Nov 23 (Reuters) - Water utility Severn Trent (SVT.L) brought forward its time target of implementing actions to improve river quality by 16 years on Tuesday, days after Britain launched a major investigation into sewage treatment. Severn Trent, one of the country"s largest water companies, said it was not yet clear what the scope or likely outcome of the investigation would be given it was in its "very early stages". "There has been much discussion recently about the quality of our rivers and coastline. Rivers are key to our supply chain and, although we don"t own our region"s rivers, we take our role in protecting and caring for them seriously," Severn Trent said. "Our rivers are currently the healthiest they have been since the Industrial Revolution, but more needs to be done. That is why we plan to fulfil all our actions set out in the Environment Act to improve river quality in a nine-year timeframe, rather than the 25-year target," the company added. The comments came together with Severn Trent"s half-year results, which showed a 13.8% rise in profit before interest and tax to 255.6 million pounds ($342.48 million) for the six months ended September. ($1 = 0.7463 pounds) Reporting by Shanima A and Muvija M in Bengaluru; Editing by Milla Nissi