correctly for the specific site and use. Excessive nitrogen is leached out and ends up as nitrate in the groundwater and other water bodies. This leads to eutrophication in rivers and lakes (cf. ‘Ecological status of rivers’ and ‘Ecological status of lakes’ indicators), and to nitrogen enrichment and exceedance of the nitrogen threshold in groundwater. Nitrate can be converted to nitrosamines in the human body. This can result in disruption to the oxygen transport in infants (methemoglobinemia). The nitrogen threshold is very rarely exceeded in drinking water. It is complex and expensive to remove nitrate from pipe water in water treatment plants.

The aim of the European Nitrates Directive (EU Directive 91/676/EWG) is to prevent pollution of groundwater by agricultural nitrate inputs. Governments are obliged to develop action plans to prevent nitrate concentrations above 50 mg/l. Since 2016, compliance with the nitrate quality standard has also been a goal of the German Sustainable Development Strategy.

Since 2008, the share of monitoring sites which exceed the quality standard lies between 15 and 19 %. The share of monitoring sites with a nitrate concentration above 25 mg/l has also stagnated since 2008 at around 33–38 %. The share of monitoring points with elevated nitrate concentrations above 25 mg/l has also stagnated at around 33–38% since 2008. Nitrate pollution in groundwater therefore remains too high. However, the increase observed in 2024 is not due to an actual deterioration in the pollution situation, but to changes in the measuring points used for evaluation in the EEA monitoring network.

The central legal instrument for implementing the Nitrates Directive is the German Fertiliser Application Ordinance (Düngeverordnung – DüV). Revisions to the DüV allow, among other things, contaminated areas to be designated separately and stricter management requirements to be imposed there. In addition, Germany has been setting up a national monitoring program since 2019, which will enable annual assessments of nutrient pollution and the effectiveness of the measures taken under the DüV. A monitoring regulation is to form the legal basis for this impact monitoring in the future.

Germany has to send data on the condition of the groundwater to the European Environment Agency (EEA) on a regular basis. The Federal States therefore selected representative monitoring sites to add to the EEA groundwater network. These are reported to the EEA through the German Environment Agency. The indicator compares the monitoring sites where the quality standard is exceeded with the total number of monitoring sites.

More detailed information: 'Grundwasserbeschaffenheit' (in German only).