Scope

1  This report examines the development of the Thames Tideway Tunnel. Our review of progress sought to answer the following questions:

•  What was the evidence base underpinning the objectives which were set for the Tunnel, and why was it was chosen over alternatives?

•  What is the current state of progress on the project, including expected completion and costs for Thames Water customers?

•  What are the main risks to Thames Water customers and the taxpayer during the construction phase, and how are these being mitigated?

2  Our audit approach is summarised in Figure 16 overleaf. Our evidence base is described in Appendix Two.