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Protection of groundwater against pollution

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Protection of groundwater against pollution

The European Union is establishing a framework to prevent and control groundwater pollution. This includes procedures for assessing the chemical status of groundwater and measures to reduce levels of pollutants.


Directive 2006/118/EC of the European Parliament and of the Council of 12 December 2006 on the protection of groundwater against pollution and deterioration.


This Directive is designed to prevent and combat groundwater pollution. Its provisions include:

  • criteria for assessing the chemical status of groundwater;
  • criteria for identifying significant and sustained upward trends in groundwater pollution levels, and for defining starting points for reversing these trends;
  • preventing and limiting indirect discharges (after percolation through soil or subsoil) of pollutants into groundwater.

Groundwater chemical status

Groundwater is considered to have a good chemical status when:

  • measured or predicted nitrate levels do not exceed 50 mg/l, while those of active pesticide ingredients, their metabolites and reaction products do not exceed 0.1 µg/l (a total of 0.5 µg/l for all pesticides measured);
  • the levels of certain high-risk substances are below the threshold values set by Member States; at the very least, this must include ammonium, arsenic, cadmium, chloride, lead, mercury, sulphate, trichloroethylene and tetrachloroethylene;
  • the concentration of any other pollutants conforms to the definition of good chemical status as set out in Annex V to the Water Framework Directive (EN);
  • if a value set as a quality standard or a threshold value is exceeded, an investigation confirms, among other things, that this does not pose a significant environmental risk.

The presence of pollutants in groundwater

By 22 December 2008, Member States must set a threshold value for each pollutant identified in any of the bodies of groundwater within their territory considered to be at risk. As a minimum, Member States must establish threshold values for ammonium, arsenic, cadmium, chloride, lead, mercury, sulphate, trichloroethylene and tetrachloroethylene. For each pollutant on the list, information (as defined in Annex III to this Directive) must be provided on the groundwater bodies characterised as being at risk, as well as on how the threshold values were set. These threshold values must be included in the River Basin District Management Plans provided for under the Water Framework Directive. By 22 December 2009, the Commission will draw up a report based on the information provided by Member States.

Member States must identify any significant and sustained upward trend in levels of pollutants found in bodies of groundwater. In order to do so, they must establish a monitoring programme in conformity with Annex IV to this Directive.

Taking account of Annex IV to the Directive, Member States must also define a starting point for reversing these upward trends. Trend reversals will focus on concentrations which pose a risk to associated aquatic ecosystems, dependent terrestrial ecosystems, human health or legitimate uses of the water environment.

Preventing and limiting discharges of pollutants

The programme of measures drawn up for each river basin district under the Water Framework Directive must include preventing indirect discharges of all pollutants, in particular those hazardous substances mentioned in Points 1 to 6 of Annex VIII to the Water Framework Directive (List I of Directive 80/68/EEC), as well as the substances mentioned in Points 7 to 9 of the Annex (List II of Directive 80/68/EEC), when deemed to be hazardous. Furthermore, pollutants not listed as hazardous must also be limited if they pose a real or potential risk of pollution.

Except in those cases where other Community legislation establishes more stringent requirements, preventive measures may exclude, among other things, the results of authorised direct discharges, pollutants present in such small quantities that they pose no risk, the results of accidents or natural disasters, or pollutants resulting from discharges which, for technical reasons, the competent authorities consider to be impossible to prevent or limit without resorting to measures that would increase the risk to human health or to the environment or to measures that would be disproportionately costly.


The Water Framework Directive, adopted in October 2000, stated that measures would be adopted to prevent and control groundwater pollution. These measures are set out in this Directive, which is why it is known as the "daughter Directive" to the Framework Directive. Furthermore, in 2013 the Water Framework Directive will repeal Directive 80/68/EEC on the protection of groundwater against pollution by certain dangerous substances. This Directive is designed to protect groundwater and fill the legislative gap following the repeal of Directive 80/68/EEC.

Groundwater protection is a priority in EU environmental policy for several reasons:

  • once contaminated, groundwater is harder to clean than surface water and the consequences can last for decades;
  • as groundwater is frequently used for the abstraction of drinking water, for industry and for agriculture, groundwater pollution can endanger human health and threaten those activities;
  • groundwater provides the base flow for many rivers (it can provide up to 90% of the flow in some watercourses) and can thus affect the quality of surface water systems;
  • it also acts as a buffer through dry periods, and is essential for maintaining wetlands.



Entry into force - Date of expiry

Deadline for transposition in the Member States

Official Journal

Directive 2006/118/EC



OJ L 372, 27.12.2006

Last updated: 10.05.2007