Environmental quality standards for EU and UK surface water
Environmental quality standards are concentrations in water, sediment or biota not to be exceeded. Check the EU version, matrix and UK instrument.
Environmental quality standards (EQS) are pollutant concentrations in water, sediment or biota that must not be exceeded. In the EU surface-water framework, they protect human health and the environment under the Water Framework Directive, Article 2(35).
For EU surface water, a substance name is not enough to pick a number. You also need the jurisdiction, monitoring matrix, water category and applicable date. The familiar 2013 table now needs a version check: Directive (EU) 2026/805 has revised and expanded the EQS list. UK users must check the relevant domestic instruments rather than assume that the EU amendment changes their limits.
What an EQS measures
An EQS concerns pollutant concentrations in the receiving environment. It is not automatically the concentration that a facility may discharge. The Water Framework Directive defines EQS and emission limit values separately in Articles 2(35) and 2(40).
For a permit assessment, start with the applicable environmental standard. Do not paste that number into an effluent specification. For permit work in England, the Environment Agency provides surface-water pollution risk-assessment guidance.
The EU annex is not a US compliance table. And a surface-water EQS is not a drinking-water standard.
How to read environmental quality standards for surface water
The EQS Directive's Annex I separates several measurement choices. Read the row together with its footnotes and compliance rules, not as an isolated number.
Annual averages and maximum concentrations
AA-EQS means annual-average environmental quality standard. Annex I Part B describes the arithmetic mean of measurements taken at different times during the year at representative monitoring points.
MAC-EQS means maximum allowable concentration. Its compliance test is separate from the annual-average test. Part B permits statistical methods under specified conditions, so one sample does not always decide compliance. Both tests are set out in Annex I Part B, points 1 and 2.
A blank AA cell does not supply an annual-average limit. Don't fill it with the MAC value.
Water, sediment and biota
The amended annex uses µg/L for water, µg/kg wet weight for biota and µg/kg dry weight for sediment where specified. These are different measurement bases. A water result cannot be compared directly with a fish-tissue standard.
Where listed, biota or sediment standards take priority under Article 3(2). Alternative matrices and additional water monitoring for acute risks have conditions under Articles 3(3) and 3(3a). Fish are the default biota taxon unless another is indicated. Fluoranthene, PAHs and bisphenol A use crustacean or mollusc qualifications instead. Check the substance row and Article 3 together before specifying a sampling programme.
Water category and metal measurement basis
"Inland surface waters" covers rivers, lakes and related artificial or heavily modified water bodies. Do not relabel all "other surface waters" as seawater. The framework also covers transitional and coastal waters, with territorial waters included for chemical status. See Annex I footnote 4 and WFD Article 2(1).
The general basis is total concentrations in whole-water samples. Cadmium, lead, mercury and nickel have dissolved-phase or specifically indicated bioavailable provisions. Dissolved means filtration through 0.45 µm, or equivalent pretreatment. That does not make every metal standard a bioavailable standard. Use the exact basis in Annex I Part B, point 3.
The 2013 directive and the updated EU list
Searches for the "environmental quality standards directive 2013" often lead to the historical 45-entry priority-substance table. That table remains useful for a dated comparison. It does not describe the whole newly adopted list.
Directive (EU) 2026/805 replaces Annex I Part A. New entries 46–70 include individual substances and group parameters. Examples include diclofenac, ibuprofen, hormones, neonicotinoids, bisphenol A, silver and a PFAS group parameter. The entry numbers therefore do not mean "70 individual chemicals."
The amendment also moves alachlor, atrazine, carbon tetrachloride, chlorfenvinphos, simazine and trichlorobenzenes into the river-basin-specific-pollutant framework. Their move to Annex II Part C does not mean simple deregulation. Use the published amendment for the full replacement list rather than extending an old spreadsheet.
Which EU dates apply?
Directive (EU) 2026/805 was published on 20 April 2026. Article 5 sets entry into force on the twentieth day after publication, 10 May 2026. Article 4(1) sets national transposition by 21 December 2027. Neither milestone means every revised standard became an immediate domestic requirement on adoption. The amended directive then separates application of the standards from achievement of good status:
| Standards covered | Effect from | Good-status objective |
|---|---|---|
| Revised entries named in Article 3(1a)(iii), including mercury entry 21 | 22 December 2027 | 22 December 2033 |
| New entries 46–70 | 22 December 2027 | 22 December 2039 |
Article 3(1a)(iii)–(iv) names the revised entries as 5, 9, 13, 15, 17, 21, 23, 24, 28, 30, 34, 37, 41 and 43, and the new entries as 46–70. Water Framework Directive exemption conditions qualify the achievement deadlines. Do not use the later good-status objective to assume the standards have no earlier effect.
For new entries, supplementary monitoring is due by 22 December 2027, with preliminary measures due by 22 December 2030. These duties appear in the amended Article 3. In a monitoring programme, record these deadlines separately from the later good-status objective. Do not wait until 2039 to start the monitoring or preliminary measures required by the earlier deadlines.
A EUR-Lex consolidation dated 10 May 2026 helps readers find amended wording. It does not prove national implementation of every standard. The published amending act controls.
Mercury shows why version and matrix matter
Mercury's water maximum stays the same in this comparison, while its biota standard changes:
| EU annex version, entry 21 | Water MAC-EQS, inland and other waters | Biota EQS |
|---|---|---|
| Historical 2013 table | 0.07 µg/L | 20 µg/kg wet weight |
| Adopted 2026 replacement | 0.07 µg/L | 11 µg/kg wet weight |
Neither row supplies a water AA-EQS. The figures are in the historical 2013 annex and the 2026 replacement annex. The revised mercury standard falls within the 22 December 2027 provision and 2033 objective. An unchanged water maximum is not evidence that the whole mercury requirement is unchanged.
Environmental quality standards in the UK
There is no safe shortcut from an EU table to a UK-wide numerical answer. Identify the territory and applicable instrument before selecting a value.
For England and Wales, regulation 6 of the Water Environment (Water Framework Directive) (England and Wales) Regulations 2017 addresses classification and directions. Regulation 2(5) and Schedule 5 modify how referenced directives are read. Schedule 5 shows an amendment dated 27 February 2025. That date does not mean the 2026 EU text has been taken up. Environment Agency chemicals guidance identifies the 2015 England and Wales Standards and Classification Directions. Use that page as a pointer to the domestic directions, not as proof of a complete current numerical schedule.
Scotland has separate Scotland River Basin District Standards Directions 2024 and Solway Tweed Standards Directions 2024. The Scottish Government water-environment legislation listing, updated 11 May 2026, names both. Open the relevant directions and check the schedule and commencement text. A listing is not a numerical schedule.
Northern Ireland has a separate instrument, SR 2015/351. Regulation 4 concerns entries 1–33. Regulation 6 concerns entries 34–45 from 22 December 2018, with a 2027 objective stated in that regulation. Those dates describe that instrument. They do not decide whether the EU 2026 replacement applies. Neither automatic adoption nor automatic exclusion should be assumed.
For each lookup, record the jurisdiction, substance entry, matrix, water category, units and legal version beside the chosen number. Keep application dates separate from good-status objectives.
RegAffairs AI has a public answer on surface-water environmental quality standards.