Our Research Into Water Pollution Incidents In The UK

Serious water pollution incidents in the UK

Water pollution has become a major issue for many people in the UK. With scores of incidents and anecdotal evidence mounting, we set out to uncover the true extent of the problem.

Below, you can find exclusive statistics we’ve compiled as a result of our research into water pollution incidents in the UK.

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How Did We Conduct Our Research Into Water Pollution Incidents?

We sent a Freedom of Information Request to the Environment Agency asking for the number of serious pollution incidents each water company in the UK has had in the last five years. By pollution incidents, we refer to the number of times pollution has been caused by spilling or discharging sewage into waterways in breach of environmental rules.

We also asked for the causes of such incidents as well as the contributing pollutant.

The Environment Agency provided the number of serious pollution incidents from the following water companies, broken down by financial year:

• Anglican Water
• Northumbrian Water
• Severn Trent Water
• Southern Water
• South West Water
• Thames Water
• United Utilities
• Welsh Water
• Wessex Water
• Yorkshire Water

However, results for Northumbrian Water and United Utilities were incomplete. The Environment Agency has been contacted for comment.

As such, we have collated results and omitted any from Northumbrian Water and United Utilities.

The Results

National

Serious Water Pollution Incidents (2024) by Water Company

Figures obtained from the Environmental Agency reveal the majority of England’s nine water and sewage companies have recorded 92% of ‘serious pollution incidents’ this year alone. 

It comes as firms face £168m in fines from industry regulator Ofwat for historic sewage spills. 

The data we obtained shows the top water companies with the most reported serious pollution incidents in the last five years. 

It also reveals the leading causes and pollutants in England and Wales since 2019.

The Environment Agency categorises water pollution incidents as serious if they fall into their two highest categories: major (category 1) or significant (category 2).

Serious incidents can include events that, for example, cause fish to die, potentially harm bathers or force a drinking water provider to temporarily stop abstracting water from a river

Thames Water recorded the most serious water pollution incidents this year with a total of 20, an increase of 25% from 2023.

However, Yorkshire Water reported the highest increase in a 12- month period. The number of serious incidents skyrocketed by 83% from 6 incidents last year, to 11 in 2024 so far. 

A further 8 incidents were logged by Southern Water, down from 16 the year before and Anglian Water had 6 incidents down from 11 in 2023. 

Figures for serious water pollution incidents for Severn Trent and Northumbrian Water are missing data for 2024. The Environment Agency has been contacted for comment on this. 

It comes as Thames Water, Yorkshire Water and Northumbrian Water face £168m fines by Ofwat over historic sewage spills. 

The industry regulator made the announcement on Wednesday (July, 31) amidst growing public fury over the environmental and financial performance of some water companies. 

The proposal will go to public consultation and is part of Ofwat’s largest ever investigation into water company performance. 

Thames Water are facing fines of £104m from the industry regulator. Ofwat can fine companies up to 10% of their annual sales. In this case, the proposed fine is 9% of sales.

The data obtained by Legal Expert also shows the leading causes and pollutants contributing to ‘serious water pollution incidents’ in England and Wales over the past five years. 

Between 2019-2024, ‘Containment and Control’ was the leading cause, accounting for 83% of all reported ‘serious incidents’ in the last five years. 

This could include pipeline failures meaning hazardous materials transported through pipelines are released into the environment. Some 250 incidents have been recorded since 2019. 

In 79% of these cases, crude sewage was the pollutant – which is raw sewage that has not been treated.

The second most common cause of serious water pollution incidents was ‘Sewer Failure or Overflow.’ Some 113 incidents have been recorded since 2019, accounting for 37%.

A further 47 serious incidents have been caused by ‘pipe failure below ground’ and ‘;control measure failure’ was to blame for 22 incidents. 

Leading Causes of Serious Water Pollution Incidents

Thames Water Utilities Ltd

Serious Water Pollution Incidents – Thames Water 2019-2024

Thames Water has recorded a 25% rise in serious water pollutant incidents this year, new figures reveal.

It reported the highest number of serious water pollution incidents out of all nine water companies in the UK.

The country’s largest household supplier reported 16 category one (the most serious) pollution incidents in 2023, rising to 20 in 2024. 

Thames Water is facing fines of £104m from industry regulator, Ofwat over historic sewage spills. 

Ofwat can fine companies up to 10% of their annual sales. In this case, the proposed fine is 9% of sales.

‘Serious Pollution Incidents’ Recorded by Thames Water In The Last Five Years

2019 | 14

2020 | 13

2021 | 11

2022 | 20

2023 | 16

2024 | 20

Total | 94

Anglian Water Services Limited

‘Serious Pollution Incidents’ Recorded by Anglican Water In The Last Five Years

2019 | 12

2020 | 12

2021 | 14

2022 | 11

2023 | 11

2024 | 6

Total | 36

Southern Water Services Ltd

Serious Water Pollution Incidents – Southern Water 2019-2024

‘Serious Pollution Incidents’ Recorded by Southern Water In The Last Five Years

2019 | 6

2020 | 4

2021 | 11

2022 | 6

2023 | 16

2024 | 8

Total | 51

Yorkshire Water Services Ltd

Serious Water Pollution Incidents – Yorkshire Water

‘Serious Pollution Incidents’ Recorded by Yorkshire Water In The Last Five Years

2019 | 9

2020 | 3

2021 | 5

2022 | 2

2023 | 6

2024 | 11

Total | 36

Wessex Water Plc

‘Serious Pollution Incidents’ Recorded by Wessex Water In The Last Five Years

2019 | 1

2020 | 4

2021 | 5

2022 | 5

2023 | 1

2024 | 2

Total | 18

South West Water (SWW)

‘Serious Pollution Incidents’ Recorded by South West Water In The Last Five Years

2019 | 1

2020 | 3

2021 | 8

2022 | 3

2023 | 2

2024 | 1

Total | 18

Severn Trent Water Ltd

‘Serious Pollution Incidents’ Recorded by Severn Trent Water In The Last Five Years

2019 | 5

2020 | 1

2021 | 3

2022 | 1

2023 | 1

2024 | N/A

Total | 11*

Northumbrian Water

‘Serious Pollution Incidents’ Recorded by Northumbrian Water In The Last Five Years

2019 | 2

2020 | 1

2021 | 2

2022 | N/A

2023 | 1

2024 | N/A

Total | 6*

United Utilities Water Plc

‘Serious Pollution Incidents’ Recorded by United Utilities Water In The Last Five Years

2019 | N/A

2020 | N/A

2021 | 1

2022 | N/A

2023 | 1

2024 | 1

Total | 3*