Water and sewerage companies in England: pollution incident report for 2016 to 2024
Published 18 July 2025
Applies to England
© Crown copyright 2025
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1. Foreword
This report sets out the persistently poor pollution incident performance of the 9 water and sewerage companies in England. At a time when there is unprecedented interest in the health of our rivers, lakes and seas, the water industry must do much more to prevent pollution from occurring and to respond rapidly when it does. We at the Environment Agency are here to hold them to account.
Our expectations for the sector for 2020 to 2025 are set out in our Water Industry Strategic Environmental Requirements (WISER). There should have been a trend to zero serious pollution incidents, a reduction in all pollution incidents and high levels of self-reporting. In this report we look both at sector numbers and how each water company has performed since 2016. It is evident that there has been a systemic failure by some companies to meet these targets.
The increased monitoring we require of water company assets and interest from the public and water stakeholders has pushed incidents and their impacts into the spotlight. However, this report shows a further upturn in pollution incidents in 2024. This is simply unacceptable. Water companies must act urgently, by understanding and learning from the root causes of incidents, better maintaining their assets in the short term and improving asset health and resilience in the long term. They need robust management systems which prevent similar occurrences across their operations. And when something goes wrong, they need to tell us as quickly as possible. Water companies operating in England have a record £98 billion to spend between 2025 and 2030, of which £46 billion is wastewater. This includes maintenance of assets, so we expect the companies to deliver on their performance commitments.
We have made significant changes to tighten our regulation of the water industry and ensure companies are held to account. With a dedicated larger workforce we have carried out an increased number of inspections (4,000 in 2024/25 and 10,000 planned in 2025/26). Our regulation and enforcement officers are uncovering and acting on failures to comply with environmental law.
The Water (Special Measures) Act 2025 (WSMA) grants Ofwat new powers. They have implemented a rule requiring water companies to prohibit the payment of performance related pay, such as bonuses, to water bosses if they fail to meet certain standards, including on the environment. Data included in this report on the most serious category 1 pollution incidents were shared with Ofwat to support their monitoring of compliance with this new rule. The Act also requires companies to produce annual pollution incident reduction plans to address the root cause of persistent problems and prevent pollution incidents. We will continue to work closely with our fellow regulators to hold companies to account to deliver the environmental improvements for people, communities and wildlife.
Our annual water company environmental performance report on wider aspects of environmental performance in 2024 will be published in October 2025. But there is no need for the water industry to wait. We expect rapid action to turn around intolerable pollution incident performance.
Helen Wakeham, Director of Water, Environment Agency
2. Introduction
This report is about the 9 water and sewerage companies (called ‘water companies’ or collectively ‘the sector’ within this report) operating mainly in England that provide clean drinking water (water supply) and wastewater (sewerage) services. Water supply only companies, and companies providing localised water supply and sewerage services are not covered in this report.
This report presents water company pollution incident data for 2016 to 2024 including any incident affecting the water environment from either sewerage or water supply assets. We provide an analysis of both sector and company specific data in this report and the supporting data annexes.
Pollution incidents lead to the release of harmful substances into air, land or water, and some can cause significant harm to the environment. We categorise all incidents based on their impact. Incidents are assessed as having a major (category 1), significant (category 2), or minor (category 3) impact on the water environment.
We expect water companies to report pollution incidents to us in a timely way before others do. Without a rapid response, the impact of pollution can escalate and the opportunity for mitigation measures can be lost.
3. Water Industry Strategic Environmental Requirements – pollution incident performance expectations
In October 2017 we set out our performance expectations for 2020 to 2025 (Water Industry Strategic Environmental Requirements, WISER) describing environmental, resilience and flood risk obligations. Water companies were required to take these into account when developing their business plans for the Asset Management Plan period 2020 to 2025 (AMP7).
We have the following expectations of water companies that are directly relevant to pollution incidents for 2020 to 2025:
- trend to minimise all pollution incidents (category 1 to 3) by 2025 – there should be at least a 40% reduction compared to numbers of incidents recorded in 2016
- serious pollution (category 1 and 2) incidents must trend towards zero
- high levels of self-reporting of pollution incidents with at least 80% of incidents self-reported by 2025 and more than 90% of incidents self-reported for just sewage treatment works (STW) and pumping stations (PS) combined
This report covers company and sector progress against these expectations for 2020 to 2025 – including serious pollution incidents (section 4), all pollution incidents (section 5) and self-reporting of pollution incidents (section 6). We also include information on pollution interventions (section 7) which explains actions being taken related to pollution incidents.
4. Serious pollution incident performance
Serious pollution incidents have a negative impact on the environment. This is why we are extremely concerned about the 60% increase in serious incidents between 2023 and 2024. This deterioration is not acceptable and means the sector is failing to meet our WISER performance expectation to trend to zero. The high number in 2024 was mainly due to the performance of 3 water companies resulting in a very polarised performance picture across the sector again – some companies have more to do than others.
4.1 Performance facts for 2016 to 2024
For serious pollution incidents in 2024:
- the sector total was 75 – this is a significant increase (60%) from 47 in 2023
- the majority (61 out of 75, 81%) were from the assets of 3 water companies – Thames Water (33), Southern Water (15) and Yorkshire Water (13)
- the numbers for 4 companies (Southern Water, Thames Water, United Utilities and Yorkshire Water) were statistically significant – this means they were higher than their average for the period
- Thames Water had the highest number – more than double since 2023, increasing from 14 to 33
- numbers increased for 6 water companies compared to 2023 (Severn Trent Water, Southern Water, South West Water, Thames Water, United Utilities and Yorkshire Water)
- 2 water companies had fewer serious incidents compared to 2023 (Anglian Water, Wessex Water)
- Northumbrian Water and Wessex Water had zero
- there were 11 category 1 incidents from 5 water companies – 7 from Thames Water and 1 each from Anglian Water, Southern Water, United Utilities, Yorkshire Water
- most continue to be from foul sewers (22) followed by STW (20) and rising mains (15) – together representing 57 out of 75 (76%) of all serious pollution incidents
For serious pollution incidents in the period 2016 to 2024:
- sector numbers have been unacceptably high throughout but the total in 2024 was the highest – 32% higher than 2016 (from 57 in 2016 to 75 in 2024)
- numbers have not declined which is contrary to the WISER expectation to trend to zero
- Thames Water have been the worst performing company with the highest number of incidents and highest annual average
- Southern Water and Thames Water performance trend deteriorated
- numbers have been variable for 4 companies (South West Water, United Utilities, Wessex Water, Yorkshire Water)
- numbers have slowly improved for Anglian Water but are still a long way from zero
- numbers have improved towards zero for 2 companies (Northumbrian Water, Severn Trent Water)
- only 4 companies (Northumbrian Water, Severn Trent Water, United Utilities and Wessex Water) have ever achieved zero serious pollution incidents – Northumbrian Water and United Utilities for 3 of the 9 years
- Northumbrian Water have had zero incidents for the last 3 years in a row, achieving our WISER performance expectation
- the number of the most serious, category 1, has not improved
- the majority are from sewerage assets, with numbers worsening for rising mains and variable for foul sewers, PS and STW – we expected improvement at STW and PS as these permitted assets normally have alarms or staff on site
4.2 Performance data for 2016 to 2024
4.2.1 Number of serious pollution incidents (category 1 and 2) from sewerage and water supply assets, and trend for the 9 water and sewerage companies 2016 to 2024
Chart note: a statistical assessment (using the Pearson correlation coefficient) has been applied to annual data – this identifies the years 2021 and 2024 to be significantly higher than the average for the data period 2016 to 2024.
