Ancient civilizations like those in Mesopotamia and the Indus Valley had early toilets and sewer systems dating back over 4,000 years.

Early sanitation systems included pit latrines and clay pipe drainage in Mesopotamia around 4000 BCE, and private toilets linked to covered sewer networks in the Indus city of Lothal around 2350 BCE. These ancient innovations show an early awareness of waste management and urban hygiene, long before flush toilets existed.