Housebuilding company Galliford Try has been appointed as preferred bidder by Scottish Water for its non-infrastructure Quality and Standards IV framework.The FTSE 250 group said that, along with MWH Treatment and Black & Veatch, its infrastructure business will oversee design and build projects for the Scotland-based group's water and waste-water treatment programme.The contract is expected to be worth approximately £560m to the joint-venture and will run for six years."We look forward to building on our relationship with Scottish Water and bringing the benefit of our experience of collaboration across the UK water sector to Scottish Water and its customers," said Greg Fitzgerald, the group's executive chairman.Galliford Try shares were down 0.34% to 1,510.85p at 09:00 on Wednesday.