Data annex: water and sewerage companies in England self-reporting of pollution incidents (category 1 to 3) for 2016 to 2024
Published 18 July 2025
Applies to England
© Crown copyright 2025
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This data annex supports the water and sewerage companies pollution incident report for 2016 to 2024. It presents charts and tables with company specific data and trends for the annual percentage self-reporting of pollution incidents (category 1 to 3).
1. Anglian Water
Anglian Water percentage self-reporting of pollution incidents (category 1 to 3) from sewerage and water supply assets, and trend 2016 to 2024
Anglian Water percentage self-reporting of pollution incidents (category 1 to 3) from sewerage and water supply assets, and 3 year moving average 2016 to 2024
| Year | Percentage self-reporting of pollution incidents (category 1 to 3) |
3 year moving average |
|---|---|---|
| 2016 | 66 | - |
| 2017 | 71 | 66.3 |
| 2018 | 62 | 68.0 |
| 2019 | 71 | 68.7 |
| 2020 | 73 | 71.0 |
| 2021 | 69 | 71.7 |
| 2022 | 73 | 77.0 |
| 2023 | 89 | 83.3 |
| 2024 | 88 | - |
Table note: 3 year moving averages are presented for the middle year of each 3 years. The years 2016 and 2024 are included in calculations but do not have averages presented in the table as they are not middle years.
2. Northumbrian Water
Northumbrian Water percentage self-reporting of pollution incidents (category 1 to 3) from sewerage and water supply assets, and trend 2016 to 2024
Northumbrian Water percentage self-reporting of pollution incidents (category 1 to 3) from sewerage and water supply assets, and 3 year moving average 2016 to 2024
| Year | Percentage self-reporting of pollution incidents (category 1 to 3) |
3 year moving average |
|---|---|---|
| 2016 | 68 | - |
| 2017 | 80 | 77.3 |
| 2018 | 84 | 81.3 |
| 2019 | 80 | 81.7 |
| 2020 | 81 | 83.3 |
| 2021 | 89 | 87.0 |
| 2022 | 91 | 91.3 |
| 2023 | 94 | 91.7 |
| 2024 | 90 | - |
Table note: 3 year moving averages are presented for the middle year of each 3 years. The years 2016 and 2024 are included in calculations but do not have averages presented in the table as they are not middle years.
3. Severn Trent Water
Severn Trent Water percentage self-reporting of pollution incidents (category 1 to 3) from sewerage and water supply assets, and trend 2016 to 2024
Severn Trent Water percentage self-reporting of pollution incidents (category 1 to 3) from sewerage and water supply assets, and 3 year moving average 2016 to 2024
| Year | Percentage self-reporting of pollution incidents (category 1 to 3) |
3 year moving average |
|---|---|---|
| 2016 | 79 | - |
| 2017 | 80 | 79.3 |
| 2018 | 79 | 79.0 |
| 2019 | 78 | 77.7 |
| 2020 | 76 | 78.0 |
| 2021 | 80 | 81.0 |
| 2022 | 87 | 85.3 |
| 2023 | 89 | 88.7 |
| 2024 | 90 | - |
Table note: 3 year moving averages are presented for the middle year of each 3 years. The years 2016 and 2024 are included in calculations but do not have averages presented in the table as they are not middle years.
4. Southern Water
Southern Water percentage self-reporting of pollution incidents (category 1 to 3) from sewerage and water supply assets, and trend 2016 to 2024
Southern Water percentage self-reporting of pollution incidents (category 1 to 3) from sewerage and water supply assets, and 3 year moving average 2016 to 2024
| Year | Percentage self-reporting of pollution incidents (category 1 to 3) |
3 year moving average |
|---|---|---|
| 2016 | 71 | - |
| 2017 | 70 | 74.7 |
| 2018 | 83 | 80.0 |
| 2019 | 87 | 86.0 |
| 2020 | 88 | 88.3 |
| 2021 | 90 | 89.3 |
| 2022 | 90 | 83.0 |
| 2023 | 69 | 80.3 |
| 2024 | 82 | - |
Table note: 3 year moving averages are presented for the middle year of each 3 years. The years 2016 and 2024 are included in calculations but do not have averages presented in the table as they are not middle years.
