South West Water must improve its performance according to a "Water and sewerage companies' performance" report by The Environment Agency.
The Environment Agency says that last year the company was responsible for 115 major pollution incidents (including serious sewage leaks), the next highest number from a supplier was 46.
They have ranked South West Water's performance as significantly below target.
The Environment Agency also gave the company a 2 star rating, meaning that it requires improvement.
You can read The Environment Agency's full report here: