Engineering Rome

Washing the City Clean with the Latest Technology

Water Structures and the Human Health

In this wiki article, Roman aqueducts, sewer system, and baths will be discussed with respect to the health of the Roman citizens during the Roman Empire, 31-500AD.

Roman Health
The Romans greatest asset was their army. In order to have a strong army the men had to be healthy. The idea that the government had to keep their people in the army healthy led to public health. In the beginning, all knowledge of human health came from military doctors but quickly grew to benefit civilians. The Roman Empire soon put a great focus on public health by incorporating public baths and hospitals. But for this paper, I will focus more on the preventable measures of public health rather than the hospitals. Some examples of preventable measures the Roman Government incorporated were a sewer system in Rome, 11 aqueducts providing fresh water to its citizens, and widespread public baths. The Romans initially disregarded Greeks’ ideas of health. However, as all Rome’s doctors were of Greek origin, prisoners of war, Rome soon followed the Greek practices when it came to public health and hygiene. Cleanliness was very important to the Romans and they was known to hide the poor citizens who held bad hygiene with a grotesque smell away from the wealthy citizens. Within Rome the drinkable water and well as water to bathe in was sourced from far out springs channeled through those 11 aqueducts while all their waste went directly into the Tiber River flowing right through the city, by way of Rome’s sewer system. Rome’s sewer System, Cloaca Maxima, was viewed as Rome’s greatest achievement had it not been the contents of the sewer itself. During the Roman Empire, discussed in the article, The Anatomy of Rome from Capital to Cloaca, many literatures related the human body to Rome and its sewer. The sewers were seen as the guts of Rome.

The Roman Sewer System “Cloaca Maxima”
In 768-264BC, before the Roman Empire, a civilization called the Etruscans built a canal to drain the low-lying regions of where Rome is today. It was constructed around 600BC and was originally an open canal. During the Roman Empire, the foundation of the canal was there and the Cloaca Maxima was built on top of it. The difference was that instead of an open canal, the Cloaca Maxima was covered. This change was important because it not only concealed the contains and smell from the public but was also more hygienic. Rainwater also went to the Cloaca Maxima because the waste was so concentrated it would clog the sides and start to erode them. All that waste and water was then drained into the Tiber River. (GIVE A MAP OF THE MAXIMA)
A sewer system in Rome was of great importance to the public in terms of their health because there was such a high population density that their waste needed a large, systematic way of leaving the city. Rome was the first city to contain that many people in such a small amount of land, no other city came close until London centuries later.
The types of materials used in the sewer system is hydraulic concrete. This concrete contains lime and pozzolan. Pozzolan is a substance that if ground into dust form and mixed with water creates a concrete-like form. During the Roman Empire it was found in volcanic ash from the Puteoli region. (2) That combination of lime and pozzolan creates its own carbon dioxide, which is needed to dry concrete which allows the hydraulic concrete to dry in wet conditions, even in water. (1) This use of pozzolan allowed for faster construction because the workers did not have to wait for the concrete to set before submerging it in the water. There was a lot of bad stigma related to Cloaca because of the reason the people used it in the first place. Not many citizens wanted to know about what happened to the waste they made in their latrines. The stigma was so bad that if a person discussed the sewer system or made references to it, that person would have a lower status in society. Since there was such distaste for the sewer system and it was expensive to install almost no private homes’ latrines were connected to the sewer line. Instead, many citizens of Rome used chamber pots in their private homes, which were then emptied in the street in the evening where slaves and other lower class men cleaned the streets while they slept. (3)
The Cloaca Maxima is still operational today, with continuous repairs and upgrades to it, and flows a combination of waste and rainwater into the Tiber River. However, with heavy rains the Maxima overflows and floods the forum.

