The Roman Empire flourished in large measure because it built logistics infrastructure to support civil administration of conquered territories. Roman roads enabled commodities and other goods from interior estates to be transported to coastal ports for shipment to the capital, and also provided an efficient network for moving its legions among the growing roster of provincial seats. But those provincial cities, often in arid areas, could not have grown beyond the size of military garrisons without the water supplied by Roman aqueducts.
In The Aqueducts of Rome (De Aquis urbis Romae), the patrician, provincial governor and three-time consul Frontinus summarizes the importance of water supplies to the growing capital as the Empire expanded. Appointed water commissioner in 97 A.D., Frontinus followed his habit of studying first-hand the practical details of the operation he had been appointed to supervise, rather than relying on assistants. Noting his “zeal” for the task, Frontinus counted and measured everything from the numbers of various plumbing parts ordered to the projected volume of water flowing through each conduit into the city, comparing estimates to actuals, professing “astonishment” when the numbers didn’t foot, and suggesting a comprehensive program of written permits, engineering requirements, and construction certifications to make sure private users did not take more water from the aqueducts than they were authorized to obtain.
The result is an early treatise on civil administration. Appointed by a reform administration, Frontinus covers the history of the construction of the aqueducts since the first in 312 B.C., the construction and maintenance of collecting pools and related plumbing, the regulation of water usage by private parties, and extensive illicit market in water, which he attributes to the “dishonesty of the water-men, whom we have detected diverting water from the public conduits for private use.” Frontinus also suggests officials in preceding administrations might have been involved in financially-motivated decisions—an indication that corruption in the finance and construction of public service infrastructure is as old as human history.
During a recent trip to Rome, this reviewer paid a visit to the Porto Maggiore, where Roman roads and aqueducts converge for convenient viewing. The conduits of two of Rome’s later water lines are clearly seen atop an arched gate where the Via Praenestina and Via Labicana once entered the city. Begun in 38 A.D. by the Emperor Claudius, the structure was “completed on the most magnificent scale” to carry the aqueducts Claudia and Anio Novus, which augmented the city’s supplies with water from the Monti Simbruini about twenty miles outside Rome. The cross-section highlights how Roman aqueducts were built with a very slight incline over long distances because they relied on gravity to move water downhill. While Roman engineers plotted straight lines for roads, they plotted meandering courses for moving water from source to city, a practice Frontinus calls the “art of levelling.”
Roman aqueducts have proved durable. The Acqua Vergine, still operational, supplies water to the Trevi Fountain, and the first-century A.D. aqueduct at the Pont du Gard in southeastern France, built to carry water to the Roman colony of Nemausus (present-day Nîmes), served as the backdrop for the start of Stage 17 of the 2019 Tour de France.
Modern impressions of aqueducts formed from the surviving segments supported by archways overlook how construction changed to reflect changes in security concerns as Rome developed from city to Empire. Early builders, Frontinus writes, “purposely sunk their aqueducts in the ground, in order that they might not easily be cut by the enemy, since frequent wars were still waged with the Italians.”
Drawing from Frontinus’ successful campaigns on the Rhine and Danube frontiers and his tenure as governor of Britain, Stratagems (Strategemata) collects examples of military strategies intended to motivate Roman officers to conceive similar operations for their own commands; numerous cases involve how to ensure supplies of food and water, or which ruses might convey to enemies that a force is well-provisioned despite shortages of essential supplies. Frontinus devotes Book III Chapter VII to ideas “On Diverting Streams and Contaminating Waters,” such as Caesar’s use of subterranean channels to cut off the water flow from the springs supplying Cadurci during one of his Gallic campaigns in 51 B.C. Romans were already experienced water engineers by that time, as neighboring populations came to learn.
To Frontinus, building and operating public works such as roads and aqueducts was not just a practical requirement of military conquest and provincial administration. Such achievements displayed the glory of Rome as a civilization. Reflecting on the Claudia and the Anio Novus, which outside the city flowed across some of the highest arches in the Roman aqueduct system at 109 feet, he writes in De Aquis, “with such an array of indispensable structures carrying so many waters, compare, if you will, the idle Pyramids, or the useless, though famous, works of the Greeks.”