Groundwater monitoring

The national groundwater monitoring (GRUMO) is part of the Danish Environmental Protection Agency's National Monitoring Program for Aquatic Environment and Nature (NOVANA). GEUS participates in the monitoring, through GEUS' role as the Topic Centre for Groundwater and Boreholes, which means, among other things, that we provide scientifically based advice regarding monitoring, and prepare and maintain technical guidance documents for the practical field work. In addition, we prepare an annual status report.

All collected data can be found in the public national database Jupiter.

The national monitoring programs were launched as part of the adoption of first Aquatic Environment Plan in 1987, and had two main objectives: First, to monitor the efficiency of the Aquatic Environment Plans and the general agricultural regulations in relation to the aquatic environment's load of nitrogen and phosphorus. Secondly, especially for groundwater monitoring, the purpose was generally to follow the development in the quality and size of the groundwater resource, in order to be able to ensure good quality drinking water for the population of Denmark in the future.

The overall purpose of groundwater monitoring is to:

  • Provide data describing status and trends for both groundwater quality and quantity.
  • Provide data describing the chemical status and trends of groundwater bodies at risk for deterioration of quality or quantity
  • Provide data describing how abstraction and runoff affect the groundwater level in groundwater bodies where there is a risk of not meeting the Water Framework Directive's objective that there must be “sufficient” groundwater (good quantitative condition).
  • Provide data that will help to assess and, if possible, document whether different types of national environmental regulation have the desired effect on groundwater quality and quantity
  • Contribute with data to the development of models - e.g. for use in the work on river basin management plans
  • Contribute data that shed light on whether there is a risk of groundwater being contaminated by substances that have not previously been studied in relation to groundwater contamination.

Monitoring activities

Groundwater quality is monitored through more than 1000 designated monitoring wells (GRUMO wells), where water samples are collected and analysed for a wide range of substances such as nitrate, pesticides, chloride, arsenic, PFAS and other organic pollutants.

In addition to the monitoring in GRUMO wells, the quality of the groundwater is also monitored by the waterworks in the production wells, where a comprehensive number of analyses must be carried out at regular intervals (usually 3-5 years) for the substances included in the Drinking Water Order. As for GRUMO, a large number of substances are analysed, such as nitrate, pesticides, chloride, arsenic, PFAS and other organic pollutants.

The quantity of groundwater is monitored through the National Groundwater Table Sounding Program, where the groundwater level is logged several times a day in approx. 150 boreholes and through annual soundings in the GRUMO wells. In addition, the annual water abstractions of groundwater and surface water is monitored. Abstraction data comes from waterworks, irrigation facilities and other individual abstractors who report the annual pumped water volumes to the public national database Jupiter.


Lærke Thorling
Chief Consultant
Claus Kjøller
Head of Department