Aqueducts (General)

The aqueducts are impressive constructions demonstrating how the ancient Romans’ mastery of engineering. Ruins of various aqueducts can still be seen all around the city. Prior to their construction, there was no need for them as Rome was naturally blessed with many water sources, including springs and the Tiber River. As the city and population grew rapidly, harvesting water from more distant sources became necessary and aqueducts were constructed.

In short, the aqueducts served as conduits. Using the natural flow of gravity, they directed water streams originating from lakes, rivers, and springs from distant locations into the heart of the city. Four aqueducts were built during the Republic period. The oldest being the Aqua Appia, built in 312 BCE by Appius Claudius, as it was customary to name the project after the individual responsible for it. The Aqua Appia was16.5 kilometers in length, its course following a path similar to the modern Via Prenestina. A portion of the structure still stands in the area of Porta Maggiore. 

In 272 BCE, the second aqueduct was constructed. The Aqua Anio Vetus was much longer, reaching nearly 63 kilometers and drawing water from the Anio River. Following the conquest of Carthage, the expansive Aqua Marcia was built in 144 BCE. Completing the aqueduct projects from the Republic, the Aqua Tepula was completed shortly after in 125 BCE after the conquest of Greece. 

A century later, under the reign of Emperor Augustus, the existing aqueducts were expanded and modernized, and three additional aqueducts were constructed. The new projects were the Aqua Julia (33 BCE), the Aqua Virgo (19 BCE), and the Aqua Alsietina (2 BCE). The Aqua Virgo was particularly important as it supplied water to the Campus Martius, an area that Augustus was developing during the same period. 

In 38 CE, Emperor Caligula began two new aqueducts that were later completed by his successor Claudius in 52 CE. They were the Aqua Anio Novus, the second branch drawing from the Anio River, and the Aqua Claudia. The monumental arcades of the Aqua Claudia are well preserved and can be seen stretching out for miles at the Parco degli Acquedotti. 

To direct water to his baths constructed on the Esquiline hill, Emperor Trajan built the Aqua Traiana in 109 CE. With a similar idea, Emperor Caracalla completed the Aqua Antoniana in 213 CE to supply water to his own bath complex. The history of many of these aqueducts was written by the author and engineer Frontinus at the end of the 1st century CE. In his treatise, he studied the construction systems developed through time and described the recommended maintenance methods. 

The aqueducts are some of the most memorable constructions from Ancient Rome. The monumental arches can still be seen standing in some parts of the city and in other locations that were part of the Empire, including France and Tunisia. There were 11 aqueducts built in Rome during the Republic and Imperial periods. 

The precision of the technical system of the aqueducts proves that the ancient Romans were masters of engineering. The aqueducts consisted of artificial channels that collected water from natural sources, including rivers and springs, and led them into the city. These sources had to be located at a higher elevation so the water could flow down gradually. The inclination of the channels was minimal, decreasing around five meters in height per kilometer.

In total, the channels stretched an incredible 500 kilometers, the majority of the construction being underground. The arches that are still visible today consisted of only 5% of their total length. The arches supported the water channels above them, as they were built to cross areas where it was not possible to dig underground and, depending on the condition of the terrain, to maintain the gradual inclination fundamental for the aqueducts to function. Importantly, the arches represented the power and confidence of the Romans as they were exposed and vulnerable to enemy attacks.

Throughout time and as technology improved, the Romans were able to harvest water from further and even higher locations. The higher the location of the source, the higher the water entered the city, which allowed the supply of water to the hills of Rome. An example is the Baths of Trajan, located on the Esquiline Hill and fed by the Aqua Traiana built in 109 AD. 

The immense amount of water from the aqueducts constantly flowed into the city. After being used for its primary purpose, it was directed into secondary locations, including shops and laundries. Some of the water was stored in cisterns to rotate and substitute the water in the pools of the imperial baths. 

Finally, the water was discharged into the sewer lines and drained into the Tiber River. The aqueducts were directly connected to the development and success of the Roman civilization. According to author and engineer Frotinus, when all 11 aqueducts were working, they supplied the city with 1 million cubic meters of water provided to a population of nearly 1 million people. 

Bibliography

• Butler, Howard Crosby. “The Roman Aqueducts as Monuments of Architecture.” American Journal of Archaeology 5, no. 2 (1901): 175–99. https://doi.org/10.2307/496768.
• Chanson, H. “Hydraulics of Roman Aqueducts: Steep Chutes, Cascades, and Dropshafts.” American Journal of Archaeology, Volume 104, Number 1. January 2000. https://doi.org/10.2307/506792
• Morgan, M. H. “Remarks on the Water Supply of Ancient Rome.” Transactions and Proceedings of the American Philological Association 33 (1902): 30–37. https://doi.org/10.2307/282585.
• Romolo Augusto Staccioli, Acquedotti, fontane e terme di Roma antica, Roma, Newton & Compton, 2005.

Rome’s aqueducts:

• Aqua Appia
• Aqua Claudia
• Aqua Iulia
• Aqua Marcia
• Aqua Tepula
• Aqua Traiana
• Aqua Virgo
• Aqua, Alexandrina
• Aqua, Alsietina
• Aqueduct Anio Novus
• Aqueduct Anio Vetus