Northumbrian intends to offer “national coverage” to eligible customers in England and Wales.
It already provides water and sewerage services to a portfolio of customers in Scotland, and announced in March that it was rebranding as ‘Wave’.
The firm wants to become the retail supplier for customers in the Northumbrian Water and Essex and Suffolk Water regions via the retail exit mechanism.
Meanwhile, Thames holds a current water supply licence and is applying for the new water supply and sewerage licence.
Five companies have now applied for licences, since Ofwat opened the application process for those wishing to provide retail services in the new market at the beginning of April.
Scottish retailer Cobalt Water applied last week, and Castle Water and Clear Business Water have also submitted applications.
Retail services cover activities such as billing, reading water meters and customer services and advice. Companies interested in providing such services will need to hold a water supply licence (WSL) or a water and sewerage supply licence (WSSL).
At present, businesses, based wholly in England and who use more than five mega litres of water – which means a water bill of about £9,000 – per year can choose their water retailer.
However, when the market opens the remaining estimated 1.2 million businesses, charities and public sector organisations will either be able to stay with their existing supplier, or shop around and switch.
Once open, the new market will link to the existing market in Scotland, and will be the largest retail water market in the world, delivering an estimated £200 million of overall benefits to customers and the UK economy.
Other Scottish suppliers, including Scottish Water subsidiary Business Stream and new entrant Everflow, have also told Utility Week they are considering buying into the English market when it opens.