The history of sewage drain pipes stretches back to some of the world’s earliest urban civilizations.The Indus Valley cities of Mohenjo-daro and Harappa,dating to 2600 BCE,featured sophisticated covered brick drains that ran along streets,lined with waterproof mortar,and connected to household latrines.These early systems included manholes for maintenance and were designed to carry waste away from residential areas,a level of engineering not seen in European cities for nearly 4,000 years.The Romans further advanced sewer technology with the Cloaca Maxima,an open-air channel that drained the city’s marshes and carried waste to the Tiber River,though this system was largely unregulated and contributed to public health issues in some neighborhoods.Following the fall of the Roman Empire,European sewage infrastructure declined into open ditches and primitive cesspits,leading to recurring outbreaks of plague and other infectious diseases until the 19th century Industrial Revolution spurred urgent reforms.

　　Today,modern sewage drain pipes face a host of unprecedented challenges.Most notably,aging infrastructure in developed nations has left an estimated 600,000 miles of U.S.sewer pipes over 100 years old,with many suffering from corrosion,root intrusion,and cracks that lead to leaks.These leaks not only waste billions of gallons of clean water annually but also contaminate groundwater and surface water sources,posing risks to drinking water supplies.Another critical challenge is Combined Sewer Overflows(CSOs),amplified by climate change-driven extreme rainfall events:when heavy downpours overwhelm combined sewer systems,untreated sewage and stormwater are discharged directly into rivers,lakes,and coastal waters.According to the U.S.Environmental Protection Agency(EPA),CSO events number between 23,000 and 75,000 each year,releasing over 850 billion gallons of untreated wastewater annually.In developing countries,where 60%of urban sewage is discharged untreated,sewage drain pipes are often inadequate,leading to raw waste flowing into streets and water bodies that exacerbate public health crises.