The partners are one of two design and build joint ventures signed up by Thames Water to deliver a £2bn-£3bn investment programme through the eight2O alliance arrangement.

Originally Veolia formed part of the Costain Atkins team but pulled out last year after working on the early contractor involvement phase.

Since May last year Costain and Atkins have worked alone on the delivery phase but have now decided to draft in Black & Veatch to return to a three-way partnership.

The new pairing will work alongside the other design and build consortium -Skanska, MWH and Balfour Beatty – with MWH also acting as the programme manager and IBM the technology innovation partner.