The intriguing BBC documentary ‘The Five Billion Pound Super Sewer’, following the construction of a new sewage system beneath the Thames, concludes this week on BBC Two.

The three-part programme, filmed over three years, has given viewers a remarkable insight into Thames Water’s ambitious project to tackle the problem of overflows experienced as London’s population continues to grow.

Once completed, the Thames Tideway will consist of a 16 mile long network of tunnels, connecting to 34 combined sewer overflows, diverting waste to a treatment site in East London.

The final part of the documentary series airs on BBC Two at 9pm on Tuesday 31^st July.  The first two instalments are available on-demand through the BBC iPlayer.