4.2.2 Annual number of serious pollution incidents (category 1 and 2) from sewerage and water supply assets for each of the 9 water and sewerage companies 2016 to 2024
| Water company | 2016 | 2017 | 2018 | 2019 | 2020 | 2021 | 2022 | 2023 | 2024 |
|---|---|---|---|---|---|---|---|---|---|
| Anglian Water | 11 | 19 | 10 | 14 | 11 | 14 | 11 | 11 | 7 |
| Northumbrian Water | 9 | 3 | 2 | 3 | 4 | 1 | 0 | 0 | 0 |
| Severn Trent Water | 7 | 2 | 7 | 4 | 2 | 4 | 1 | 0 | 1 |
| Southern Water | 3 | 4 | 7 | 7 | 4 | 12 | 5 | 13 | 15 |
| South West Water | 4 | 3 | 2 | 1 | 3 | 8 | 2 | 2 | 4 |
| Thames Water | 10 | 10 | 9 | 15 | 13 | 12 | 17 | 14 | 33 |
| United Utilities | 4 | 2 | 1 | 0 | 0 | 1 | 0 | 1 | 2 |
| Wessex Water | 2 | 3 | 4 | 1 | 4 | 5 | 5 | 1 | 0 |
| Yorkshire Water | 7 | 6 | 14 | 7 | 3 | 5 | 3 | 5 | 13 |
| Sector total | 57 | 52 | 56 | 52 | 44 | 62 | 44 | 47 | 75 |
| Sector trend (3 year moving average) | - | 55.0 | 53.3 | 50.7 | 52.7 | 50.0 | 51.0 | 55.3 | - |
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.
4.2.3 Annual number of serious pollution incidents (category 1 and 2) from sewerage and water supply assets for each of the 9 water and sewerage companies 2016 to 2024 with range and average (mean)
4.2.4 Lowest, highest and average (mean) annual number of serious pollution incidents (category 1 and 2) from sewerage and water supply assets for each of the 9 water and sewerage companies 2016 to 2024
| Water company | Lowest in range | Highest in range | Average (mean) |
|---|---|---|---|
| Anglian Water | 7 | 19 | 12.0 |
| Northumbrian Water | 0 | 9 | 2.4 |
| Severn Trent Water | 0 | 7 | 3.1 |
| Southern Water | 3 | 15 | 7.8 |
| South West Water | 1 | 8 | 3.2 |
| Thames Water | 9 | 33 | 14.8 |
| United Utilities | 0 | 4 | 1.2 |
| Wessex Water | 0 | 5 | 2.8 |
| Yorkshire Water | 3 | 14 | 7.0 |
| Sector total | 23 | 114 | 54.3 |
4.2.5 Annual number of serious pollution incidents (category 1 and 2) from sewerage and water supply assets for each of the 9 water and sewerage companies 2016 to 2024 and trend
Chart note: annual numbers and 3 year moving averages are provided for each water company in the supporting data annex for serious pollution incidents.
4.2.6 Annual number of category 1 and category 2 pollution incidents from sewerage and water supply assets for the 9 water and sewerage companies 2016 to 2024
| Year | Number of category 1 incidents | Number of category 2 incidents |
|---|---|---|
| 2016 | 9 | 48 |
| 2017 | 11 | 41 |
| 2018 | 9 | 47 |
| 2019 | 11 | 41 |
| 2020 | 3 | 41 |
| 2021 | 8 | 54 |
| 2022 | 6 | 38 |
| 2023 | 7 | 40 |
| 2024 | 11 | 64 |
4.2.7 Annual number of category 1 pollution incidents from sewerage and water supply assets for each of the 9 water and sewerage companies 2016 to 2024
| Water company | 2016 | 2017 | 2018 | 2019 | 2020 | 2021 | 2022 | 2023 | 2024 |
|---|---|---|---|---|---|---|---|---|---|
| Anglian Water | 1 | 1 | 1 | 2 | 0 | 1 | 0 | 0 | 1 |
| Northumbrian Water | 2 | 2 | 0 | 1 | 1 | 0 | 0 | 0 | 0 |
| Severn Trent Water | 2 | 1 | 0 | 2 | 0 | 1 | 0 | 0 | 0 |
| Southern Water | 0 | 0 | 1 | 3 | 0 | 3 | 2 | 4 | 1 |
| South West Water | 1 | 1 | 1 | 0 | 0 | 0 | 0 | 0 | 0 |
| Thames Water | 2 | 3 | 0 | 2 | 2 | 1 | 3 | 1 | 7 |
| United Utilities | 0 | 0 | 1 | 0 | 0 | 1 | 0 | 1 | 1 |
| Wessex Water | 0 | 1 | 2 | 1 | 0 | 1 | 1 | 0 | 0 |
| Yorkshire Water | 1 | 2 | 3 | 0 | 0 | 0 | 0 | 1 | 1 |
| Sector total | 9 | 11 | 9 | 11 | 3 | 8 | 6 | 7 | 11 |
4.2.8 Annual number of category 2 pollution incidents from sewerage and water supply assets for each of the 9 water and sewerage companies 2016 to 2024
| Water company | 2016 | 2017 | 2018 | 2019 | 2020 | 2021 | 2022 | 2023 | 2024 |
|---|---|---|---|---|---|---|---|---|---|
| Anglian Water | 10 | 18 | 9 | 12 | 11 | 13 | 11 | 11 | 6 |
| Northumbrian Water | 7 | 1 | 2 | 2 | 3 | 1 | 0 | 0 | 0 |
| Severn Trent Water | 5 | 1 | 7 | 2 | 2 | 3 | 1 | 0 | 1 |
| Southern Water | 3 | 4 | 6 | 4 | 4 | 9 | 3 | 9 | 14 |
| South West Water | 3 | 2 | 1 | 1 | 3 | 8 | 2 | 2 | 4 |
| Thames Water | 8 | 7 | 9 | 13 | 11 | 11 | 14 | 13 | 26 |
| United Utilities | 4 | 2 | 0 | 0 | 0 | 0 | 0 | 0 | 1 |
| Wessex Water | 2 | 2 | 2 | 0 | 4 | 4 | 4 | 1 | 0 |
| Yorkshire Water | 6 | 4 | 11 | 7 | 3 | 5 | 3 | 4 | 12 |
| Sector total | 48 | 41 | 47 | 41 | 41 | 54 | 38 | 40 | 64 |
4.2.9 Annual number of serious (category 1 and category 2) pollution incidents from sewerage and water supply assets for each of the 9 water and sewerage companies 2016 to 2024 and trend
Chart note: data for surface water outfalls, water treatment works (water supply), storm tanks and other water industry premises is not plotted due to low numbers compared to other asset types.
