| Secure Shredding & Destruction Ltd | Epping | 2025 |
| Secure Shredding Limited | Bedford | 2025 |
| Secure Waste Limited | Swindon | 2012 |
| Secure Weee Recycling Ltd | Hollinwood | 2012 |
| Secureshred Scotland Limited | Lochgelly | 2008 |
| Secureshred(Ni) Limited | Newry | 2015 |
| Secureshreduk Limited | Cardiff | 2020 |
| Security System Reclaim Ltd | Newport | 2018 |
| SED Verde Ltd | Stanmore | 2020 |
| Seed Environmental (Ireland) Limited | Manchester | 2019 |
| Seed Environmental Limited | Manchester | 2013 |
| Seed Sowers Trust | Buckfastleigh | 2000 |
| Sefco Holdings Limited | Pewsey | 2013 |
| Sefton Waste Management Limited | Liverpool | 2024 |
| SEG Global Limited | Milton Keynes | 2026 |
| Seingaffs Ltd | London | 2025 |
| Seisdon UK Ltd | Staffordshire | 2006 |
| Seitnians Ltd | London | 2025 |
| Sekalb Nine Limited | London | 1941 |
| SEL Metals Limited | London | 2024 |
| Selby Removal Solutions Ltd | Selby | 2023 |
| Select Environmental Services Limited | Reading | 2000 |
| Select Plumbing and Water Solutions Ltd | Littleborough | 2026 |
| Selective Environmental Solutions Limited | Bishop Auckland | 2017 |
| Selective Leasing Limited | Evesham | 2008 |
| Seletia (F) Limited | Manchester | 1992 |
| Seletia (HW) Limited | Manchester | 2024 |
| Self-Lay Limited | Sandy | 2020 |
| Selsey Holdings Limited | Coventry | 2007 |
| Selwych Limited | Cirencester | 1994 |
| Seneca Environmental Solutions Ltd | London | 2008 |
| Senior Waste Removals Ltd | Bury | 2015 |
| Sensa Waste Solutions Ltd | Sheffield | 2014 |
| Sensei Pro Flow Services Ltd | Milton Keynes | 2026 |
| Sensys Limited | Biggleswade | 1999 |
| SEP Drainage Ltd | Middlesbrough | 2024 |
| Separator Solutions Limited | Dudley | 2019 |
| Septic Tank Experts Ltd | Bournemouth | 2019 |
| Septic Tank Services Ltd | Lochgilphead | 2020 |
| Septic Tanks North West Ltd | Carnforth | 2026 |
| Septiclean Limited | Cricklade | 2017 |
| Serenity Pet Funeral Services Ltd | Bolton | 2019 |
| Serious Waste Management Limited | Burton-On-Trent | 1995 |
| Servega Limited | Northolt | 2012 |
| Service Corporation Ltd | London | 2014 |
| Service in Separation Ltd | Inverurie | 2023 |
| SES Business Water Limited | Surrey | 2016 |
| SES Water Limited | Redhill | 2016 |
| Settal Cleaning Service Ltd | London | 2023 |
| Settlingstones Services Ltd | Hexham | 2012 |
| Seven Cities Recycling Limited | Syston | 2014 |
| Seven Days Rubbish Ltd | London | 2022 |
| Seven Hills Tyres Limited | Sheffield | 2025 |
| Seven Hills Waste Management Ltd | Darwen | 2024 |
| Seven Locations Ltd | Horley | 2023 |
| Seven Seas Water (BVI) Holdings Limited | London | 2011 |
| Seven Seas Water (Panama) Holdings Ltd | London | 1988 |
| Seven Ways Environmental Services Limited | Rhyl | 2001 |
| Sevenaxservices Ltd | St. Albans | 2026 |
| Sevenoaks MR Limited | Halstead | 2025 |
| Sevenseas International Limited | Harrow | 2009 |
| Severn Asbestos Removal Ltd | Kidderminster | 2022 |
| Severn Insulation Co. Limited | Clos Marion | 1974 |
| Severn River Environmental Limited | Cardiff | 2018 |
| Severn Softeners Ltd | Gloucester | 2019 |
| Severn Trent Green Power (Ardley) Limited | Oxfordshire | 2006 |
| Severn Trent Green Power (CW) Limited | Chipping Norton | 2012 |
| Severn Trent Green Power (Hertfordshire) Limited | Chipping Norton | 2008 |
| Severn Trent Green Power (Rbwm) Limited | Chipping Norton | 2010 |
| Severn Trent Green Power Composting Limited | Chipping Norton | 2003 |
| Severn Trent Services (Water and Sewerage) Limited | Coventry | 2014 |
| Severn Trent Services Defence Limited | Coventry | 2004 |
| Severn Trent Services Operations UK Limited | Coventry | 2000 |
| Severn Trent Water Limited | Coventry | 1989 |
| Sewage Treatment Services Limited | Highbridge | 2003 |
| Sewells Fuels Ltd | Brentwood | 2023 |
| Sewer Conservation Group Limited | London | 2026 |
| Sewer Intelligence Ltd | Richmond | 2020 |
| Sewer Maintenance Company Limited | Lytham St. Annes | 2004 |
| Sewer Rehab Services Ltd | Pudsey | 2025 |
| Sewer Sealing Services Limited | Fleet | 2000 |
| Sewer Serve Solutions Ltd | Manchester | 2019 |
| Sewer Services Ltd | Durham | 2025 |
| Sewer Solutions Limited | Sheffield | 2014 |
| Sewer Surveys UK Ltd | Cardiff | 2015 |
| Sewerco Limited | Alderley Edge | 2025 |
| Sewerline Ltd | Leeds | 2020 |
| Sewerpro Ltd | Enfield | 2019 |
| Sewertech Ltd | Leeds | 2016 |
| Sewerworx Limited | Rotherham | 2024 |
| SF Drainage Solutions Ltd | Shipley | 2025 |
| SF Skip Hire Ltd | Stoke-On-Trent | 2023 |
| SFP Automation Limited | Oxfordshire | 1989 |
| SFS Grab Hire Ltd | London | 2023 |
| Sfsp Limited | London | 2026 |
| SG Removal Services Ltd | Birmingham | 2017 |
| SGB Drainage Limited | Bolton | 2021 |
| SGB Water Engineering Ltd | London | 2019 |
| Sgbp Facades Ltd | London | 2020 |
| SGG Environmental Solutions Limited | Birkenhead | 2018 |