In a survey on humanity’s most vital inventions, the British public ranked the flush toilet above mobile phones, beds, shoes, and the combustion engine. Who can blame them? In a well-sewered world, we are protected from many of the infectious diseases that contributed to making our unplumbed ancestors’ lives nasty, brutish, and short. Cholera, hepatitis, polio, and the diarrhoeal diseases that continue to kill more people globally than acts of violence all implicate faecal transmission. It seems only rational to dispatch our excrement as quickly as possible in a cleansing torrent of water.