Roman Aqueducts
Most aqueducts transported water from springs to cities or towns. Springs provided the cleanest water in terms of lacking the most particles, lime, and other harmful pollutants. River water was not as clean because the substances at the ground of the river are soft and can easily be carried along by the river. A major way people relied on knowing what water was safe to drink and what water was harmful was that if people drinking water from a source and they looked healthy then that water was safe to drink, if they looked sickly then that water was unsafe.
There were 11 functional aqueducts (JUST GO THROUGH THE LIST)
Due to the space for this paper I will mostly discuss Acqua Claudia, Acqua Antionus, and Aqua Virgo.
Acqua Virgo is the only of the 11 aqueducts still in use today. It was originally built in 19BC and was weathered by disuse and lack of maintenance after the fall of the Roman Empire in 467AD. However, it was fully restored and used today under the new name of Acqua Vergine. The legend behind the name Acqua Virgo is that a young virgin directed tired Roman soldiers to the springs, located on the eighth milestone of Via Collatina today. The men were so grateful they named the aqueduct that supplies the water from that spring after her. The water is known to be in its most purest form, like a virgin, with no lime build up along the walls of the channel.
-materials used for the aqueducts, labor, etc.
The aqueducts have two sections: above ground and below ground. The above ground parts of the aqueduct have arches of opus reticulatum (brick), mortar, and opus caementicium (concrete). Due to the design of arches, skilled engineers were employed in order to keep the structure standing and therefore the process was slow and expensive. The inside of the arch consists of concrete which is made of a mixture of sand and mortar with various types of rumble from other structures like broken pottery to give it bulk. By using this type of concrete it could form a uniform mass that arches could be made from using a wood frame. (2) The use of concrete allowed for faster construction time, cheaper materials, and unskilled labor could be used. Concrete has good compressive strength but poor tensile strength, which is why arches were common. Arches help convert tension to compression by having a curved top instead of a flat one. Today, if you see parts of structures, especially arches, in Rome you’ll probably also see steel reinforcements to keep the structure standing. After the concrete forms the internal structure of the arch on the aqueduct, brick is then laid on the exterior part of the wall with mortar, made of pozzolan, lime and water, used to hold them in place.* Today, you mostly can only see the concrete interior because the brick facade has weathered away over the years. (SHOW PIC) At the top of the aqueduct, water is flowing which is covered by a concrete top to help protect it from the sun evaporating all the water and various animals contaminating the water. Within the aqueduct, a hydraulic plaster was put in place halfway up in order for the water to pass without deteriorating the aqueducts foundation. However, when water continuously flows through the aqueduct, lime, calcium, and other particles begin to build up and changes the shape of the channel. With enough build up the aqueduct can overflow. (DISCUSS THE AQUEDUCT HOMEWORK ON HOW MANY YEARS IT TAKES TO OVERFLOW) but because the cover of the aqueduct is so heavy and high, above the ground maintenance is difficult and expensive so it happened very infrequently.
*Side note on brick: Bricks were not used often before the Roman Empire because there was no demand for a quick timeline and standardized shapes. The art of stone masons were in demand to create art instead of designing the functionality of a wall. Once the Roman Empire started the empire grew dramatically and required quick timelines for necessary structures like houses, aqueducts, and public baths. The use of standardized brick increased as many contractors could work on a project and use many different suppliers. There were sun dried and fired bricks. However, once fired bricks became easier to make it replaced sun dried bricks because they were more durable and had a greater load-bearing capacity. (2) If the brick cannot sustain the structure the aqueduct will collapse and the people cannot receive the necessary fresh water. Before the Roman Empire, brick-like objects were used called opus reticulatum (reticulated work). These faux bricks were made of tuff and in the shape of a pyramid. These pyramid bricks, along with concrete, were used in Ostia Antica. To form a wall they were placed at a 40* degree angle downward in the concrete with the point facing into the wall. What we see today is the square bottom of the pyramid. However, the walls were not structurally sound built this way and often developed cracks along the concrete that held the pyramid bricks together. (SHOW PIC)
The parts of the aqueducts built below the ground are the best for many reasons. The first and most important reason is that the aqueducts were easier to build. It does not take expensive engineers and stone-cutters to dig in the ground and carve a channel. Workers on below ground aqueducts were usually cheap, unskilled workers and, sometimes, slaves (slaves were expensive to fed, clothing, sheltered, and maintain their health). With many unskilled workers the building process was quick. Every 25 to 50 feet the workers would build a shaft (SHOW PIC) in order for easy access during construction and for continuous maintenance of the channel. Like in the above they applied a hydraulic plaster for water to pass without hurting the structure but build up was a problem. Maintenance workers would go through the shafts, that usually had wood or rock blocking the entrance to detract curious animal, to clear the lime build up away.
the same hydraulic concrete used to create Cloaca Maxima is used to build the aqueducts. The second reason that below-ground aqueducts were best was through military advantage. One military strategy to attack a city was to cut of their food and water supply, this will weaken the city to its core. So by having the aqueducts under the ground many soldiers cannot find them and knock them down to cut off the supply of fresh, drinking water. One drawback to having an under-ground aqueduct, specifically the Aqua Claudia, is that there are many cave ins and workers must dig a new path, a bypass, quick in order to restore the water flow. Another negative is that the underground usually went the same path, or followed the same path, as a nearby river so it wasn’t straight.

