With the beginning of settled life, a new problem arose as people began to live in one place throughout the year. That problem was public sanitation. With increased population, the need to adequately remove human waste and maintain relatively clean water supplies became an increasing challenge. By prehistory, this challenge was addressed in societies, with increasing sophistication as cities grew and became more complex.
Sanitation is evident in the earliest settled societies. In the Indus Valley, Mesopotamia, and Iran, evidence exists for the use of sewers and clay pipes for removing human waste. With ceramics being present in societies by 7500-7000 BCE, this technology became utilized for making clay pipes could safely transport waste. By the Neolithic in the Near East in the 7th and 6th millennia, vertical shafts were used for waste disposal and wells had begun to be utilized within villages for getting freshwater .