Northumbrian Water has announced a 93% increase in pre-tax profits on the previous year.
The firm serves 4.3 million customers in the North East
Figures announced on Wednesday show the utility firm made £108.8m in pre-tax profits compared with £56.5 for the previous 10-month period.
Higher water prices have helped to drive up the profits.
The industry regulator Ofwat has told the company that it can increase its prices by no more than 15% for the 2005-2010 period.
Northumbria Water serves 4.3 million customers in north-east England.
Speaking on BBC Radio Newcastle on Wednesday, managing director John Cuthbert said: "The interim rise was all about addressing the problems of costs not recognised in price limits previously.
"We are delivering all of our regulatory outputs and trying to make customers aware they have the lowest bills in the country.
"We also put a lot of effort into working with customers to try to make it as easy as possible for people to budget and pay their bills."
Watervoice represents the interests of customers on price, service and value for money and investigates complaints from customers.
Chairman Andrea Cook said: "We want to take a balanced view on these results.
"The company has needed to improve financability and attract investors and prevent a higher cost of borrowing being passed on to customers.
"Now the company is in a more stable financial position, we will be looking very carefully at future results to make sure that customers share in the company's success."