4.2.10 Annual number of serious (category 1 and category 2) pollution incidents from sewerage and water supply assets for the 9 water and sewerage companies 2016 to 2024
| Asset type | 2016 | 2017 | 2018 | 2019 | 2020 | 2021 | 2022 | 2023 | 2024 |
|---|---|---|---|---|---|---|---|---|---|
| Foul sewer | 19 | 16 | 15 | 15 | 16 | 19 | 18 | 16 | 22 |
| Sewage treatment works | 11 | 9 | 17 | 14 | 12 | 16 | 7 | 14 | 20 |
| Rising main | 4 | 4 | 7 | 5 | 6 | 13 | 11 | 11 | 15 |
| Pumping station | 10 | 4 | 6 | 9 | 3 | 12 | 3 | 4 | 11 |
| Water distribution system (water supply) | 2 | 12 | 7 | 3 | 5 | 1 | 2 | 1 | 2 |
| Combined sewer overflow | 7 | 2 | 2 | 3 | 2 | 1 | 1 | 1 | 2 |
| Water treatment works (water supply) | 2 | 2 | 1 | 1 | 0 | 0 | 0 | 0 | 2 |
| Surface water outfall | 1 | 2 | 1 | 2 | 0 | 0 | 1 | 0 | 0 |
| Storm tank | 1 | 1 | 0 | 0 | 0 | 0 | 1 | 0 | 1 |
| Other water industry premises | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| Sector total | 57 | 52 | 56 | 52 | 44 | 62 | 44 | 47 | 75 |
4.2.11 The 3 year moving average for annual number of serious (category 1 and category 2) pollution incidents from sewerage and water supply assets for the 9 water and sewerage companies 2016 to 2024
| Asset type | 2016 | 2017 | 2018 | 2019 | 2020 | 2021 | 2022 | 2023 | 2024 |
|---|---|---|---|---|---|---|---|---|---|
| Foul sewer | - | 16.7 | 15.3 | 15.3 | 16.7 | 17.7 | 17.7 | 18.7 | - |
| Sewage treatment works | - | 12.3 | 13.3 | 14.3 | 14.0 | 11.7 | 12.3 | 13.7 | - |
| Rising main | - | 5.0 | 5.3 | 6.0 | 8.0 | 10.0 | 11.7 | 12.3 | - |
| Pumping station | - | 6.7 | 6.3 | 6.0 | 8.0 | 6.0 | 6.3 | 6.0 | - |
| Water distribution system (water supply) | - | 7.0 | 7.3 | 5.0 | 3.0 | 2.7 | 1.3 | 1.7 | - |
| Combined sewer overflow | - | 3.7 | 2.3 | 2.3 | 2.0 | 1.3 | 1.0 | 1.3 | - |
| Water treatment works (water supply) | - | 1.7 | 1.3 | 0.7 | 0.3 | 0.0 | 0.0 | 0.7 | - |
| Surface water outfall | - | 1.3 | 1.7 | 1.0 | 0.7 | 0.3 | 0.3 | 0.3 | - |
| Storm tank | - | 0.7 | 0.3 | 0.0 | 0.0 | 0.3 | 0.3 | 0.7 | - |
| Other water industry premises | - | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | - |
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. Pollution incident performance (category 1 to 3)
In recent years the total number of pollution incidents from sewerage and water supply assets has been increasing. The 29% increase between 2023 and 2024 is unacceptable. This is a third consecutive annual increase. The sector is failing to meet our WISER performance expectation with a 47% increase from 2016.
5.1 Performance facts for 2016 to 2024
For all pollution incidents in 2024:
- the sector total was 2,801 – this is a significant increase (29%) from 2,174 in 2023
- 8 companies deteriorated with a higher number when compared to 2023 – only South West Water had fewer incidents than 2023 but their numbers remain far too high
- for 8 companies (all except Yorkshire Water) numbers were statistically significant – this means they were higher than their average for the period
- Thames Water had the most (523) followed by Anglian Water (482), United Utilities (376), Southern Water (332), Severn Trent Water (300) and Wessex Water (248)
- Northumbrian Water (134), Yorkshire Water (197) and South West Water (209) had the lowest numbers
- due to variation in company size we normalise the number of sewerage pollution incidents per 10,000km of sewer length for which a water company is responsible – South West Water had the highest (with 108 per 10,000km sewer) and Yorkshire Water and Severn Trent Water had the lowest (both 29 per 10,000km sewer)
- the vast majority (88%) were from sewerage assets – most were from foul sewers (865) followed by PS (693), STW (647) and rising mains (176)
- there were 332 from water supply assets, an increase (22%) from 272 in 2023 – most were from the water distribution system (307)
For all pollution incidents in the period 2016 to 2024:
- sectors numbers have been unacceptably high throughout but the total in 2024 was the highest – 47% higher than 2016 (from 1,902 in 2016 to 2,801 in 2024)
- numbers have not declined which is contrary to the WISER expectation to reduce incidents by 40%
- 7 water companies deteriorated when comparing 2016 with 2024 – Anglian Water by 104%, Northumbrian Water by 21%, Thames Water by 43%, United Utilities by 96% and Wessex Water by 158% (all with an increasing trend in the most recent years) and Southern Water by 127% and South West Water by 12% (both with variable trends throughout the period)
- Yorkshire Water improved by 25% and Severn Trent Water by 2% when comparing 2016 with 2024 – but their trend has been variable, and numbers have increased in the most recent years
- South West Water had the most sewerage pollution incidents per 10,000km of sewer length for 6 of the 9 years – Southern Water had the most for the other 3 years
- the majority were from 4 asset types, all of which were worse in 2024 than 2016 – foul sewers (811 to 865), PS (361 to 693), STW (262 to 647) and water distribution system (112 to 307)
5.2 Performance data for 2016 to 2024
5.2.1 Annual number of pollution incidents (category 1 to 3) from sewerage and water supply assets, and trend for the 9 water and sewerage companies 2016 to 2024
Chart note: a statistical assessment (using the Pearson correlation coefficient) has been applied to annual data – this identifies the year 2024 to be significantly higher than the average for the data period 2016 to 2024.
