Costain has won a 10-year contract with Severn Trent worth an estimated £400 million.
Work on AMP5 will start in April 2010. Costain is one of eleven firms picked for the framework which has been awarded a year early in order for the companies involved to be able to begin on their design and planning work.
Full details of the 2010-15 contract will be finalised once the outcome of Ofwat’s price review is known.
Costain chief executive Andrew Wyllie said: “This is a significant win for Costain and it is particularly pleasing to announce a framework contract win from a new customer.
“The group is the recognised leader in the water sector and this award from Severn Trent underlines our outstanding reputation in the industry.”