Balfour Beatty, Barhale, Grontmij, MMB (a joint venture of Mott MacDonald and JN Bentley), MWH and Skanska are the first partners to be confirmed.
They will deliver around half of the total investment programme. Black and Veatch has also signed as a reserve partner.
The winners make up the first of four alliances to be announced by the water company this year.
These alliances will collectively deliver every kind of work for Anglian Water, ranging from building large new water treatment works to repairing small leaks and connecting new properties to the network.
The supply chain contracts begin in 2015 and are expected to run until 2030, with a review every five years.
Over 10,000 jobs will be supported by the contracts. Schemes that they will work on over the next five years will include:
• Investing £44m to protect homes from the risk of flooding.
• Supporting growth in the region, with £192m spent improving and extending the sewerage network.
• Investing 117m on new water treatment works and pipelines, and £225m on maintaining existing water pipes and treatment works, securing supplies and helping move water around the region.
• Connecting hundreds more homes to the mains sewerage network for the first time for an investment of around £71m.
Contractors will work on a ‘total outperformance’ basis – they will only recover head office costs and earn profit when they outperform Anglian Water’s business plan.
Chris Newsome, Asset Management Director, Anglian Water, said: “These partnerships are formed on the principles of making our business as efficient as it can be, and ensuring our customers are completely satisfied with what we do for them.
“Our progressive approach to these partnerships is also fundamental to our ability to keep bills below inflation for the six years through to 2020.
“We’re committed to investing to combat the challenges our region faces, dealing with a changing climate and a growing population.
“These investments also support economic recovery and regional growth, delivered in a sustainable way that will benefit the whole of the region Anglian Water serves.
“We’ve selected partners who share our vision and are committed to the same financial, environmental and business outcomes as we are.
“Over 90 per cent of our customers supported our plan for the next five years, and these partnerships are one of the ways we’ll turn that plan into action.”