5. Summary of EPA differences between the Environment Agency and Natural Resources Wales
Updated 16 June 2026
Applies to England and Wales
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This publication is available at https://www.gov.uk/government/publications/water-and-sewerage-companies-epa-methodology-for-2026-to-2030/5-summary-of-epa-differences-between-the-environment-agency-and-natural-resources-wales
This methodology (section 2) sets out the Environmental Performance Assessment (EPA) metric definitions that we are using.
In some cases, this includes differences in approach between the Environment Agency and Natural Resources Wales.
Total pollution incidents affecting water
Note that incidents reported to the Environment Agency as dry day spill incidents will be recorded on the National Incident Recording System (NIRS) and be reported against this EPA metric from 1 January 2026. Natural Resources Wales will also report dry day spill figures on a yearly basis but will review the frequency and method of reporting.
Abstraction and impounding licence compliance
For the Environment Agency this metric has been a shadow metric (not published) since the start of the 2021 calendar year. Natural Resources Wales has not applied an abstraction and impounding compliance metric as a shadow or live EPA metric and does not intend to in the period 2026 to 2030.
Water environment and security of supply delivery
The Environment Agency has developed a new EPA water resources metric. The Environment Agency and Natural Resources Wales held a joint consultation on the proposed new 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) – see section 2.9. This metric only applies to the 9 water and sewerage companies operating wholly or mainly in England. Natural Resources Wales are not adopting this metric – section 2.10 sets out the Supply Demand Balance Index (SDBI) metric that applies to Dŵr Cymru (Welsh Water) and Hafren Dyfrdwy only.
Supply Demand Balance Index (SDBI)
SDBI was part of the EPA from the financial year ending in March 2022 until the financial year ending in March 2025. This metric was suspended for the financial year ending in March 2026. Natural Resources Wales have reinstated this metric for the financial year ending March 2027 onwards – see section 2.10. This metric only applies to Dŵr Cymru (Welsh Water) and Hafren Dyfrdwy. Section 2.9 sets out the water environment and security of supply metric that only applies to the 9 water and sewerage companies operating wholly or mainly in England.
Reporting methods
Natural Resources Wales may require water and sewerage companies to use reporting templates that reflect the differences in the regulatory frameworks for reporting in Wales. This will also apply to water and sewerage companies not based in Wales that undertake reportable activities in Wales such as application of sludge to land.