The Indus Valley civilization built standardized brick sewer systems over 4,000 years ago

As early as 2600 BC, the city of Mohenjo-Daro featured a standardized urban grid with covered brick sewer systems that surpassed the sanitation of many later European cities. These drains maintained a consistent slope of 1:100 over distances of 700 meters, ensuring that gravity alone cleared waste from 900 household wells. Offset junctions were strategically placed to trap sediment and prevent blockages in the main street cesspits.