| Affinity Water Limited | 29 | 2026-03 |
| Amentum (UK) Ltd. | 31 | 2024-09 |
| Ameycespa (Awrp) Odc Limited | 16 | 2020-07 |
| Ameycespa (East) Limited | 9 | 2023-06 |
| Anglian Water Business (National) Limited | 26 | 2026-03 |
| Anglian Water Services Limited | 59 | 2026-03 |
| Biffa Municipal Limited | 45 | 2026-03 |
| Biffa Waste Services Limited | 44 | 2026-03 |
| Bristol Water PLC | 59 | 2023-01 |
| Bywaters (Leyton) Limited | 53 | 2026-03 |
| Castle Water Limited | 20 | 2026-03 |
| Clear Business Water Limited | 22 | 2024-10 |
| Commercial Services Kent Limited | 21 | 2026-03 |
| Cornwall Energy Recovery Ltd | 23 | 2025-03 |
| Cory Environmental Limited | 27 | 2025-12 |
| Cumbria Waste Management Ltd. | 46 | 2025-03 |
| Donald Ward Limited | 25 | 2025-09 |
| Ds Smith Recycling UK Limited | 55 | 2025-12 |
| Dwr Cymru Cyfyngedig | 25 | 2026-03 |
| Enovert South Limited | 55 | 2022-12 |
| Enva England Limited | 36 | 2026-03 |
| Erith Contractors Limited | 54 | 2020-09 |
| Fcc Environment Services (UK) Limited | 22 | 2024-12 |
| Fcc Recycling (UK) Limited | 38 | 2025-12 |
| H W Martin Waste Limited | 31 | 2026-01 |
| Hafren Dyfrdwy Cyfyngedig | 47 | 2025-03 |
| Hills Waste Solutions Limited | 31 | 2026-04 |
| Hughes and Salvidge Limited | 34 | 2026-03 |
| Industrial Water Jetting Systems Limited | 24 | 2023-09 |
| Integrated Water Services Limited | 33 | 2021-09 |
| Keltbray Environmental Ltd | 50 | 2021-04 |
| Kent Enviropower Limited | 27 | 2025-12 |
| Kier Integrated Services Limited | 43 | 2025-12 |
| M J Church (Plant) Limited | 46 | 2026-03 |
| Merseyside Energy Recovery Ltd | 26 | 2025-03 |
| Mick George Earthworks Limited | 59 | 2025-12 |
| Mick George Recycling Limited | 45 | 2025-12 |
| Mitie Waste & Environmental Services Limited | 54 | 2026-03 |
| Northern Ireland Water Limited | 14 | 2026-03 |
| Northumberland Energy Recovery Ltd | 23 | 2025-03 |
| Northumbrian Water Limited | 36 | 2026-03 |
| Nuvia Limited | 29 | 2025-12 |
| Personnel Hygiene Services Limited | 37 | 2026-03 |
| Portsmouth Water Limited | 13 | 2026-03 |
| Powerday PLC | 27 | 2026-01 |
| Reconomy (UK) Limited | 47 | 2024-12 |
| Renewi UK Services Limited | 37 | 2026-03 |
| Rhodar Industrial Services Limited | 53 | 2025-12 |
| Rhodar Limited | 46 | 2021-12 |
| Riverside Resource Recovery Limited | 27 | 2025-12 |
| Ronald Hull Jnr. Limited | 27 | 2023-09 |
| Rsk Environment Limited | 37 | 2026-03 |
| S. Norton & Co Limited | 17 | 2022-12 |
| Scottish Water Business Stream Limited | 26 | 2026-03 |
| Severn Trent Services Operations UK Limited | 33 | 2026-03 |
| Severn Trent Water Limited | 40 | 2026-03 |
| Smith's (Gloucester) Limited | 59 | 2021-09 |
| South Downs Waste Services Limited | 5 | 2021-06 |
| South East London Combined Heat and Power Limited | 30 | 2025-12 |
| South East Water Limited | 41 | 2026-03 |
| South Staffordshire Water PLC | 28 | 2021-09 |
| South West Water Limited | 30 | 2025-09 |
| Southern Water Services Limited | 42 | 2026-03 |
| Stirling Water Seafield Limited | 15 | 2025-06 |
| Suez Recycling and Recovery UK Ltd | 48 | 2025-12 |
| Sutton and East Surrey Water PLC | 46 | 2024-09 |
| Thames Water Utilities Limited | 60 | 2026-03 |
| UK Waste Management Limited | 42 | 2026-03 |
| United Utilities Water Limited | 14 | 2026-03 |
| Veolia Es Birmingham Limited | 45 | 2025-12 |
| Veolia Es Hampshire Ltd | 38 | 2025-12 |
| Veolia Es Merseyside & Halton Limited | 34 | 2025-12 |
| Veolia Es Nottinghamshire Limited | 37 | 2025-12 |
| Veolia Es Sheffield Limited | 36 | 2025-12 |
| Veolia Es Shropshire Limited | 40 | 2025-12 |
| Veolia Es South Downs Ltd | 34 | 2025-12 |
| Veolia Es Southwark Limited | 39 | 2025-12 |
| Veolia Es Staffordshire Limited | 42 | 2025-12 |
| Veolia Water Outsourcing Limited | 38 | 2025-12 |
| Viridor Avonmouth Waste Services Limited | 10 | 2026-03 |
| Viridor Enviroscot Limited | 28 | 2022-03 |
| Viridor Oxfordshire Limited | 57 | 2025-09 |
| Viridor Resource Management Limited | 49 | 2024-09 |
| Viridor South London Limited | 41 | 2025-03 |
| Vws (UK) Ltd | 43 | 2020-12 |
| Water Plus Limited | 37 | 2026-03 |
| Water Plus Select Limited | 17 | 2022-03 |
| Wessex Water Services Limited | 18 | 2025-12 |
| West London Energy Recovery Ltd | 25 | 2025-03 |
| William Tracey Limited | 42 | 2026-03 |
| Yorkshire Water Services Limited | 30 | 2026-03 |