The Romans knew a few very basic yet important concepts of constructing an aqueduct. One concept was that the source of the water must be at a higher elevation than the destination of the water in order to incorporate gravity and make that water transportation possible. Another important concept was that within the structure of an aqueduct required as few corners and curves as possible. Aqueducts made by the Romans were, for the most part, one line at a linear slope. (SHOW HAND DRAWING OF AN EXAMPLE) This gave maximum benefit to the designers, laborers, and citizens. If there were sharp corners and turns the force of the water hit that part of the channel would be so continuous and great that it would damage, and with enough time destroy, the structure and slow the flow of water to its people. If there must be turns and transitions, they must be smooth and with little curvature. The aqueduct also needs to be at the correct linear slope. At the time, Vitruvius wrote that the ideal slope would be 0.50%. However, with today’s technology a man named Trevor Hodge in 1992 disagreed with Vitruvius’s claim and stated that the ideal slope is 0.15-0.30%. That difference of 0.2% does not seem to be great at first glance but over a stretch of many kilometers that is the difference of getting the water to the right location.
-show what is left of the aqueducts
-draw from the knowledge the Romans knew of the land to design the aqueducts
-how successful were the aqueducts?
-who used them? how often? how were they maintained/cleaned?
The aqueducts brought (FIND EXACT AMOUNT) of water to the City of Rome and surrounding areas. The water was used for public fountains, publics baths, and private baths for wealthy residents.
-how clean was the water transported?
If the water was taken from a spring the water was very clean and remained clean through the channels of the aqueduct. However, within the city of Rome along with many surrounding cities lead pipping was used in the transportation of water. (PUT PIC OF LEAD PIPES FROM OSTIA). In a collection of 10 books titled De Architectura written by a man who went by Vitruvius, he stated that lead pipping brought ill health to humans because it was observed that people who worked with the lead construction all began to have poor health. However, it was believed that the lead pipes brought little to no harm to the citizens who drank the water from the pipes because the water was constantly flowing through them. Whereas today where we have plumbing and pumps for our water it stops flowing through the pipes when we turn off the water. When the water stops flowing it sits in the pipes and can pick up the particles.

