2023 Sewage Figures

Deep Dive

Spills

this decade

In 2023, there were a total of 464,056 sewage discharges into English rivers, waterways, and seas, averaging 1,271 sewage spills per day. This amounted to a staggering 3.6 million hours (about 410 and a half years) of sewage spills into English waterways over the course of the year.

When we include EDM data from Wales, Scotland and Northern Ireland, there was a total of 584,001 spills in 2023. This is a 42% increase from 411,927 sewage spills in 2020. Forecasting shows that if these trends were to continue with impunity, then by 2035 there would be over 1 million sewage spills per year.

This report will demonstrate that the UK sewage scandal is likely far more extensive than currently estimated, with varying impacts across different areas and will only get worse if governments continue not to act. By conducting a deep dive into the data on sewers, bathing waters, and rivers, as well as examining differences in other devolved nations of the UK and constituencies, this report will reveal the sheer number and hours of sewage that was spilled last year.

2020

2021

2022

2023

Total

Yorkshire Water

65,083

70,062

54,273

77,761

267,179

Wessex Water

28,994

23,524

21,878

41,453

115,849

Welsh Water

88,528

74,006

108,860

271,394

United Utilities

113,940

81,588

69,245

97,537

362,310

Thames Water

18,443

14,713

8,014

16,990

58,160

Southern Water

19,782

19,077

16,688

29,494

85,041

South West Water

42,053

42,484

37,649

58,249

180,435

Severn Trent Water

60,982

59,684

44,765

60,253

225,684

Scottish Water

12,725

10,715

14,052

15,289

52,781

Northumbrian Water

32,497

36,483

29,697

46,492

145,169

Anglian Water

17,428

21,351

16,082

31,623

86,484

EDMs EXplained

Before diving deep into the sewage data, let’s take a minute to reflect on what EDM systems are and why the data is useful.

Event Duration Monitoring (EDM) is a method used to measure and record the duration and frequency of sewage overflows, and are installed on permitted assets discharging to Water Framework Directive water bodies, which are:

1. Combined sewer overflows (CSOs) on the sewer network including pumping stations
2. Storm overflows at the inlet to sewage treatment works (STWs)
3. Storm discharges from storm tanks at STWs

The EDM system uses sensors and data loggers installed at overflow points. These devices detect and record the start and end times of overflow events, capturing the duration and frequency of discharges. Each water company has a discharge permit, which allows a certain amount of sewage to be discharged, monitoring and reporting requirements form part of this permit.

The data collected through EDM helps regulatory bodies, environment agencies, and water companies understand the patterns and impact of sewage overflows. This information is crucial for improving wastewater management practices, upgrading infrastructure, and ensuring compliance with environmental regulations. In the context of the UK sewage scandal, EDM data has become critical in illustrating the scale and frequency of sewage discharges. However, this data is not without its challenges and limitations. Currently, this data is focused on the hours and number of spills, not the volume of sewage entering our waterways. This means that the actual amount of sewage entering bodies of water is unknown and therefore makes this data somewhat unreliable. The limitations of EDM as a method for calculating the amount of sewage going into our waterways will be examined later in this report.

Average spills

per asset between 2021 and 2023

South West Water and United Utilities have consecutively poor performance when looking at average spills per assets between 2021 and 2023. Since 2021, South West Water has seen a 14% increase in the average spills per asset. 2022 overall seemed a slightly better year for water companies’ average number of spills per asset, with a decrease in average spills per asset across the board. However, 2023 saw all water companies’ average spill per asset increase, with Wessex Water seeing a 69% increase between their average spills per asset in 2022 and 2023. However, while Wessex Water saw the biggest increase by way of percentage difference, the worst performing was South West Water with an average spill per asset of 52.1.

Water Company

2021

%

2022

%2

2023

Anglian Water

29

39

17.5

54

27.02

Dwr Cymru

33.65

18

27.72

36

37.8

Northumbrian Water

28.93

18

23.66

42

33.64

Severn Trent

30.12

24

22.97

27

29.09

South West Water

45.9

19

37.22

40

52.1

Southern Water

24.8

11

22.1

63

36.1

Thames Water

35.03

40

21.2

62

34.3

United Utilities

46.7

11

41.46

21

50.1

Wessex Water

25.48

14

22

69

37.07

Yorkshire Water

38.92

21

30.78

35

41.7

The table shows the average spills per asset per water company between 2021 and 2023 and the percentage difference.

Based on this data, the water companies are ranked from worst to best as follows:

  1. Anglian Water
  2. Northumbrian Water
  3. Thames Water
  4. Southern Water
  5. Wessex Water
  6. Dwr Cymru
  7. Yorkshire Water
  8. United Utilities
  9. South West Water

 

There was a 63% difference between the worst and best performing water companies in 2023, with South West Water crowned as the worst and Anglian Water as the best for average spills per asset.

