• DWR Cymru (Holdings) Ltd
  Pentwyn Road, Nelson, TREHARRIS, Mid Glamorgan, CF46 6LY
• DWR Cymru Cyfyngedig
  Pentwyn Road, Nelson, TREHARRIS, Mid Glamorgan, CF46 6LY
• Water Mains Sterilizing Utility Ltd
  14 High Street, BARGOED, Mid Glamorgan, CF81 8YB
• Welsh Water
  Cilfynydd Sewage Treatment, Works, Cilfnydd, PONTYPRIDD, Mid Glamorgan, CF37 4WX
• Welsh Water
  Pentwyn Road, Nelson, TREHARRIS, Mid Glamorgan, CF46 6LY