5. South West Water
South West Water percentage self-reporting of pollution incidents (category 1 to 3) from sewerage and water supply assets, and trend 2016 to 2024
South West Water percentage self-reporting of pollution incidents (category 1 to 3) from sewerage and water supply assets, and 3 year moving average 2016 to 2024
| Year | Percentage self-reporting of pollution incidents (category 1 to 3) |
3 year moving average |
|---|---|---|
| 2016 | 64 | - |
| 2017 | 68 | 69.7 |
| 2018 | 77 | 73.7 |
| 2019 | 76 | 75.7 |
| 2020 | 74 | 72.7 |
| 2021 | 68 | 73.3 |
| 2022 | 78 | 76.0 |
| 2023 | 82 | 80.7 |
| 2024 | 82 | - |
Table note: 3 year moving averages are presented for the middle year of each 3 years. The years 2016 and 2024 are included in calculations but do not have averages presented in the table as they are not middle years.
6. Thames Water
Thames Water percentage self-reporting of pollution incidents (category 1 to 3) from sewerage and water supply assets, and trend 2016 to 2024
Thames Water percentage self-reporting of pollution incidents (category 1 to 3) from sewerage and water supply assets, and 3 year moving average 2016 to 2024
| Year | Percentage self-reporting of pollution incidents (category 1 to 3) |
3 year moving average |
|---|---|---|
| 2016 | 67 | - |
| 2017 | 73 | 72.0 |
| 2018 | 76 | 75.7 |
| 2019 | 78 | 72.3 |
| 2020 | 63 | 68.7 |
| 2021 | 65 | 67.3 |
| 2022 | 74 | 71.7 |
| 2023 | 76 | 75.0 |
| 2024 | 75 | - |
Table note: 3 year moving averages are presented for the middle year of each 3 years. The years 2016 and 2024 are included in calculations but do not have averages presented in the table as they are not middle years.
7. United Utilities
United Utilities percentage self-reporting of pollution incidents (category 1 to 3) from sewerage and water supply assets, and trend 2016 to 2024
United Utilities percentage self-reporting of pollution incidents (category 1 to 3) from sewerage and water supply assets, and 3 year moving average 2016 to 2024
| Year | Percentage self-reporting of pollution incidents (category 1 to 3) |
3 year moving average |
|---|---|---|
| 2016 | 75 | - |
| 2017 | 82 | 78.7 |
| 2018 | 79 | 83.7 |
| 2019 | 90 | 83.7 |
| 2020 | 82 | 84.3 |
| 2021 | 81 | 83.7 |
| 2022 | 88 | 87.7 |
| 2023 | 94 | 90.7 |
| 2024 | 90 | - |
Table note: 3 year moving averages are presented for the middle year of each 3 years. The years 2016 and 2024 are included in calculations but do not have averages presented in the table as they are not middle years.
8. Wessex Water
Wessex Water percentage self-reporting of pollution incidents (category 1 to 3) from sewerage and water supply assets, and trend 2016 to 2024
Wessex Water percentage self-reporting of pollution incidents (category 1 to 3) from sewerage and water supply assets, and 3 year moving average 2016 to 2024
| Year | Percentage self-reporting of pollution incidents (category 1 to 3) |
3 year moving average |
|---|---|---|
| 2016 | 76 | - |
| 2017 | 78 | 76.0 |
| 2018 | 74 | 79.0 |
| 2019 | 85 | 81.3 |
| 2020 | 85 | 86.7 |
| 2021 | 90 | 89.0 |
| 2022 | 92 | 92.0 |
| 2023 | 94 | 92.7 |
| 2024 | 92 | - |
Table note: 3 year moving averages are presented for the middle year of each 3 years. The years 2016 and 2024 are included in calculations but do not have averages presented in the table as they are not middle years.
9. Yorkshire Water
Yorkshire Water percentage self-reporting of pollution incidents (category 1 to 3) from sewerage and water supply assets, and trend 2016 to 2024
Yorkshire Water percentage self-reporting of pollution incidents (category 1 to 3) from sewerage and water supply assets, and 3 year moving average 2016 to 2024
| Year | Percentage self-reporting of pollution incidents (category 1 to 3) |
3 year moving average |
|---|---|---|
| 2016 | 79 | - |
| 2017 | 83 | 78.3 |
| 2018 | 73 | 76.3 |
| 2019 | 73 | 75.7 |
| 2020 | 81 | 73.3 |
| 2021 | 66 | 74.7 |
| 2022 | 77 | 72.7 |
| 2023 | 75 | 76.7 |
| 2024 | 78 | - |
Table note: 3 year moving averages are presented for the middle year of each 3 years. The years 2016 and 2024 are included in calculations but do not have averages presented in the table as they are not middle years.