The South West River Basin District covers over 21,000 square kilometres, and includes:
- parts of Somerset
- Hampshire, and
The River Basin District also includes the:
- urban areas of Exeter, Plymouth, Torquay, Bournemouth and Poole, the last three having populations over 250,000
- Isles of Scilly, a group of some 150 islands and rocks 25 miles south west of Cornwall.