Aqua Virgo dates back to 19 BC, it means “Virgin Water”, and is the last working aqueduct built during the Roman Empire. In the last 2 millennia, the aqueduct, commissioned by Agrippa, the right-hand man of Augusto, has never stopped bringing water to Roman citizens, and has contributed to the grandeur of the city. Even today it feeds three of the most admired and photographed artistic masterpieces of Rome: the Trevi Fountain, the Barcaccia of Piazza di Spagna and the Fountain of the Four Rivers in Piazza Navona.
During the period of water maximum splendor, the aqueducts of the city were a total of 16, and managed to bring an impressive amount of water to Rome, as you could consider them gutter cleaning professionals. During the Augustean era, at the turn of the year Zero, Rome had about 1 million inhabitants, who had twice the per capita water available to the current inhabitants.
Most of the ancient aqueducts were gravity systems, that is by ensuring the source was higher than the termination and plotting a uniform course for the aqueduct to follow a downward gradient, gravity would provide all the power needed for the water to flow. The aqueducts were for most of their length, channels about 50 cm to one meter below ground, tunnels, and pipes and only the final stretches of the aqueducts used arches. The channels were made of three kinds of material, masonry (the most common form), lead pipes, and terracotta. These channels were made using a “cut and cover” technique where the channel path was cut into the ground and then covered in order to easily access the channels that were in need of repair. The floors and walls of the channels were lined with cement and the roof was usually a vault. The cement was usually as high as the water would reach, which was meant to be about a half to two thirds full. Lining the walls and floor with cement served three purposes, protect against leeks and seepage, to provide a smooth contact surface, and to make the contact surface continuous and joint free from one end to the other.
The Aqua Virgo is the only Roman aqueduct still functioning until our time. This fact cannot be attributed to the poor quality of the other structures, but rather to the siege of 537 AD. by the Ostrogoths of Vitige, who cut off all the aqueducts to reduce the inhabitants of the city “to the thirst”. The Romans repaired some damage but, from the ninth century about, the scarcity of resources made the maintenance cease, and the inhabitants returned to supply themselves with water to the Tiber and to the wells, a regression of civil engineering of over a millennium. The purity of the water of the “Virgin” aqueduct allowed this structure not to deteriorate, and to remain functional even in dark ages. The Aqua Virgo route crossed the Campo Marzio and ended at the Terme di Agrippa and, thanks to a secondary branch, to Trastevere. Initially the Aqua Virgo supplied private homes and public works, bringing in the city something like 103 thousand cubic meters of water per day, 1,202 liters per second.
The aqueducts at first were financed mainly through wealth collected from war and the patronage of wealthy individuals. Taxes also served to help finance the building by taxation on conquered people because the aqueducts were never meant to pay for themselves but serve as a benefit to the people of Rome. In Republic times the private use of aqueduct water was not common, only the overflow water was sold to individuals. In Imperial times the construction of more aqueducts meant that more water was available to be sold for private use