Among the largest and most striking works left by the Romans, the aqueducts were designed in Rome in the 5th century. B.C. because the water supply of Rome, which until then had relied on the Tiber or the wells, was no longer sufficient. Rome was being transformed into the largest metropolis of all Antiquity and beyond, so it was decided to build an aqueduct that connected a source and brought fresh water to the city. The first aqueduct was the Aqua Appia, built in 312 BC. at the behest of the Consul Appio Claudio, the same who gave the name to the famous Via Appia. Over the years, other larger aqueducts were built. In total there were twenty-four aqueducts, which transported over 1 million cubic meters of water every day, covering a total of over 400 km of pipelines.
Trajan had contributed to making Rome the most sophisticated city in the world. There were all the comforts that a man could desire and, unique in the world, his network of aqueducts. The Roman aqueducts were unrivaled, they were able to bring pure water directly to the homes of a million citizens.|
Every day something like 900 million liters of water arrived in the city traveling through the provinces of the empire along impressive arched buildings, some of which are still visible today, an absolutely avant-garde system, which would no longer be overcome for centuries and centuries.
Rome was a very hot city and this convinced its emperors to strive to equip it daily with an adequate supply of water. And for this reason it is so rich in fountains. In those days, every patrician house had one.
Many scientists of the time thoroughly analyzed the water. Vitruvius had the idea of boiling it and analyzing its debris. He considered the contaminations of the different types of soil and studied with obstinate passion all the plants that lived in contact with water, from the joints to the reeds, from far away to the papyrus.
During the empire of Trajan a commission was set up that dealt exclusively with the water supply, led by the engineer Frontino. Frontino, Trajan’s engineer specialized in aqueducts, was a very meticulous man. He wrote a detailed work on his activity, and it is thanks to the written one that we now know everything about the Roman aqueducts.
Scholars have already discovered long ago that the Romans did not take water from the Tiber river, but from the hilly springs. Since the water came from above, it could be easily channeled and flow downstream.
Gradually the Roman engineers gained enormous experience which allowed them to overcome any obstacle. A water network of tunnels and aqueducts 416 km long was built.
The construction work began with an in-depth study of the slope, in order to determine the right inclination of the aqueduct. Before entering the pipes, the water passed through special purification tanks. Here the flow was slowed down so that impurities were deposited on the bottom. During its journey, several kilometers from the hills surrounding Rome to the center of the city, water could pass through tunnels like this.
There were many similar galleries dug almost everywhere around the capital. The aqueducts of the time were built so well that many of them are still in operation today.
Roman engineers used a particular technique: they dug a well every 32 meters as the conduit proceeded through the hill. This allowed them to keep under control the inclination of the tunnel by measuring it with the plumb line, but when the duct came out of the hill, in addition to making it maintain the right slope, it had to be supported.
For this reason, stone walls were built to support him during his long journey to the city.
There was another problem, however: the conduit often had to travel several meters above the ground. In that case, the construction of a retaining wall was too expensive.
The solution was the arch. This is a very classic semicircular Roman arch, it is more than 5 meters wide and is built with stone blocks. There are 27 of them along the arch.
The engineers used a formwork, a wooden structure on which they assembled the arch. Once the stones were placed, which were wedged together, they applied cement and continued construction to the top. When the central stone was in its place, the wooden frame could be removed.
The arch built with blocks of stone cut to size and wedged between them supported itself, unloading its weight on the base. At that point the bulk of the work was done.
Now the aqueducts could cross the wider valleys, however the arched structure still seemed rather fragile and a way was studied to make it more solid. The problem of stability had already arisen when the aqueduct had to cross a river, and had been solved with special stone blocks, which diverted the current, but too high an arch could become unstable.
That’s why the Romans set the maximum height of an arch on 21 meters. To build other taller aqueducts, orders of arches were superimposed on that which rested on the ground. One of them, built with three orders of arches, reached 55 meters.
The need arose to give a watertight seal to the aqueduct. Thus a waterproof cement was discovered with which the walls of the duct were coated, a material composed of a particular volcanic sand mixed with lime, which guaranteed a perfect seal.
This is the conduit that transported water to ancient Rome. It had an extraordinary flow, in its time it sent hundreds of millions of liters of water into the city every day, and the special material with which it was coated made it waterproof throughout its length.
But why build these colossal architectures instead of using a simple pipe? Of course the Romans could have transported the water to the city through a system of pipes, which unraveled on the surface, but the pressure inside the pipes would have been a big problem. For this reason, they went down to gently lower the water downstream into aqueducts like this. It’s a brilliant idea, a brilliant way of solving the problem. However the conduit was covered and this prevented the water from evaporating and being contaminated.
In any case, passing an aqueduct through a deep valley, a crevasse, was expensive. That is why many cisterns were built. The water was channeled into special pipes and came out on the other side thanks to the pressure. This is the pipe that comes from the first part of the aqueduct. The water descends into the valley and then rises towards a cistern, from where it is conveyed to the next branch of the aqueduct.
Once in Rome the water ended up in three different tanks. The first was reserved for ordinary needs, the second for public toilets, and the third for private houses that paid a special tax. The money from that tax was used to finance the public water supply.
The control of the water supply gave each emperor confirmation that the life of its citizens was in his hands. Trajan had given his subjects an arena a new forum, a shopping center and a regular supply of water.