5.2.2 Annual number of pollution incidents (category 1 to 3) from sewerage and water supply assets for each of the 9 water and sewerage companies 2016 to 2024
You may need to scroll horizontally to see the full table.
| Water company | 2016 | 2017 | 2018 | 2019 | 2020 | 2021 | 2022 | 2023 | 2024 |
|---|---|---|---|---|---|---|---|---|---|
| Anglian Water | 236 | 255 | 216 | 294 | 232 | 280 | 312 | 338 | 482 |
| Northumbrian Water | 111 | 59 | 61 | 66 | 62 | 91 | 81 | 112 | 134 |
| Severn Trent Water | 307 | 329 | 330 | 293 | 232 | 249 | 259 | 278 | 300 |
| Southern Water | 146 | 135 | 188 | 458 | 411 | 393 | 393 | 251 | 332 |
| South West Water | 186 | 182 | 173 | 186 | 235 | 159 | 136 | 223 | 209 |
| Thames Water | 366 | 323 | 335 | 373 | 331 | 304 | 397 | 393 | 523 |
| United Utilities | 192 | 185 | 194 | 216 | 145 | 145 | 157 | 243 | 376 |
| Wessex Water | 96 | 102 | 105 | 110 | 120 | 101 | 146 | 162 | 248 |
| Yorkshire Water | 262 | 257 | 261 | 208 | 151 | 161 | 145 | 174 | 197 |
| Sector total | 1,902 | 1,827 | 1,863 | 2,204 | 1,919 | 1,883 | 2,026 | 2,174 | 2,801 |
| Sector trend (3 year moving average) | - | 1,864 | 1,965 | 1,995 | 2,002 | 1,943 | 2,028 | 2,334 | - |
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.
5.2.3 Annual number of pollution incidents (category 1 to 3) from sewerage and water supply assets for each of the 9 water and sewerage companies 2016 to 2024, with range and average (mean)
5.2.4 Lowest, highest and average (mean) annual number of pollution incidents (category 1 to 3) from sewerage and water supply assets for each of the 9 water and sewerage companies 2016 to 2024
| Water company | Lowest in range | Highest in range | Average (mean) |
|---|---|---|---|
| Anglian Water | 216 | 482 | 293.9 |
| Northumbrian Water | 59 | 134 | 86.3 |
| Severn Trent Water | 232 | 330 | 286.3 |
| Southern Water | 135 | 458 | 300.8 |
| South West Water | 136 | 235 | 187.7 |
| Thames Water | 304 | 523 | 371.7 |
| United Utilities | 145 | 376 | 205.9 |
| Wessex Water | 96 | 248 | 132.2 |
| Yorkshire Water | 145 | 262 | 201.8 |
| Sector total | 1,468 | 3,050 | 2,066.8 |
5.2.5 Annual number of pollution incidents (category 1 to 3) from sewerage and water supply assets for each of the 9 water and sewerage companies 2016 to 2024
Chart note: annual numbers and 3 year moving averages are provided for each water company in the supporting data annex for pollution incidents.
5.2.6 Annual number of pollution incidents (category 1 to 3) from sewerage assets normalised per 10,000km sewer for each of the 9 water and sewerage companies 2016 to 2024 and trend
5.2.7 Annual number of pollution incidents (category 1 to 3) from sewerage assets normalised per 10,000km sewer for each of the 9 water and sewerage companies 2016 to 2024
| Water company | 2016 | 2017 | 2018 | 2019 | 2020 | 2021 | 2022 | 2023 | 2024 |
|---|---|---|---|---|---|---|---|---|---|
| Anglian Water | 32 | 30 | 25 | 35 | 28 | 34 | 33 | 40 | 57 |
| Northumbrian Water | 38 | 17 | 12 | 15 | 14 | 23 | 20 | 33 | 39 |
| Severn Trent Water | 30 | 30 | 31 | 26 | 21 | 22 | 21 | 26 | 29 |
| Southern Water | 35 | 31 | 39 | 110 | 102 | 94 | 90 | 59 | 68 |
| South West Water | 115 | 109 | 98 | 105 | 131 | 87 | 62 | 111 | 108 |
| Thames Water | 33 | 28 | 27 | 30 | 27 | 25 | 30 | 32 | 43 |
| United Utilities | 22 | 23 | 24 | 28 | 19 | 18 | 16 | 28 | 45 |
| Wessex Water | 22 | 23 | 24 | 22 | 25 | 21 | 31 | 36 | 62 |
| Yorkshire Water | 46 | 43 | 44 | 35 | 24 | 27 | 22 | 26 | 29 |
| Sector total | 34 | 31 | 31 | 37 | 33 | 32 | 31 | 36 | 47 |
5.2.8 The 3 year moving averages for annual number of pollution incidents (category 1 to 3) from sewerage assets normalised per 10,000km sewer for each of the 9 water and sewerage companies 2016 to 2024
| Water company | 2016 | 2017 | 2018 | 2019 | 2020 | 2021 | 2022 | 2023 | 2024 |
|---|---|---|---|---|---|---|---|---|---|
| Anglian Water | - | 28.9 | 30.1 | 30.1 | 31.3 | 30.7 | 31.6 | 35.8 | - |
| Northumbrian Water | - | 22.3 | 14.9 | 14.1 | 17.6 | 19.1 | 25.3 | 30.7 | - |
| Severn Trent Water | - | 30.3 | 29.2 | 26.0 | 22.9 | 21.0 | 22.7 | 25.1 | - |
| Southern Water | - | 35.0 | 60.0 | 83.5 | 101.9 | 95.3 | 80.9 | 72.3 | - |
| South West Water | - | 107.0 | 103.6 | 111.1 | 107.4 | 93.1 | 86.6 | 93.7 | - |
| Thames Water | - | 29.1 | 28.2 | 27.8 | 27.1 | 27.3 | 29.1 | 35.2 | - |
| United Utilities | - | 23.1 | 24.9 | 23.7 | 21.5 | 17.8 | 20.6 | 29.7 | - |
| Wessex Water | - | 23.1 | 23.0 | 23.6 | 22.6 | 25.8 | 29.4 | 43.2 | - |
| Yorkshire Water | - | 44.4 | 40.7 | 34.3 | 28.7 | 24.6 | 25.3 | 25.9 | - |
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.
