In 2014, 62 million tonnes of raw sewage polluted the tidal River Thames in London. In fact, we’re still relying on the engineering brilliance of Sir Jospeh Bazalgette and his sewers from over 150 years ago. To upgrade this Victorian sewerage network and stop it overspilling into the river, over £4.2bn was invested in a new state of the art sewer tunnel that spans 25km beneath the city of London. Imagineering and engineering.