The Thames Tideway Tunnel project has been formally given the green light, with the £4.2 billion ‘super-sewer’ now estimated to cost London’s water customers less than originally expected.
The Tunnel will add between £20 and £25 to average bills for Thames Water customers, with work on the 15-mile sewer running beneath the river from West to East London due to start next year for completion by 2023. Previous consumer bill estimates had pencilled in a rise of up to £80 a year. Thames Water’s five million customers already pay £7 a year towards the project as part of their bills.
The Tunnel will greatly reduce the 39 million tonnes of untreated sewage that overflows into the Thames in a typical year.
Ofwat awarded the licence to Bazalgette Tunnel, which will build the scheme for Thames Water. The project is expected to create more than 9,000 direct and indirect jobs at the peak of construction.
Thames Water chief executive Martin Baggs said strong competition for construction and financing had driven down costs. “The really good news is that cheaper finance and other efficiencies mean that this hugely important piece of national infrastructure can be built while keeping our bills at or around their current level, before inflation, for at least the next five years,” he said.
Environment Secretary Elizabeth Truss added that the announcement "brings us one step closer to finally modernising London's ageing sewerage system.
"In the 21st century, the most dynamic city in the world should not have a river that is polluted by sewage every time there is heavy rainfall."
The backers behind Bazalgette Tunnel include insurer Allianz, Amber Infrastructure and Dalmore Capital and investment firm DIF.
Bazalgette Tunnel is named after Sir Joseph Bazalgette, the Victorian engineer behind the transformation of London's sewer system more than 150 years ago.
The companies coordinating to build the tunnel include Balfour Beatty's joint venture with Morgan Sindall and BAM Nuttall; Costain's venture with the French engineering groups Vinci and Bachy Soletanche; and Spanish infrastructure firm Ferrovial in partnership with Laing O'Rourke.