Over eight years, the new water partnership deals will together be worth over £530m.
Previously, clean water network repairs and maintenance were delivered by one contractor.
Under Yorkshire Water’s new Water Services Partnership, contracts are divided into five lots – in order to drive innovation, competition, customer service and support the water company in meeting efficiency targets.
Both firms will deliver emergency and planned reactive work and metering services for the water company – with MUS covering the east of the region, and Network Plus covering the west.
Network Plus will also deliver developer services work across the whole region.
The contracts start in July and initially last for four years, with a further four-year extension option.
Director of water at Yorkshire Water, Neil Dewis, said: “The new contracts will create a competitive, dynamic, and resilient service that rewards exceptional performance, nurtures innovation, and supports us in delivering against our AMP7 performance commitments.
“The new Water Services Partnership will allow us to improve on many levels. In the longer term it will help us to drive more innovation in the industry, and in the shorter term it will allow us to continuously improve service for our customers and for Yorkshire as a whole.”