5.2.9 Water and sewerage company sewer lengths
| Water company | Total length of sewers and rising mains (km) for the financial year ending 2018 |
|---|---|
| Anglian Water | 76,437 |
| Northumbrian Water | 30,026 |
| Severn Trent Water | 93,525 |
| Southern Water | 39,729 |
| South West Water | 17,440 |
| Thames Water | 108,980 |
| United Utilities | 77,339 |
| Wessex Water | 34,944 |
| Yorkshire Water | 52,263 |
Table note: this data has been used to calculate normalised pollution incidents per 10,000km of sewer. Total length is combined total of legacy sewer and those private sewers transferred in October 2011. This figure is made up of foul sewers, surface water sewers, combined sewers and rising mains.
5.2.10 Annual number of pollution incidents (category 1 to 3) from sewerage and water supply assets for the 9 water and sewerage companies 2016 to 2024 and trend
Chart note: data for surface water outfalls, water treatment works (water supply), storm tanks and other water industry premises is not plotted due to low numbers compared to other asset types.
5.2.11 Annual number of pollution incidents (category 1 to 3) from sewerage and water supply assets for the 9 water and sewerage companies 2016 to 2024
| Asset type | 2016 | 2017 | 2018 | 2019 | 2020 | 2021 | 2022 | 2023 | 2024 |
|---|---|---|---|---|---|---|---|---|---|
| Foul sewer | 811 | 786 | 746 | 809 | 689 | 625 | 641 | 678 | 865 |
| Pumping station | 361 | 281 | 311 | 500 | 448 | 442 | 361 | 472 | 693 |
| Sewage treatment works | 262 | 259 | 314 | 385 | 306 | 364 | 381 | 487 | 647 |
| Water distribution system (water supply) | 112 | 177 | 215 | 231 | 190 | 189 | 345 | 250 | 307 |
| Rising main | 105 | 133 | 132 | 127 | 120 | 136 | 149 | 166 | 176 |
| Combined sewer overflow | 160 | 123 | 94 | 81 | 116 | 83 | 80 | 65 | 63 |
| Surface water outfall | 57 | 33 | 17 | 34 | 24 | 21 | 36 | 19 | 19 |
| Water treatment works (water supply) | 18 | 23 | 25 | 21 | 14 | 17 | 23 | 22 | 25 |
| Storm tank | 12 | 8 | 4 | 10 | 5 | 5 | 7 | 5 | 3 |
| Other water industry premises | 4 | 4 | 5 | 6 | 7 | 1 | 3 | 10 | 3 |
5.2.12 The 3 year moving average for annual number of pollution incidents (category 1 to 3) from sewerage and water supply assets for the 9 water and sewerage companies 2016 to 2024
You may need to scroll horizontally to see the full table.
| Asset type | 2016 | 2017 | 2018 | 2019 | 2020 | 2021 | 2022 | 2023 | 2024 |
|---|---|---|---|---|---|---|---|---|---|
| Foul sewer | - | 781.0 | 780.3 | 748.0 | 707.7 | 651.7 | 648.0 | 728.0 | - |
| Pumping station | - | 317.7 | 364.0 | 419.7 | 463.3 | 417.0 | 425.0 | 508.7 | - |
| Sewage treatment works | - | 278.3 | 319.3 | 335.0 | 351.7 | 350.3 | 410.7 | 505.0 | - |
| Water distribution system (water supply) | - | 168.0 | 207.7 | 212.0 | 203.3 | 241.3 | 261.3 | 300.7 | - |
| Rising main | - | 123.3 | 130.7 | 126.3 | 127.7 | 135.0 | 150.3 | 163.7 | - |
| Combined sewer overflow | - | 125.7 | 99.3 | 97.0 | 93.3 | 93.0 | 76.0 | 69.3 | - |
| Surface water outfall | - | 35.7 | 28.0 | 25.0 | 26.3 | 27.0 | 25.3 | 24.7 | - |
| Water treatment works (water supply) | - | 22.0 | 23.0 | 20.0 | 17.3 | 18.0 | 20.7 | 23.3 | - |
| Storm tank | - | 8.0 | 7.3 | 6.3 | 6.7 | 5.7 | 5.7 | 5.0 | - |
| Other water industry premises | - | 4.3 | 5.0 | 6.0 | 4.7 | 3.7 | 4.7 | 5.3 | - |
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. Self-reporting of pollution incidents
In recent years we have seen some water companies achieve high levels of self-reporting of pollution incidents with the best overall sector performance in 2024. The sector as a whole has responded positively to the WISER expectation improving self-reporting rates. However, some companies have issues at specific assets. We expect all water companies to consistently achieve WISER and continue to improve self-reporting rates in future years.
