Environmental performance assessment (EPA) star ratings 2011 to 2024
Published 23 October 2025
Applies to England
© Crown copyright 2025
This publication is licensed under the terms of the Open Government Licence v3.0 except where otherwise stated. To view this licence, visit nationalarchives.gov.uk/doc/open-government-licence/version/3 or write to the Information Policy Team, The National Archives, Kew, London TW9 4DU, or email: psi@nationalarchives.gov.uk.
Where we have identified any third party copyright information you will need to obtain permission from the copyright holders concerned.
This publication is available at https://www.gov.uk/government/publications/water-and-sewerage-companies-in-england-environmental-performance-report-2024/environmental-performance-assessment-epa-star-ratings-2011-to-2024
We introduced the EPA in 2011 as a tool for comparing performance between water companies and across years for several core requirements.
Every 5 years we review how we report on water company environmental performance and review the EPA. We deliberately tighten our metrics over time in response to investment made by the water industry in industry assets and public expectation of better performance. Please see our EPA metric guide for more information on our regulation and how we set targets for water companies. We have shared our EPA methodology for 2021 to 2025 with the water companies.
We have published our annual Environmental performance of the water and sewerage companies in 2024 report and Environmental Performance Assessment results 2011 to 2024. This document provides a summary of the EPA star ratings since 2011. All water companies can achieve 4 stars (industry leading).
From 2011 to 2024:
- 3 water companies have been rated 1 star (poor) – Southern Water 3 times, South West Water 4 times and Thames Water once
- South West Water has consistently been rated 1 star (poor) or 2 stars (requiring improvement), and Southern Water has mostly been rated 1 star or 2 stars
- 5 water companies have achieved 4 stars (industry leading) – all at least twice, but only Severn Trent Water has shown they can achieve this consistently in all of the last 6 years (Table 1)
- sector star ratings ranged between 19 stars and 30 stars (out of a maximum 36) – 2024 has the lowest star rating (Table 1 and Figure 1)
Between 2011 and 2024 we have progressively updated and tightened EPA metrics to reflect environmental expectations. Although it is not straightforward to make a direct comparison across the lifespan of the EPA, we have re-assessed all previous years of data using the 2024 methodology (Figure 1). We do this to indicate if there have been EPA performance improvements over time. The results show an improving trend with some progress in sector star ratings from 11 stars in 2011 to a high of 25 stars in 2023 (out of 36) – however the sector declined to 19 stars in 2024.
Table 1. EPA performance star ratings for the 9 water and sewerage companies 2011 to 2024 (maximum of 4 stars per year)
2011 to 2015 data
| Year | 2011 | 2012 | 2013 | 2014 | 2015 |
|---|---|---|---|---|---|
| Anglian Water | 3 | 3 | 3 | 3 | 3 |
| Northumbrian Water | 2 | 3 | 3 | 3 | 3 |
| Severn Trent Water | 3 | 3 | 4 | 3 | 4 |
| Southern Water | 2 | 2 | 1 | 2 | 3 |
| South West Water | 1 | 2 | 1 | 2 | 1 |
| Thames Water | 3 | 3 | 2 | 3 | 3 |
| United Utilities | 3 | 3 | 3 | 3 | 4 |
| Wessex Water | 4 | 4 | 3 | 3 | 4 |
| Yorkshire Water | 2 | 2 | 3 | 4 | 3 |
| Sector | 23 | 25 | 23 | 26 | 28 |
2016 to 2020 data
| Year | 2016 | 2017 | 2018 | 2019 | 2020 |
|---|---|---|---|---|---|
| Anglian Water | 3 | 3 | 3 | 2 | 3 |
| Northumbrian Water | 2 | 2 | 4 | 2 | 4 |
| Severn Trent Water | 3 | 4 | 3 | 4 | 4 |
| Southern Water | 3 | 3 | 2 | 1 | 2 |
| South West Water | 2 | 2 | 2 | 2 | 2 |
| Thames Water | 2 | 3 | 3 | 3 | 3 |
| United Utilities | 4 | 4 | 3 | 3 | 4 |
| Wessex Water | 4 | 4 | 3 | 4 | 4 |
| Yorkshire Water | 3 | 3 | 2 | 3 | 4 |
| Sector | 26 | 28 | 25 | 24 | 30 |
2021 to 2025 data
| Year | 2021 | 2022 | 2023 | 2024 | 2025 |
|---|---|---|---|---|---|
| Anglian Water | 2 | 2 | 2 | 2 | no data |
| Northumbrian Water | 4 | 3 | 3 | 2 | no data |
| Severn Trent Water | 4 | 4 | 4 | 4 | no data |
| Southern Water | 1 | 2 | 2 | 2 | no data |
| South West Water | 1 | 2 | 2 | 2 | no data |
| Thames Water | 2 | 2 | 2 | 1 | no data |
| United Utilities | 4 | 3 | 4 | 2 | no data |
| Wessex Water | 2 | 2 | 4 | 2 | no data |
| Yorkshire Water | 2 | 3 | 2 | 2 | no data |
| Sector | 22 | 23 | 25 | 19 | no data |
Figure 1. Total EPA star ratings for the 9 water and sewerage companies 2011 to 2024 – using the methodology at the time compared to the 2024 methodology
Chart note: application of the current EPA methodology for 2024 data to previous years of data is subject to caveats due to changes in our expectations and EPA metric definitions.