UTILITY firm Northumbrian Water will float on the full stock exchange by the end of September, the company confirmed last night.

The Durham group floated on the London Stock Exchange's junior index, the Alternative Investment Market, in May, but announced at the time that its intention was to apply to join the main list within six months.

The water company's stock brokers announced yesterday that the company was switching the date it reported its operating figures to the City to March 31, to bring it in line with the rest of the UK's utility companies.

Northumbrian Water has enjoyed a honeymoon period since returning to the stock exchange for the first time in nearly a decade.

The initial float price of £1 a share quickly rose to 112p and has since fluctuated between 107p and 115p.

Northumbrian was one of ten water and sewerage companies floated in 1989 after being privatised, but it left the market in 1995.

A £2.21bn deal struck at the weekend saw a consortium of investors, led by Deutsche Bank, take control of the company, with Suez retaining a 25 per cent interest.

Deutsche Bank, brokers Collins Stewart, and Ecofin, an investment advisory firm specialising in utilities, bought the company through their joint vehicle Aquavit.

The company will probably feature in the FTSE 250.

Sector regulator Ofwat is due to publish a consultation document in October which will eventually determine the prices water companies can charge for the next five years.

That process, likely to take nine months, will have a large influence on Northumbrian Water's future share price and annual dividend.