6.1 Performance facts for 2016 to 2024
For self-reporting in 2024:
- the sector performance for all incidents was 85% – a small improvement compared to 84% in 2023 and the best performance to date
- the best performing companies for all incidents were Wessex Water (92%) followed by Northumbrian Water, Severn Trent Water, United Utilities (all 90%)
- the 2 companies with the lowest percentage for all incidents were Thames Water (75%) and Yorkshire Water (78%)
- the sector achieved 92% for all incidents from just PS and STW combined, compared to 93% in 2023 – we expect higher self-reporting from these permitted assets as they normally have alarms or staff on site
- Severn Trent Water was the only company to achieve 100% for all incidents from just PS and STW combined
- the sector performance for serious pollution incidents was 63% (47 out of 75), a decline from 74% in 2023 (35 out of 47) – given the environmental impact of these incidents we want to see further improvement
- only 4 out of 11 (36%) category 1 incidents (the most serious) were self-reported
For self-reporting in the period 2016 to 2024:
- 2024 was the highest year ever of self-reporting for the sector – there has been a steady improvement of 13% when comparing 2016 (72%) with 2024 (85%)
- the high percentages for some companies means that the sector average has met our WISER expectation for the last 3 years (2022, 2023 and 2024)
- 3 water companies met our WISER expectation for 4 consecutive years from 2021 to 2024 (Northumbrian Water, Severn Trent Water and Wessex Water)
- across the sector, for category 1 to 3 incidents, there was an overall improvement at asset types with the highest incident numbers – however there was only small improvement for rising mains (84% in 2016 to 85% in 2024) and foul sewers (67% in 2016 to 73% in 2024)
- for PS incidents (category 1 to 3) 8 water companies improved however further progress is expected – Yorkshire Water was the only water company to deteriorate between 2016 and 2024 (from 91% to 82%)
- for STW incidents (category 1 to 3) all companies have improved showing a positive response to the WISER expectation
- for foul sewer incidents (category 1 to 3) Thames Water deteriorated between 2016 and 2024 (75% to 63%) – 2 companies made little or no improvement (South West Water 50% in 2016 and 53% in 2024 and Yorkshire Water remained 70%)
- for water distribution system incidents (category 1 to 3) most water companies have improved – however 3 water companies (United Utilities, Yorkshire Water and Wessex Water) had a slight deterioration
- across the sector for category 1 to 2 serious incidents there was an overall improvement across asset types with the highest incident numbers – however there was a disappointing decline for STW (82% in 2016 compared to 70% in 2024) and more progress is needed on foul sewers (37% in 2016 to 41% in 2024)
6.2 Performance data for 2016 to 2024
6.2.1 Percentage self-reporting of pollution incidents (category 1 to 3) from sewerage and water supply assets, and trend for the 9 water and sewerage companies 2016 to 2024
6.2.2 Annual percentage self-reporting of pollution incidents (category 1 to 3) from sewerage and water supply assets for each of the 9 water and sewerage companies 2016 to 2024
| Water company | 2016 | 2017 | 2018 | 2019 | 2020 | 2021 | 2022 | 2023 | 2024 |
|---|---|---|---|---|---|---|---|---|---|
| Anglian Water | 66 | 71 | 62 | 71 | 73 | 69 | 73 | 89 | 88 |
| Northumbrian Water | 68 | 80 | 84 | 80 | 81 | 89 | 91 | 94 | 90 |
| Severn Trent Water | 79 | 80 | 79 | 78 | 76 | 80 | 87 | 89 | 90 |
| Southern Water | 71 | 70 | 83 | 87 | 88 | 90 | 90 | 69 | 82 |
| South West Water | 64 | 68 | 77 | 76 | 74 | 68 | 78 | 82 | 82 |
| Thames Water | 67 | 73 | 76 | 78 | 63 | 65 | 74 | 76 | 75 |
| United Utilities | 75 | 82 | 79 | 90 | 82 | 81 | 88 | 94 | 90 |
| Wessex Water | 76 | 78 | 74 | 85 | 85 | 90 | 92 | 94 | 92 |
| Yorkshire Water | 79 | 83 | 73 | 73 | 81 | 66 | 77 | 75 | 78 |
| Sector total | 72 | 76 | 76 | 80 | 77 | 77 | 82 | 84 | 85 |
| Sector trend (3 year moving average) | - | 74.5 | 77.2 | 77.7 | 78.1 | 78.8 | 81.0 | 83.7 | - |
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.
6.2.3 Percentage of pollution incidents (category 1 to 3) self-reported from sewerage and water supply assets for each of the 9 water and sewerage companies 2016 to 2024 and trend
Chart note: annual numbers and 3 year moving averages are provided for each water company in the supporting data annex for self-reporting of pollution incidents.
6.2.4 Percentage of pollution incidents (category 1 to 3) self-reported from sewerage and water supply assets for the 9 water and sewerage companies in 2016 compared to 2024
| Asset type | 2016 percentage self-reporting of pollution incidents | 2024 percentage self-reporting of pollution incidents |
|---|---|---|
| Foul sewer | 67 | 73 |
| Pumping station | 81 | 93 |
| Rising main | 84 | 85 |
| Sewage treatment works | 79 | 91 |
| Water distribution system (water supply) | 81 | 90 |
Chart note: only assets with the highest number of incidents in 2024 are displayed in the chart above.
6.2.5 Percentage of serious pollution incidents (category 1 and 2) self-reported from sewerage and water supply assets for the 9 water and sewerage companies in 2016 compared to 2024
| Asset type | 2016 percentage self-reporting of serious pollution incidents | 2024 percentage self-reporting of serious pollution incidents |
|---|---|---|
| Foul sewer | 37 | 41 |
| Pumping station | 30 | 64 |
| Rising main | 75 | 87 |
| Sewage treatment works | 82 | 70 |
Chart note: only assets with the highest number of serious incidents in 2024 are displayed in the chart above.
6.2.6 Percentage of pollution incidents (category 1 to 3) self-reported from foul sewers for each of the 9 water and sewerage companies in 2016 compared to 2024
| Water company | 2016 percentage of pollution incidents self-reported from foul sewers | 2024 percentage of pollution incidents self-reported from foul sewers |
|---|---|---|
| Anglian Water | 59 | 81 |
| Northumbrian Water | 56 | 79 |
| Severn Trent Water | 73 | 81 |
| Southern Water | 55 | 69 |
| South West Water | 50 | 53 |
| Thames Water | 75 | 63 |
| United Utilities | 65 | 80 |
| Wessex Water | 68 | 84 |
| Yorkshire Water | 70 | 70 |
6.2.7 Percentage of pollution incidents (category 1 to 3) self-reported from pumping stations for each of the 9 water and sewerage companies in 2016 compared to 2024
| Water company | 2016 percentage of pollution incidents self-reported from pumping stations | 2024 percentage of pollution incidents self-reported from pumping stations |
|---|---|---|
| Anglian Water | 71 | 97 |
| Northumbrian Water | 91 | 96 |
| Severn Trent Water | 87 | 100 |
| Southern Water | 85 | 88 |
| South West Water | 81 | 90 |
| Thames Water | 61 | 75 |
| United Utilities | 91 | 95 |
| Wessex Water | 85 | 98 |
| Yorkshire Water | 91 | 82 |
6.2.8 Percentage of pollution incidents (category 1 to 3) self-reported from the water distribution system for each of the 9 water and sewerage companies in 2016 compared to 2024
Chart note: Northumbrian Water not plotted as no incidents from the water distribution system in 2016.
| Water company | 2016 percentage of pollution incidents self-reported from the water distribution system | 2024 percentage of pollution incidents self-reported from the water distribution system |
|---|---|---|
| Anglian Water | 50 | 95 |
| Northumbrian Water | not applicable | 88 |
| Severn Trent Water | 83 | 96 |
| Southern Water | 71 | 95 |
| South West Water | 75 | 84 |
| Thames Water | 33 | 86 |
| United Utilities | 93 | 88 |
| Wessex Water | 95 | 90 |
| Yorkshire Water | 95 | 80 |
7. Pollution interventions
As the environmental regulator, it’s our role to ensure water companies comply with the law and protect the environment. It is their responsibility to meet the conditions we set in their licences and permits and meet their statutory obligations.
