Q.01

What does the EU Groundwater Directive require?

The Groundwater Directive (2006/118/EC) puts into practice the groundwater duties of the Water Framework Directive (2000/60/EC). It sets EU-wide groundwater quality standards in Annex I. It requires Member States to set threshold values for other pollutants, and since its 2026 revision it also sets Union-wide threshold values. It requires measures to prevent or limit pollutants getting into groundwater, and to identify and reverse significant and sustained upward pollution trends. The text in force is the consolidated version 02006L0118-20260510 [1].

Approach: I used the Directive's annex tables (Annex I and Annex II Parts B and D) and the consolidated Water Framework Directive, plus the Commission's groundwater policy page. EUR-Lex would not serve the Directive's articles or annex footnotes this time. So the article-level points below come from the Commission page and from the Water Framework Directive's cross-references, and the footnote conditions (marked like "( 7 )" below) could not be read.

1. The core obligations

  • Quality standards and threshold values. According to the Commission, the Directive "sets EU-wide groundwater quality standards for a small number of pollutants in Annex I" and "requires Member States to set threshold values for substances of national concern."
  • Inputs of pollutants. It requires "measures to be taken to prevent or limit the input of pollutants into groundwater." This adds to the Water Framework Directive's own duties:
    • Member States "shall implement the measures necessary to prevent or limit the input of pollutants into groundwater and to prevent the deterioration of the status of all bodies of groundwater" (WFD Article 4(1)(b)(i)) [2].
    • Direct discharges of pollutants into groundwater are prohibited, with listed exceptions such as geothermal reinjection, CO2 storage and mine dewatering (WFD Article 11(3)(j)) [3].
  • Trend reversal. Member States "shall implement the measures necessary to reverse any significant and sustained upward trend" in pollutant concentrations caused by human activity. This is done in line with Article 5 and Annex IV of Directive 2006/118/EC [2].
  • Legal basis. WFD Article 17 required specific EU measures setting criteria for good groundwater chemical status and for identifying trends and starting points for reversing them [4].

2. Good chemical status

A groundwater body has good chemical status when pollutant concentrations meet three conditions [5]:

  • They show no saline or other intrusion.
  • They do not exceed any of the three sets of limits:
    • the Annex I quality standards;
    • the national threshold values under Article 3(1)(b);
    • the Union-wide threshold values under Article 8(3).
  • They do not cause associated surface waters to fail their objectives or significantly damage ecosystems that depend on the groundwater.

How compliance is assessed:

  • Mean values at each monitoring point, aggregated for the whole groundwater body, are used to show compliance.
  • Status is mapped red (poor) or green (good).
  • A black dot marks a significant upward trend and a blue dot marks a reversed trend.
  • Operational monitoring must take place at least once per year, unless longer intervals can be justified.

3. Annex I EU quality standards (current consolidated text)

Values are copied as the source prints them. Only the nitrate entry shows a unit (mg/l); the unit header for the other entries is not in the records I hold.

No.PollutantStandard
1Nitrates50 mg/l [1]
2Pesticide active substances incl. relevant metabolites0,1 (individual); 0,5 (total) [6]
3.1Sum of PFASParametric value in Part B of Annex I to Directive (EU) 2020/2184 [7]
3.2Sum of 4 PFAS0,0044 [8]
4Carbamazepine (298-46-4)2,5 [9]
5Sulfamethoxazole (723-46-6)0,1 [10]
6Primidone (125-33-7)2,5 [11]
7Non-relevant metabolites of pesticides1 or up to 5 (individual); 5 or 12,5 (total), depending on footnotes [12]
8Trichloroethylene + tetrachloroethylene10 (total) [13]

4. Threshold values

  • Annex II Part B lists the 12 pollutants and indicators that Member States must consider when setting national threshold values:
    • Metals: arsenic, cadmium, lead, mercury [14][15][16][17]
    • Ions and nutrients: ammonium, chloride, sulphate, nitrites, phosphorus (total)/phosphates [18][19][20][21][22]
    • Solvents: trichloroethylene, tetrachloroethylene [23][24]
    • Indicator: conductivity [25]
  • Annex II Part D sets one Union-wide threshold value: 2,5 for individual pharmaceutical active substances [26].

5. 2026 revision

  • The Commission says a revision entered into force on 11 May 2026. It aligns the lists "with the latest scientific advice" and, for the first time, addresses "microplastics, indicators of antimicrobial resistance, and sensitive groundwater ecosystems," including certain PFAS.
  • On EUR-Lex the amending act appears as Directive (EU) 2026/805, but I could not open its text.
  • I also could not open the original Directive 2006/118/EC.
  • As a result, I can't quote the article wording, transposition deadlines or footnote conditions here.
Q.02

How does the UK apply it?

The UK has no single groundwater law: each nation implements the Groundwater Directive (2006/118/EC) through its own instruments, regulators and threshold values. In England and Wales the Directive's groundwater requirements were transposed by the Environmental Permitting (England and Wales) Regulations 2016 and the Water Environment (Water Framework Directive) (England and Wales) Regulations 2017. Defra states that "the 2017 Regulations remain as retained EU law" (Defra EPR groundwater guidance, March 2025, para 2.5). Scotland works under the Water Environment and Water Services (Scotland) Act 2003, and Northern Ireland under the Groundwater Regulations (Northern Ireland) 2009.

