Dr George McGavin and Dr Zoe Laughlin explore one of the UK’s biggest sewage works, a hidden world we rarely get to see. Processing one billion litres of wastewater a day – including what 1.7 million people flush down the loo – the program reveals the mind-boggling science behind how sewage is treated and what it tells us about how we live today. McGavin and Laughlin also discover a radical revolution in the science of sewage that is beginning to understand human waste to be a vital resource: a material full of energy, minerals, and new life. Teaming up with world-class scientists, they learn how urine can generate electricity, how the gas from excrement can fuel a car, how nutrients in waste can help solve the agricultural crisis – and even discover a new biological entity in sewage with potentially life-saving medical properties.