How did Public Sanitation Develop
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.
Early History of Sanitation
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.
In the 3rd millennium BCE, clay pipes now extended into sewer systems within structures. In the Indus, urban planning included public sewers are evident at sites such as Lothal. In Mesopotamia, at about the same time, sewers with clay pipes were used, although the system does not seem to be centralized. Rather, houses would have vertical shafts that would send waste far below a house. Alternative systems moved waste and waster water out of structures and into larger drains or cesspits.
Late Antiquity of Sanitation
One of the most elaborate ancient sewer systems was the Cloaca Maxima, which was a large-scale sewer system built for Rome. It was likely constructed already in the Etruscan period and became more elaborate during the Roman period. The Roman covered what was an initially open-air sewage system into a closed system. The underground system connected public baths and latrines. The system of aqueducts that connected to Rome, where there were seven aqueducts by the 1st century CE, brought freshwater supplies to the city. The elaborate waste removal and freshwater supply to Rome enabled it to grow substantially in size, reaching over one million people, making it the first city to likely reach that size.
In the Medieval Period, cities began to utilize small open canals along streets to move waste water out of cities. Sometimes natural stream were utilized to move waste away from a city, although this had the detrimental result of polluting water downstream. By the late Medieval period, however, cities were developing more sanitary policies and becoming administered by central municipalities that managed issues of waste water and the provision of drinking water. public latrines were constructed, although by the 16th centuries flush toilets were also utilized at least by the royalty.
Interestingly, in Japan and China, there was a different solution to the problem of human waste. In this case, there was a collection system where human waste was used to fertilize agricultural fields. In Western states, this did not develop because of the dependence on cattle, while in Japan and China cattle were not as integrated into the agricultural process.
By the 16th and 17th centuries, it was determined that potassium nitrate needed for gunpowder could come from human waste. European cities soon used their public latrines as a way to collect materials that would then be used to create potassium nitrate used for gunpowder. This industry helped to create a way to recycle and remove waste from public areas, helping cities to become more health and grow by the late Medieval and early modern periods.
Overall, however, the system that was already in ancient societies in the Near East, Asia, and Rome largely did not develop further until the modern Industrial Age in the late 18th and 19th centuries. The main innovation that developed was the introduction of mechanical pumps. Large sewer systems could not be created with better tunneling technologies and pumping stations could be used to move water irrespective of the terrain slope. Cities during this time became unhealthy as populations expanded and migrated to cities. By the late 19th century, chemical treatment was used to treat waste water, mostly in the form of using chlorine to treat water. Sand filtration was also used to clean water, with the introduction of sand filtration to London in 1829.
The world's first modern sewer system was in London. It was developed to have 450 miles of sewers that used large tunnels that applied a combination of gravity and pumping stations to move waste water. This enabled London to handle its very rapidly growing population, reversing the many problems, such as typhoid, the city had with disease outbreak in the earlier part of the 19th century. Paris in the late 19th century also witnessed large-scale expansion. Similar to London, the mixture of waste water with drinking water made typhoid and other epidemics widespread. The city responded by building 600 kilometres of aqueducts that brought potable spring water into the city, while underground sewers were built that drained waste, with dirty water used to help flush sewage away from the city. Other cities in North American and Europe built similar systems during the 19th century. By the early 20th century, chemical treatment of sewage became more established.
In the 20th century, sewage treatment plants began to be established with the innovation of using sludge or natural bacteria as part of the waste water treatment process. In this case, tanks or pools of waste water would be treated with bacteria to help breakdown waste. Chemical treatment was also utilised.