4. Rating system
Published 15 October 2025
Applies to England and Wales
© Crown copyright 2025
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This publication is available at https://www.gov.uk/government/publications/water-and-sewerage-companies-epa-methodology-for-2026-to-2030/4-rating-system
4.1 Ratings background
A star rating system has been part of the Environmental Performance Assessment (EPA) since it was introduced in the 2011 data year. For the 2026 to 2030 EPA period, an updated rating system will be used which assigns numeric ratings, of 1 (indicating failing performance) to 5 (indicating excellent performance). For data collected from 1 January 2026 onwards, the EPA has expanded and contains additional metrics to previous years. The updated numeric rating system is set out in this section (descriptions, core metric approach and calculations). During this 5 year EPA period (2026 to 2030) the number of live metrics included will increase as shadow metric development work and data assessments for thresholds conclude.
4.2 Rating descriptions
Based on performance across all metrics, EPA numeric ratings are applied to each water and sewerage company. The rating descriptions are:
- 5 – excellent (not live for 2026 and 2027 data years, see note below)
- 4 – good
- 3 – fair
- 2 – requires improvement
- 1 – failing
Note that the 5th rating will become live when red, amber or green (RAG) status thresholds are reinstated for the total pollution incident metric (see section 2.1). Metrics and the rating system are aligned with Water Industry Strategic Environmental Requirements (WISER) expectations. Water and sewerage companies are expected to be rated a 4 consistently. They will exceed expectations if they achieve the new 5th rating when live, which requires green status for all EPA metrics. We regularly review the rating system.
4.3 Core metric approach
The EPA for 2026 to 2030 includes the following core metrics:
- total pollution incidents (not live for 2026 and 2027 data years, until RAG status thresholds are reinstated)
- serious incidents affecting water
- discharge permit compliance with numeric conditions
- Water Industry National Environment Programme (WINEP) and National Environment Programme (NEP) scheme delivery
Core metrics are used in the rating calculations (see section 4.4). To achieve a rating of 3, core metrics must not be red.
4.4 Rating calculations
Numeric ratings are applied to each water and sewerage company after assessment of the live EPA metrics, including core metrics. They are based on RAG status. The numeric rating system adapts to the varying number of metrics during this 5 year EPA period. We have set out the ratings in scenario tables (Appendix 1).
In summary:
- 5 (excellent) – green for all metrics (not live for 2026 and 2027 data years, see note below)
- 4 (good) – green for nearly all metrics, or for 2026 and 2027 data years all or nearly all green metrics (see note below) and no red metrics
- 3 (fair) – mostly green with some amber metrics, or 1 red metric if not a core metric combined with nearly all green metrics
- 2 (requires improvement) – 2 red metrics, or 1 red metric (core or not core) with combinations of amber and green metrics, or mostly amber metrics
- 1 (failing) – 3 or more red metrics
Note that the 5th rating will only become live when the total pollution incidents metric has live RAG thresholds. At any time before this all green metrics would achieve a rating of 4 as the highest attainment.