Sewage spills from storm overflows in 2023, by water company

In each section the companies are listed alphabetically, with the equivalent data for 2022 included in brackets.

All figures have been published by the Environment Agency.

Number of hours of sewage spills from monitored storm overflows

– Anglian Water: 273,163 hours (2022: 89,514 hours)
– Northumbrian Water: 280,029 hours (107,536)
– Severn Trent Water: 440,446 hours (249,116)
– South West Water: 530,737 hours (290,271)
– Southern Water: 317,285 hours (146,819)
– Thames Water: 196,414 hours (74,693)
– United Utilities: 656,014 hours (425,491)
– Welsh Water (in England): 23,354 hours (9,470)
– Wessex Water: 372,341 hours (129,957)
– Yorkshire Water: 516,386 hours (232,054)
– Total: 3,606,170 hours (1,754,921)

Average duration of sewage spills from monitored storm overflows

– Anglian Water: 8.6 hours (2022: 5.6 hours)
– Northumbrian: 6.0 hours (3.6)
– Severn Trent: 7.3 hours (5.6)
– South West Water: 9.1 hours (7.7)
– Southern Water: 10.8 hours (8.8)
– Thames Water: 11.6 hours (9.3)
– United Utilities: 6.7 hours (6.1)
– Welsh Water (in England): 5.6 hours (3.4)
– Wessex Water: 9.0 hours (5.9)
– Yorkshire Water: 6.6 hours (4.3)
– All companies: 7.8 hours (5.8)

Total sewage spills from monitored storm overflows

– Anglian Water: 31,623 (2022: 16,082)
– Northumbrian Water: 46,492 (29,697)
– Severn Trent Water: 60,253 (44,765)
– South West Water: 58,249 (37,649)
– Southern Water: 29,494 (16,688)
– Thames Water: 16,990 (8,014)
– United Utilities: 97,537 (69,245)
– Welsh Water (in England): 4,204 (2,800)
– Wessex Water: 41,453 (21,878)
– Yorkshire Water: 77,761 (54,273)
– All companies: 464,056 (301,091)

Average number of spills per monitored storm overflow

– Anglian Water: 22.2 (2022: 15.3)
– Northumbrian Water: 30.1 (20.3)
– Severn Trent Water: 24.9 (18.4)
– South West Water: 43.4 (28.5)
– Southern Water: 30.7 (17.8)
– Thames Water: 27.9 (17.0)
– United Utilities: 45.4 (35.1)
– Welsh Water (in England): 35.0 (23.3)
– Wessex Water: 32.0 (18.5)
– Yorkshire Water: 35.9 (25.6)
–  Overall average: 33.1 (23.0)