Northumbrian Water will raise its full-year dividend by 6% after increased water and sewerage charges helped the group maintain revenues at previous levels.The firm, which operates in the Northeast of England, has increased charges by 3%, in line with inflation. It said non-household revenue continues to be affected by the economic downturn. Total revenue for the year should be in line with last year it said.It will propose a final dividend of 8.5p a share at its annual meeting later today, giving a full year ordinary dividend of 12.79p, an increase of 6%.Northumbrian said it is still considering the details of the five-year price plan proposed by regulator Ofwat last week. Ofwat's plans would see the average water bill fall by £14 to £330 before inflation between 2010 and 2015, while leaving leave room for £21bn of investment over the five-year period, Ofwat said.