The four-year framework, which gets underway in January, is expected to be worth £20m a year with the option to extend for a further four years.
Under the terms of the agreement, MUS will work closely with Affinity Water to carry out design, programming, customer and stakeholder engagement, as well as adoption of value-engineering options and end-to-end delivery.
Jim Arnold, Chief Executive of Morrison Utility Services, said: “We are delighted to have been chosen as the service partner for Affinity Water across its three water supply areas.
“The scope of work will include design and build responsibility for over 100km of mains renewal per annum, as well as over 600 developer services projects, and associated connections, each year.
“We will work closely with Affinity Water to ensure a collaborative and agile approach based on a foundation of safe operations, strong customer focus and innovative ways of working.”