Water company · 2025
Thames Water's sewage record
8,922 discharges from 551 monitored storm overflows in 2025, for 107,230 hours in total. These are the Environment Agency's published figures.
8,922discharges
107,230hours
30monitors working under 90% of the year
The ten worst overflows
| Overflow | Into | Constituency | Discharges | Hours |
|---|---|---|---|---|
| Markyate Wastewater Treatment Works | River Ver | Harpenden and Berkhamsted | 155 | 3,531 |
| Stewkley Wastewater Treatment Works | Hardwick Brook | Buckingham and Bletchley | 143 | 3,069 |
| South Moreton | Mill Brook | Didcot and Wantage | 137 | 2,721 |
| Cirencester WwTW | Shorncote Ditch | South Cotswolds | 125 | 2,067 |
| Winterbourne WwTW | Winterbourne Stream | Newbury | 116 | 2,635 |
| Fairford STW | River Coln | South Cotswolds | 107 | 2,235 |
| East Shefford WwTW | River Lambourn | Newbury | 102 | 2,207 |
| Sevenhampton Village WwTW | Tributary of the River Cole | Swindon North | 99 | 2,055 |
| Standlake | Windrush | Witney | 98 | 2,214 |
| Marlborough WwTW | Kennet | East Wiltshire | 96 | 1,557 |
The constituencies it affects most
- Witney — 582 discharges from 14 overflows
- Bicester and Woodstock — 479 discharges from 15 overflows
- South Cotswolds — 430 discharges from 8 overflows
- Banbury — 375 discharges from 18 overflows
- Dorking and Horley — 339 discharges from 18 overflows
- Didcot and Wantage — 334 discharges from 9 overflows
- Newbury — 329 discharges from 9 overflows
- Mid Buckinghamshire — 322 discharges from 13 overflows
- Brentwood and Ongar — 307 discharges from 6 overflows
- Henley and Thame — 287 discharges from 15 overflows
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