Spill forecasting

Based on average spills per asset

Based on the data above, future spill forecasting of what average spills per asset might look like in 2030 and 2035 was completed. This data shows that if present levels of spills continue, there will be an exponential increase for some water companies, while others will improve. This will then create a wider disparity and difference in the spills by the water companies.

Within this, Southern Water, South West Water and Wessex Water will continue to be the worst performing water companies, with Anglian Water being the cleanest by some fair stretch.

Water Company

2030

2035

Anglian Water

16.5

11.6

Dwr Cymru

49.65

60

Northumbrian Water

47.49

59.22

Severn Trent

23.27

20.69

South West Water

69.87

85.37

Southern Water

72.86

101.11

Thames Water

27.25

25.43

United Utilities

59.68

68.18

Wessex Water

74.53

103.51

Yorkshire Water

48.25

55.2

Sewers

From the data, it can be seen that 60% of sewage discharges come from the sewer network itself, with 20% from discharge at the sewer pump, 14% from storm tanks at wastewater and treatment works sites.

Turning to look at sewage treatment work sites more specifically, the table below shows the 5 worst sewage treatment works for number of spills. This table also shows the duration of spills and the operational site percentage. This data shows that Severn Trent Water had 4 of the top 5 worst performing sewage treatment works, with a total number of spills in the top 5 from their sites of 755. Furthermore, the Church Stretton Sewage works is listed as one of the worst performing, yet it only had an operational percentage of 68.5%, meaning that there was 31.5% of the year when this site was not operational.

Sewage Treatment Works

Water Company

No. of spills

Duration of spills

Operational %

Shrewton Water Recycling Centre

Wessex Water

262

6183.92

99.78

Kimcote Sewage Treatment Works

Severn Trent Water

205

2364.34

100

Northend Sewage Treatment Works

Severn Trent Water

196

243.81

85.6

Church Stretton Sewage Treatment Works

Severn Trent Water

177

3852.1

68.5

Gaulby Sewage Treatment Works

Severn Trent Water

177

2669.3

99.7

Bathing Waters

The table below shows the top 20 most polluted bathing waters in 2023. United Utilities had the most spills into their bathing waters, with 13 of the top 20 being within their catchment area. Meanwhile, South West Water has 3 in the top 20 polluted bathing waters, with Yorkshire Water, Thames Water, Northumbrian Water, and Southern Water making up the remainder of the top 20.

Rank

Bathing Water

Water Company

Spills

1

New Brighton

United Utilities

1,485

2

St Annes

United Utilities

1,290

3

Plymouth Hoe (East)

South West Water

1,264

4

Allonby

United Utilities

871

5

Fleetwood

United Utilities

781

6

Wharfe at Cromwheel, Ilkley

Yorkshire Water

742

7

Wolvercote Mill Stream

Thames Water

729

8

Spittal

Northumbrian Water

680

9

Cowes, Gurnard

Southern Water

649

10

Wallasey

United Utilities

613

11

Walney Biggar Bank; Walney West Shore; Walney Sandy Gap

United Utilities

514

12

Seascale

United Utilities

466

13

Mothecombe Beach

South West Water

465

14

East Looe Beach

South West Water

451

15

Walney West Shore

United Utilities

446

16

Haverigg; Walney Biggar Bank; Walney West Shore; Walney Sandy Gap

United Utilities

382

17

Morecambe South

United Utilities

378

18

West Kirby

United Utilities

354

19

Southport; St Annes Pier; St. Annes North; Blackpool South

United Utilities

339

20

Formby

United Utilities

326

New Brighton: England’s most polluted bathing water?

New Brighton is a beach located on the North West coast of England, on the Wirral, Merseyside. Last year, New Brighton had 1485 spills, coming in top spot for the greatest number of spills in 2023. Not only did New Brighton come top for the number of spills in 2023, but it also came second for the duration of spills, with 12,769 hours of spills, constituting a year and a half in hours!

New Brighton Lighthouse

RIVERS

Rivers are difficult to accurately calculate due to how the EDM data is presented. However, the below data shows the top 20 rivers by way of the number of sewage spills, with the percentage increase from 2022 figures.
In total, the top 20 rivers saw 55,209 instances of sewage spills across 458,725 hours in 2023! Overall, for rivers across England and Wales, it has been calculated that there have been 559,546 sewage spills in 2023. This figure means that our rivers have been hit worse than our beaches in terms of sewage pollution in 2023.
While the River Aire saw the highest number of sewage spills in 2023, the River Avon saw a dramatic increase of 77% on 2022 numbers. Each of these rivers has seen an increase in the number of spills from 2022 – a worrying trend.