Approach: The datasets I can search hold no UK groundwater legislation, so this comes from official Defra, GOV.UK, gov.scot, gov.wales and DAERA documents. legislation.gov.uk would not open this time, so I couldn't quote the 2017 Regulations, Schedule 22 to the 2016 Regulations, the 2019 EU Exit amendments or the Northern Ireland and Scottish Regulations directly.

England

The Groundwater (Water Framework Directive) (England) Direction 2016 is the Secretary of State's direction to the Environment Agency "for the implementation of Articles 3, 4 and 5 of the Groundwater Directive". It defines that Directive as 2006/118/EC "as amended by Directive 2014/80/EU".

  • Quality standards (Schedule 1):
    • nitrates: 50 mg/l;
    • pesticide active substances, including relevant metabolites, degradation and reaction products: 0.1 µg/l each and 0.5 µg/l in total.
  • Threshold values (art. 5):
    • The values the Secretary of State has approved are in Table 1, Schedule 5 of the Water Framework Directive (Standards and Classification) Directions (England and Wales) 2015.
    • Where new information shows a value is needed or should be revised, the Agency "must" propose new or revised values for approval.
    • Values must be set under Annex II Parts A and B of the Directive.
    • Schedule 2 lists the minimum pollutants to consider: arsenic, cadmium, lead, mercury, ammonium, chloride, sulphate, nitrites, phosphorus/phosphates, trichloroethylene, tetrachloroethylene and conductivity.
  • Assessing chemical status (art. 6): The Agency must follow the Directive's Article 3(1), 3(6), Article 4(1)-(3), Annex I, Annex II Parts A-B and Annex III paras 1-4.
  • Trends (art. 7):
    • The Agency had to review trend identification and the starting points for trend reversal by 22 December 2020, and must do so again by each sixth anniversary of that date.
    • It must run an additional trend assessment to check that pollution plumes from contaminated sites do not expand.
  • Cross-border river basin districts: In Solway Tweed the Agency must co-operate with SEPA (Scotland). In the Dee and Severn districts it must co-operate with Natural Resources Wales.
  • River basin management plans: Each plan must give the approved threshold values, the status assessment and the starting points for trend reversal (art. 8, Schedule 3).

Permitting (preventing or limiting inputs). Defra's guidance explains how this works in England:

  • It applies in England only. In Wales the December 2010 guidance "should continue to be followed".
  • "It is an offence to cause or knowingly permit a groundwater activity unless authorised by a permit", unless the activity is exempt and complies with the exemption conditions.
  • A "groundwater activity" is a discharge resulting in, or that might lead to, a direct or indirect input of a pollutant to groundwater (Schedule 22, para 3).
  • The Agency may decide an input is not a groundwater activity in some cases: unforeseeable accidents, de minimis inputs, inputs that could only be prevented by measures with greater risks, or inputs that would need disproportionately costly measures.
  • It can serve notices to require a permit or to prohibit an activity (Schedule 22, paras 9-11).
  • Since the 2023 amendment, "pollutant" in England also covers heat and biological entities or micro-organisms. These are treated as non-hazardous pollutants.
  • A small sewage discharge of two cubic metres per day or less of domestic effluent may be exempt if it meets the conditions in Schedule 3 Part 3, including no input within a source protection zone 1.

Wales

Scotland

  • The Scottish Government's policy statement of 13 December 2024 says groundwater threshold values are "set out in the 2024 Standards Directions".
  • SEPA must assess whether the criteria for good status are met and "undertake appropriate investigations" where there is a risk they are not. It classifies on a "one-out, all-out" basis.
  • The Scotland River Basin District (Standards) Directions 2024 direct SEPA on applying these standards. I could not open the PDF, so I can't give Scotland's threshold values.

Northern Ireland

DAERA's groundwater page states:

  • The Groundwater Regulations (Northern Ireland) 2009 "transpose the GWDD".
  • They have been amended in 2009, in 2011 (for the Carbon Capture and Storage Directive 2009/31/EC) and in 2014.
  • The Water (Amendment) (Northern Ireland) (EU Exit) Regulations 2019 keep the transposed water legislation operating after 1 January 2021.

On classification, DAERA's 2021 methodology overview says:

  • Groundwater bodies are classified using UK Technical Advisory Group (UKTAG) guidance, consistent across the UK and with the Republic of Ireland for bodies that cross the border.
  • Status also follows "one out, all out".

The 2026 EU revision

  • The UK texts I opened implement the Directive as it stood before 2026: the England Direction cites it as amended by 2014/80/EU.
  • None of them takes up the EU-level additions from Directive (EU) 2026/805, such as the PFAS and pharmaceutical standards covered in my previous answer.
  • I found no official source saying whether that revision applies in Northern Ireland under the Windsor Framework, so I can't confirm it either way.
Q.03