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Guidance

Appendix 2: Summary of changes to EPA methodology version A in version B

Updated 16 June 2026

Applies to England and Wales

© Crown copyright 2026

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This publication is available at https://www.gov.uk/government/publications/water-and-sewerage-companies-epa-methodology-for-2026-to-2030/appendix-2-summary-of-changes-to-epa-methodology-version-a-in-version-b

Summary of changes to EPA methodology version A (for EPA period 2026 to 2030) in version B

The original EPA methodology version A for the EPA 2026 to 2030 period was published and shared with companies in October 2025.

Version B, published and shared with companies in March 2026, replaced version A. Version B:

  • updated sections 2, 2.9 and 3 (table 3) to add the water environment and security of supply delivery metric – the Environment Agency plan for the metric to become live for the 2026 data year (based on 1 April 2026 to 31 March 2027 water resources data) following shadow assessment (not published) for the 2025 data year (1 April 2025 to 31 March 2026 water resources data)
  • updated the background to section 2.1 for the total pollution incidents metric now that the guidance for reporting and assessing water industry regulation incidents has been released – also amended wording on source of sewer length data to match the note to table 1, no technical changes
  • updated the frequency of assessment wording in sections 2.4 and 2.5 for the discharge permit compliance metrics to remove the specific date after which final end of year data is extracted – also amended the ‘exclusions’ sub-heading, no technical changes
  • added clarification in sections 2.5, 7.2 and 8.3, particularly relating to when descriptive conditions associated with flow will be part of the permit compliance descriptive condition metric – flow to full treatment (FFT) annual limit requirements are excluded until the FFT metric becomes live from the 2028 data year, and dry weather flow limit requirements are included from the 2026 data year
  • removed reference to development of the storm overflow metric in sections 2.6 and 8.2
  • updated the delivery and tracking expectations subsection with clearer wording in section 2.8 (Water Industry National Environment Programme (WINEP) and National Environment Programme (NEP) in Wales scheme delivery metric) – no technical changes
  • added the water environment and security of supply delivery metric to section 5 (summary of EPA differences between the Environment Agency and Natural Resources Wales) – Natural Resources Wales will confirm their approach at a later date
  • updated section 6.2 to reword what we intend to include as non-EPA performance reporting in the published report
  • updated section 6.3 to remove reference to South West Water and Bristol Water combined reporting
  • added a note to the Appendix 1 numeric rating scenario tables to make clear that the 5th rating is only active and achievable once metric RAG thresholds for the total pollution incidents metric are active
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