But water industry performance is still not where it needs to be and that is why we’ve made significant changes to the way we regulate. Through a modernised and expanded regulatory approach, we are increasing our scrutiny, getting ahead of the issues and bringing our evidence to bare. Last year we exceeded our ambitious target of 4,000 inspections of regulated sites and this year we are on track to deliver 10,000.
With over 400 new roles focused on water industry regulation, greater capabilities through enhanced digital tools and analysis, we are taking a more proactive and preventative approach to target our work. This shift ensures that we don’t just focus on compliance and maintenance but also on long-term planning, investment, and tackling root causes.
Building on our transformation are the new powers we will receive through the Water (Special Measures) Act (WSMA). This will lead to significant changes in how we regulate the water industry, enabling faster, firmer action against poor performance. It will speed up civil penalties for less serious offences, so that we can focus prosecutions on the most serious offending. We welcome this opportunity to step up our regulation and the government’s ambition to drive through much needed reform.
7.1 Planning and investment
While increased inspections will lead to appropriate and proportionate enforcement action, alone they won’t achieve the step change we want to see in water industry performance.
Where appropriate, intelligence gathered from inspections can be used by water companies to plan how they will reduce pollution incidents and extend, improve and maintain a resilient drainage and wastewater system. They will do this through pollution incident reduction plans (PIRPs) and drainage and wastewater management plans (DWMPs).
Pollution incident reduction plans (PIRPs)
The WSMA has introduced a new statutory requirement. Water companies must produce and publish annual PIRPs (starting April 2026) with an accompanying implementation report (starting April 2027) to demonstrate progress. These publicly available plans are expected to further increase transparency regarding water company actions to reduce the severity and frequency of pollution incidents. This will enable regulators, the public and customers to better hold water companies accountable. We will publish statutory guidance that companies will have to follow when drawing up these plans. This is expected to resolve issues with the consistency and level of ambition of existing non-statutory PIRPs across companies, enabling greater regulatory oversight.
Recently, water companies have reported the most effective measures to be basic proactive cleaning and maintenance programmes and use of telemetry data to pre-empt pollution incidents. Water companies must go further to identify the true underlying root causes of pollution incidents and ensure that corresponding measures are delivered at a scale that meets the asset health need. We will continue to track and monitor company delivery of PIRPs.
PIRPs complement the more strategic drainage and wastewater management plans, providing a framework for the planning of short-term, tactical incident response within the longer-term strategic approach.
Drainage and wastewater management plans (DWMPs)
Drainage and wastewater management plans are statutory water industry plans. They are vital to set out actions to extend, improve and maintain a robust and resilient drainage and wastewater system that faces pressures from climate change, urban development and a growing population.
Environmental and pollution incidents may not always be under the direct control of a water company, for example those linked to the effects of climate change such as severe storms. But water companies must strive to protect their assets and look to work with others to do this. DWMPs identify short, medium and long-term investment needs for wastewater and drainage. They ensure water companies:
- prepare for climate change and deliver catchment resilience and capacity, ahead of need
- proactively maintain and improve asset health and performance
- manage surface water at source, working collaboratively with others
DWMPs will provide the evidence base for all water companies’ drainage and wastewater investment needs over the next 25 years. This includes investment needed to reduce both total and serious pollution incidents. Plans are due to be published in draft by November 2027, for a 12 week public consultation, and final plans by August 2028, ahead of the price review (PR29). We expect companies to be transparent on the scale and pace of investment need, particularly associated with the challenges associated with aging infrastructure.
For more information see our guidelines for statutory Drainage and Wastewater Management Plans (DWMPs).
Water company investment 2025 to 2030 (PR24)
Ofwat’s 2024 price review (PR24) final determination has set base expenditure allowances of £20 billion for the wastewater network that companies are expected to use to provide a base level of good service to customers and to maintain the long-term capability of assets over the 2025 to 2030 period.
Water companies are expected to use the increased expenditure to maintain and improve the health of their asset base, taking into account the impact of climate change in the 2025 to 2030 period.
The PR24 final determination has also set asset health performance commitments to incentivise companies to appropriately maintain and improve the asset health of their infrastructure, reducing adverse environmental impacts such as spills from storm overflows in the long term.
7.2 Monitoring and data
Data
We now have access to vast amounts of data from nearly 15,000 Event Duration Monitors (EDM) at storm overflows. We have developed processes and tools to map this data intelligently and allow us to direct our regulatory resource to those places that need it the most.
We also have access to data from flow monitors at STW and will soon have access to data from continuous water quality monitors.
The new WSMA will bring in further duties for water companies to monitor emergency overflows and publish data within an hour of a discharge for all emergency overflows in England.
Environment Agency guidance
We recently held a targeted consultation on the way in which we record water company pollution incidents. We plan to make changes to improve transparency and consistency and are already including new data from monitoring of storm overflows (EDM). This identifies when storm overflows spill on a dry day which were previously undetected. We will now class these as pollution incidents from 2026 data and highlight these to the public.
Digital systems and intelligence
New monitoring, digital systems and tools are improving and will streamline how we monitor the water industry, check compliance, track corrective actions, and support enforcement.
By making data more accessible and connected, we can develop intelligence-led solutions such as our Risk Planning Tool. This brings together the wider picture, supports the creation of intelligence and helps prioritise resources where they will have the greatest impact.
7.3 Environment Agency resource
Incident response
We respond to all pollution incidents. We will continue to attend all category 1 and 2 (serious and significant) water industry incidents and we will be increasing our attendance at category 3 (minor) incidents. This will enable us to gain intelligence on the root cause of these incidents, record the impact, and take appropriate and proportionate action in line with our enforcement and sanctions policy.
Inspections
With an increased workforce, specialist training and advanced digital technology we have been carrying out more inspections of regulated sites. Earlier this year we exceeded our target of 4,000 inspections ahead of the deadline of 31 March 2025. This year we are on track to deliver 10,000 inspections. More inspections will identify more issues but over time this will provide vital evidence so that companies can improve compliance and act early to prevent incidents.
We record the findings of our inspections on water discharge compliance assessment report (CAR) forms which are now published on the public register. This supports our ambition to be a more open and transparent regulator and meets the aims of the Environmental Information Regulations. All breaches are acted upon, and while companies have shown they can act quickly on our advice we’re also uncovering longer-term issues linked to deteriorating assets which take longer to investigate and put right.
