Here is a list of utility firms (gas, electricity, phone and water companies) who have Crystal Marks, together with a link to their website where available. The links below will open in a new browser window.
- Bournemouth and West Hampshire Water plc
- Bristol Water
- Bristol Wessex Billing Services Limited
- British Gas
- British Gas Service
- British Waterways
- Cambridge Water Company
- Eastern Electricity
- East Midlands Electricity
- EDF Energy Networks Ltd
- Electricity Supply Board (ESB)
- E-On UK (previously Powergen)
- Essex and Suffolk Water
- Eurobell (Holdings) PLC
- Firmus Energy
- GPUPower UK
- Hartlepool Water Company
- Manweb
- Mid Kent Water
- Northern Gas Networks
- npower
- Northern Ireland Electricity
- Northern Powergrid
- Norweb
- Ovo Energy
- Scottish Gas
- Scottish Hydro Electric
- Scottish Power
- Scottish Water Authority
- Severn Trent Water Limited
- Southern Electric
- Southern Water plc
- South Staffordshire Water plc
- South Wales Electric (SWALEC)
- South Western Electricity (SWEB)
- South West Water Services
- Strathclyde Water Services
- Tendring Hundred Water Services Limited
- Thames Water
- United Utilities
- Welsh Water
- Wessex Water
- Yorkshire Water
