AMP6 runs from 2015 to 2020 and Welsh Water expects to spend between £600m and £700m on its infrastructure during this period.
If the initial six year contract is extended by another five years, as there will be an option to do, the overall contract value is anticipated to be in the region of £1.5bn.
Up to four delivery alliance partners are being sought, each capable of providing both engineering consultancy and construction services across water and wastewater infrastructure.
Got a story? Email news@theconstructionindex.co.uk