7.4 Engagement
Regulator engagement
We continue to work closely with other regulators sharing data and intelligence on water company performance.
We have been working with Ofwat on greater alignment of financial penalties and environmental performance. This includes sharing our incident data with Ofwat to inform their assessment of common performance commitments and the implementation of the new rule prohibiting water company executives’ performance related pay.
Water company engagement
We continue to engage with water companies at chair, executive director and operational levels throughout the year. We expect water companies to work together and share good practice and innovative approaches to reduce pollution incidents.
7.5 Future requirements
Water industry strategic environmental requirements for 2025 to 2030
We have published our WISER performance expectations for 2025 to 2030. This sets out the expected approaches water companies should follow during PR24 and beyond. We expect the sector to achieve zero serious pollution incidents, significantly reduce all pollution incidents, and we set a higher expectation on self-reporting of pollution incidents.
Future performance reporting
We recently held a targeted consultation on how we should report on the performance of water companies in the future (2026 to 2030 data years).
7.6 Enforcement and sanctions
Between 2016 and May 2025 there have been 57 prosecutions of water companies (some involving multiple cases) – 55 of those resulted from pollution incidents or permit breaches affecting water quality, securing fines of over £149 million. In 2024:
- we completed 6 prosecutions against 4 different water companies – 5 of the prosecutions resulted from pollution incidents or permit breaches affecting water quality which led to total fines of £3,502,000
- we accepted 10 enforcement undertaking offers from 3 different water companies – 9 of the enforcement undertakings resulted from pollution incidents or permit breaches affecting water quality totalling £3,193,780
Enforcement and sanctions resulting from pollution incidents or permit breaches affecting water quality for the 9 water and sewerage companies 2016 to 2024
| Year | Number of prosecutions | Value of prosecution fines | Number of enforcement undertakings | Value of enforcement undertakings |
|---|---|---|---|---|
| 2016 | 10 | £6,560,000 | 4 | £595,000 |
| 2017 | 9 | £21,589,334 | 15 | £595,000 |
| 2018 | 3 | £427,000 | 15 | £1,435,900 |
| 2019 | 5 | £3,097,000 | 10 | £3,432,150 |
| 2020 | 3 | £852,000 | 14 | £2,404,760 |
| 2021 | 7 | £102,490,000 | 9 | £2,465,901 |
| 2022 | 9 | £4,198,750 | 3 | £1,703,272 |
| 2023 | 3 | £5,994,000 | 5 | £500,000 |
| 2024 | 5 | £3,502,000 | 9 | £3,193,780 |
| 2025 (to 31 May) | 1 | £350,000 | 5 | £2,297,424 |
| Total | 55 | £149,060,084 | 89 | £18,623,187 |
Table note: cases against a water company sentenced in court on the same day count as one prosecution. If a prosecution has an appeal hearing it is recorded here according to the date of the final hearing not the original prosecution.
Before taking enforcement action, we must investigate to gather evidence, consider the facts and establish matters relevant to public interest and sentencing. This takes time and our enforcement activity can conclude some months or years after the original offence occurred, particularly court cases.
Prosecution continues to be an important response where it is in the public interest, as a proportionate and outcome focused enforcement option to protect the environment. Prosecution is rightly reserved for those pollution incidents and permit or licence breaches where there is serious, actual or potential environmental harm and a high level of culpability. Fines continue to reflect the size of the organisation concerned as well as the offence category. Sentencing is a matter for the courts who fine on a case-by-case basis, and for this reason fines vary significantly.
An enforcement undertaking is a voluntary agreement offered by those who have committed a less serious offence that becomes legally binding once accepted. It funds local environmental improvements but also requires that steps are taken to put right what went wrong and to prevent it happening again.
The WSMA will enable us to speed up our enforcement response by imposing faster and more predictable civil penalties for the less serious level of offending. It will also enable us to focus our prosecution activities on the most serious offences and allow us to recover enforcement costs from water companies. For obstruction offences strengthening penalties to prevent water companies blocking investigations and to make sure they face the consequences of their actions and inaction.
When a water company fails to comply with the conditions of its environmental permit the most serious breaches can trigger a formal investigation. We expect full compliance with environmental permits to prevent pollution incidents and protect the environment. With the increase in inspections, we have uncovered more non-compliances. This includes 81 serious breaches identified between July 2024 and March 2025 which we are investigating.
We are continuing with our major investigation of all the water companies into potential wastewater treatment works flow-to-full treatment (FFT) non-compliance.
8. Conclusions
The water industry is fundamental to the future health of people, wildlife, growth and the economy. That’s why it’s critical that water companies deliver on their commitments.
This report gives an insight into the unacceptable and continuing high level of pollution incidents caused by water companies. We are committed to transparency and enabling scrutiny of the data we hold so everyone can see what is going on. Only by highlighting the true scale of the problem can we ensure that water companies are taking the right actions to tackle the root cause of issues both in the short and long term. Looking back over the period 2016 to 2024 incident numbers have been consistently too high and remain a huge environmental and reputational issue for the sector. We set realistic expectations however the sector has not met them.
Serious incident numbers have increased, although we give credit to the few individual companies that show a target of zero can be met. We acknowledge the new rule under the Water (Special Measures) Act (WSMA) – prohibiting water company executives’ performance related pay where a company has caused an incident with a major impact to the water environment (category 1).
The recent upturn in all pollution incidents and failure to meet our expectations is hugely disappointing and we expect to see rapid action to change this trajectory. The causes for a high number of incidents can be complex and often company specific. Each company must demonstrate an immediate and proactive approach to prevent pollution incidents rather than fix on fail. The new WSMA statutory requirement for water company PIRPs will ensure company plans become more focused and effective to deliver more immediate results. There is no excuse for companies to not act immediately on problems that can be fixed in a short timescale.
We recognise that infrastructure development requires longer-term investment. The data and intelligence we are collecting with more staff, new monitoring tools and our improved digital capability is highlighting persistent problems across the sector. These are due to poor asset health, underinvestment in maintenance and replacement of aging infrastructure as well as reduced resilience due to the impacts of climate change.
We welcome the improvement in self-reporting of pollution incidents and that the sector has met expectations for this. However, we need to see even higher levels of self-reporting as we move to new expectations set to further protect the environment by 2030.
We will continue, with government and other regulators, to drive positive interventions by the water companies to protect the water environment. We won’t hesitate to take action if their performance does not improve.