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.
• Extensive changes to the fertilizer legislation have allowed the designation of particularly polluted areas since 2023, combined with stricter management requirements and the introduction of a national monitoring program.
• The agricultural input of nutrients is the main cause of high nitrate concentrations in groundwater.

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 central legal instrument for implementing the Nitrates Directive is the German Fertiliser Application Ordinance. It defines "good professional practice in fertilisation" and specifies how the risks associated with fertilisation are to be minimised. It is an essential component of the national action plan. In February 2020, the federal government presented a new draft that had been agreed with the EU and which was approved by the Bundesrat on 27 March 2020: It has been legally effective since 1 May 2020.

On 21 June 2018, the European Court of Justice had found Germany guilty of violating the EU Nitrates Directive (Rs. C-543/16) because the directive had not been implemented adequately and the measures taken so far were not sufficient to achieve a significant reduction in nitrate pollution. As a result, Germany has repeatedly revised its fertilizer legislation, in particular the Fertilizer Ordinance (DüV). It now allows polluted areas to be designated separately and stricter management requirements to be enforced there. In addition, Germany has been setting up a national monitoring program since 2019, which is intended to enable annual statements to be made on nutrient pollution and the effect of the measures under the DüV. A new monitoring regulation is to form the legal basis for this impact monitoring in the future. The EU infringement proceedings against Germany were discontinued on June 1, 2023. The extent to which the additional measures now implemented are sufficient to reduce nitrate pollution of groundwater will be shown by measurements in the coming years.

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).