Rank

River

Sewage Spills

% increase

Company

1

River Aire

4888

37

Yorkshire Water

2

River Avon

4719

77

Wessex Water

3

River Calder

4177

41

Yorkshire Water

4

River Irwell

3457

45

United Utilities

5

Unknown

3351

69

South West Water

6

River Tame

3180

54

United Utilities

7

River Severn

3057

38

Severn Trent Water

8

River Trent

2939

57

Severn Trent Water

9

River Ouse

2774

68

Yorkshire Water

10

River Derwent

2732

38

Severn Trent Water

11

River Tawe

2592

43

Dwr Cymru Welsh Water

12

River Teifi

2579

37

Dwr Cymru Welsh Water

13

River Wharfe

2456

46

Yorkshire Water

14

River Don

2231

50

Yorkshire Water

15

River Eden

2021

19

United Utilities

16

River Tamar

1999

31

South West Water

17

River Usk

1864

19

Dwr Cymru Welsh Water

18

Solent

1550

53

Southern Water

19

River Torridge

1406

49

South West Water

20

River Rother

1237

58

Southern Water

Non-Operational Sites

and sites below 90% operational

The data also includes sites that are no longer operational. During the analysis of other sections, these sites were excluded to avoid skewing the averages. There is potential that Water companies include non-operational sites in their data to improve their figures slightly. However, while these sites were excluded from other analyses, this section will specifically examine the non-operational sites.

302 sites in the data showed as no longer in operation. Anglian Water had the most sites showing as no longer operational, with 131 sites. Followed by Thames Water with 91 sites, Severn Trent with 46 sites, South West Water with 19 sites, United Utilities with 9 sites, Yorkshire Water with 5 and lastly Southern Water with 1. Wessex Water, Dwr Cymru and Northumbrian Water did not have any sites listed as no longer operational.

Other than sites that are no longer operational, there are also a number of sites that have performed less than 90% operationally. The table below shows the number of assets per water company that are performing under 90% operationally.

Number of assets under 90% operational 

Anglian Water

97

Northumbrian Water

206

Severn Trent Water

414

South West Water

175

Southern Water

144

Thames Water

152

United Utilities

262

Welsh Water

21

Wessex Water

58

Yorkshire Water

401

Total

1930

Severn Trent Water and Yorkshire Water have the greatest number of assets that are under 90% operational.

 

When sites perform at less than 90% operational, then the water companies must give a reason as to why. The table below shows these reasons, as well as which reasons are stated most by water companies.

Reason for under 90%

Number of times reason used

Access - unable to retrieve

34

capital/maintenance works

27

Comms failure/issue

543

Installation set-up/design

287

power failure/issue

175

sensor failure/issue

664

telemetry or data archival

179

The top 5 worst performing sites are below, these are sites that are above 0% operationally.

Name of site

Water Company

Operational %

Lone Valley, Waterlooville

Southern Water

9.1

Fishmarket Road, Rye

Southern Water

11

School Lane, Danehill

Southern Water

12.7

Field End Garden, Ashford

Southern Water

4

Earle Drive, Parkgate Road

Dwr Cymru

15.6

Sites with VERY little Data

Other than sites no longer operational included in the data, sites that have minimal operational % also impact the reliability of the data. With monitors working at such a low level, it means that spills are likely not caught and therefore will not be contained in the data.

Name of site

Water Company

Operational %

Lone Valley, Waterlooville

Southern Water

9.1

Fishmarket Road, Rye

Southern Water

11

School Lane, Danehill

Southern Water

12.7

Field End Garden, Ashford

Southern Water

4

Earle Drive, Parkgate Road

Dwr Cymru

15.6

Operational performance

Overview and insights

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Figure 15
Number of reported sewage discharges in Scotland between 2018 and 2022.

Title

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What does all of this mean?

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Authors
Eleanor Godwin & Annie McKelvey

What needs to happen?

Before diving deep into the sewage data, let’s take a minute to reflect on what EDM systems are and why the data is useful.

Event Duration Monitoring (EDM) is a method used to measure and record the duration and frequency of sewage overflows, and are installed on permitted assets discharging to Water Framework Directive water bodies1, which are:

Combined sewer overflows (CSOs) on the sewer network including pumping stations

  • 2. Storm overflows at the inlet to sewage treatment works (STWs)

    3. Storm discharges from storm tanks at STWs

Take immediate targeted action to tackle the highest risk pollution events.

  • End untreated discharges affecting bathing waters and popular water usage areas by 2030
  • End untreated discharges affecting high priority nature sites by 2030

Prioritise high risk pollution