Columbia House in Worthing will act as the company’s new south coast base and will accommodate the team which will transfer from Southern Water.
Meanwhile, Business Stream is recruiting more staff at its Edinburgh headquarters, strengthening its team of water and wastewater experts to ensure all its customers continue to receive the specialist support and care they need.
The retailer is set to be the third biggest operator in the combined Anglo-Scottish market, after it purchased the non-household customer base of Southern Water during the summer.
Following this deal, Business Stream will serve around 105,000 non-domestic customers across Kent, Sussex, Hampshire and the Isle of Wight.
Business Stream chief executive Jo Dow said: “We have a new £2.5 billion market opening on our doorstep in April and we are ideally placed to take a share of it by leveraging our knowledge, capability and experience, gained from eight years of operating in the Scottish market.
“Establishing a foothold on the south coast is a significant step in our journey towards growing market share in England. For us to truly take advantage of the opportunities on offer through the introduction of competition next year, it’s important that we have a presence on the ground from which we can lay down roots with the neighbouring business community.
“Over the coming months we’ll be making sure that we’re ready for market opening, and that we are able to deliver a seamless transition for those customers who will be transferring to us from Southern Water.”
From April, around 1.2 million businesses and public bodies in England will be able to choose their water supplier, an option only currently available to the largest water users.
Business Stream already looks after a number of large business customers based in England, including House of Fraser. The company said market opening will “present a new opportunity” for businesses and public sector organisations of all sizes to take advantage of the benefits on offer from competition.