The sale and transfers completed yesterday, saw Severn Trent become the full owner of three companies, Severn Trent Costain, Severn Trent Costain Holdings and Severn Trent Costain Services.
Severn Trent Costain was set up in June 2012 to offer water and waste water management for commercial and industrial water users.
The joint venture signed a multi-million pound contract in September with First Milk, making the dairy firm the first business customer to switch its water supplier for multiple sites across the UK.
As more competition is introduced for the non-domestic market, Severn Trent says its total water solutions business can leverage its skills and expertise to offer non household customers in the UK a single expert supplier for all of their water and waste water needs.
Tony Wray, Severn Trent chief executive, said: “We are in a position where Severn Trent commands the expertise, commitment and full-service skills to take this business forward for the long term.
“We look forward to continuing to work with our customers and future customers to further improve service standards and the economics of their business.”
Costain, which will make a profit of £9.1 million due to the sale, said the move was part of its continuing disposal of its PFI equity portfolio.