Roman Public Baths
The Roman Empire had a large focus on public baths because they believed the health of its citizens was important to managing an empire. All public baths were free or cost very little to the public, making cleanliness easily accessible and a priority to the people. Since there are too many to discuss all of them I will focus on two major baths, the Baths of Caracalla and the baths in the ruins of Ostia Antica. I will also touch on the use of private baths in Ostia Antica.
The Baths of Caracalla was built in 212-217AD in Rome and it was the largest structure made in a hundred years. The Baths of Caracalla are also the best preserved thermal complexes and can tell us a lot of what health was like during the Roman Empire. Even though the project was completed in such a short time it was a massive undertaking. The total cost was around 1,400,000,000 denarii (~ $7 billion today) in order to build the actual complex, the roads leading to the complex, and the branch of a major aqueduct in order for the baths to maintain water. Aqua Marcia was the aqueduct they made a branch off of in order to provide the water to the baths. Over 9,000 laborers worked daily for those five years. Many materials were used in creating the thermal complex including brick, rock, concrete, metal, timber, and marble. Marble was very expensive because it was a luxury rock and it had to be shipped from far outside Rome. The bath complex is something similar to today’s luxurious spa and gym. There were two workout stations on both sides of the bath and an olympic-sized swimming pool at the main entrance. In the center, there are the cold baths (frigidarium) leading to the room temperature baths (tepidarium) that end in the hot baths (calidarium). (PROVIDE THE DIAGRAM) To give a more descriptive view of visiting the baths, the frigidarium was measured at 58 by 24 meters with eight colossal, granite columns holding up the vaulted ceiling. The floors were covered with marble in many intricate and colorful patterns. There were four large cold baths on each wall where one attached to the olympic-sized pool through a waterfall. In order to maintain good temperatures throughout the complex, especially in the hot baths, good wall insulation was needed through the use of concrete and brick because it retained heat and cool air. In order to create a hot temperature in the calidarium an underground heating system is used which will be discussed more in-depth the Ostia Antica baths. It was in use until 537AD when an enemy destroyed the above ground portions of the aqueducts leading to Rome, cutting off all fresh water supplied there.
In Ostia Antica, only the very wealthy citizens had its own plumbing which means having the use of toilets in the home. The middle and lower classes had two options to remove waste. The first option was to carry a chamber pot and empty it into the streets when it got full for the slaves to clean every night. However, doing that was not a hygienic solution so public baths were made to provide those sorts of services to the public.
-how the structure was built in mind of the comfort of its recipients
-audience importance when building structures
Within the ruins of Ostia, there were several functional public baths. Within one of them the engineer set it up to have an expansive wall of double-glazed, double-paned, windows facing the south in order to maximize the sun’s heat. This section of the bath was good especially during the winter where citizens could easily get into a warm space because the windows and few brick columns, placed to the support the structure, brought in the heat from the sun and trapped it inside. Along that wall contained the sauna and the Calidarium, where the hot baths are located. The solar energy was not the only energy used to heat the baths, slaves and other workers set fires underneath the baths (SHOW PIC) which heated the floors to provide comfort for the guests and along the walls in each room there were hollow bricks channeling the heat directly into the room (SHOW PIC). The publics baths all incorporated the use of pyramid bricks into the walls.
The baths had an elaborate construction with several rooms. The overall importance for the baths was that they would stay at the right temperature and provide comfort to the people in the rooms. In order for that to occur there was a mixture of using geothermal energy, solar energy, and combining it with engineering.
-describe specific design(s) of public baths and what made their structures so important to Rome’s citizens
-give photos you take and blueprints/layouts of the baths

Why these Structures and Concepts are Important Today
Many structures, including the Pantheon in Rome and the Duomo in Florence, are a mystery today with how they were constructed. We can only theorize how they were built using the knowledge we have accumulated over the centuries. When the Cloaca Maxima, aqueducts, and the Baths or Caracalla were being built the engineers did not use complex equations that engineers today can rely on. Trial and error was a strategy incorporated as well as studying other successful civilizations such as the Greeks. The structures still standing today are the few ones done correctly and are continuously being restored today and the structures with errors were quickly destroyed. The Romans not only followed the Greeks with construction but with public health practices.

(3) Hodge, A. Trevor (1992), Roman Aqueducts & Water Supply, London: Duckworth,

  1. A Comparison of the Chemical and Engineering Characteristics of Ancient Roman Hydraulic Concrete with a Modern Reproduction of Vitruvian Hydraulic Concrete
  2. The Economic Impact of Technological Advances

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