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Aqua Claudia

Aqua Claudia

This aqueduct was begun by Caligula in A.D. 38 and completed by Claudius in 52. It shared its source with the Aqua Marcia, 68 kilometers from the city. In volume of water (184,000 cubic meters per day) it was the third most capacious in the city after the Anio Novus and the Aqua Marcia. It provided water to most of the city. Impressive remains of its arches can be seen at the Parco degli Acquedotti.

Aqua Claudia

From Samuel Ball Platner, A Topographical Dictionary of Ancient Rome, rev. Thomas Ashby. Oxford: 1929, p. 22-23.

An aqueduct which (like the Anio Novus, q.v.) was begun by Caligula in 38 A.D. (Suet. Cal. 21), and completed by Claudius in 52 (unless Tac. Ann. XI.13 indicates its completion in 47; see Furneaux in loc.), who dedicated it on 1st August. After being in use for only ten years, the supply failed, and was interrupted for nine years, until Vespasian restored it in 71; and ten years later Titus had to repair it once more, aquas Curtiam et Caeruleam . . . cum a capite aquarum a solo vetustate (!) dilapsae essent nova forma reducendas sua impensa curavit. On 3rd July, 88, a tunnel under the mons Aeflanus, near Tibur, was completed. We have no records of other restorations, except from the study of the remains themselves, which show that a good deal of repairing was done in the second and third centuries (Plin. NH XXXVI.122; Frontinus, de aquis i.4, 13-15, 18-20, ii.69, 72, 76, 86, 87, 89, 91, 104, 105; Suet. Claud. 20; Procop. BG ii.3 (cf. PBS IV.72, 73); Not. app.; Pol. Silv. 545, 5461; Cassiod. Var. VII.6; Victor, Epit. iv.6; CIL VI.1256-1259, 3866 = 31963; xiv.3530).

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Additional source material

  • Ancient Library Sources (from Peter Aicher, Rome Alive: A Source Guide to the Ancient City, vol. 1, Bolchazy-Carducci: 2004) [Works cited]

    7. Rome's Aqueducts. Commentary.

    The introductory passages by Pliny and Frontinus below suggest not only the engineering accomplishment of Rome’s aqueducts—eventually 11 aqueducts totaling 500 kilometers, not including the elaborate and overlapping distribution network—but the passionate pride that the utilities of water supply and drainage could arouse in the Roman heart. Even the more sober and analytical Strabo ranks the aqueducts and sewers on par with the roads as Rome’s greatest achievements.

    The references to lead pipes by Ovid and Vitruvius support the archaeological findings, although most of the metal pipes in ancient Rome were eagerly scavenged and recycled by subsequent ages after the system fell apart. Ovid’s striking simile (a water leak in a lead pipe = blood spraying from a wound) is a window into this poet’s irreverent imagination as well as into the Roman world, combining a romantic Greek myth with an urban street scene and a Roman familiarity with spouting blood. In passing, however, it also illustrates an important feature of Roman aqueducts. After the water arrived in an open gravitational system (where it flowed in channels essentially as a stream with a cover) it entered an elevated water tank. From here the water ran under pressure in a closed system; pipes tapping the tank could take the water under streets and deliver it elsewhere to its original elevation. Although this pressure would have made it possible in lower neighborhoods to deliver water to upper stories of buildings, the Romans generally did not make use of this potential. Instead, water was made available at numerous public fountains, which, because of the pressurized plumbing, could be located at any elevation on any hill of the city, while many of the water mains could be buried beneath the streets.

    Vitruvius’s note of caution about the use of lead pipes for drinking water is interesting in light of modern concerns. In fact, the modern practice of using valves and stop-cocks, which lets the water sit in the pipes when not in use, only aggravates the problem. Although the ancient Romans occasionally used stop-valves, aqueduct water was generally left to run continuously through public and private fountains. As a result, their drinking water, even when it ran through lead pipes (as it often did), rarely paused to absorb the lead. In addition, Rome’s water is heavy with minerals that quickly coated the pipes with deposits that acted like a sealant against the lead.

    7. Rome's Aqueducts. Sources.


    If anyone should carefully calculate the abundance of waters in Rome’s public fountains, baths, pools, open canals, homes, gardens, and suburban estates, or the miles of delivery channels, the tall arcades, the tunnels under mountains and bridges across valleys, he would admit that there is nothing on earth more worthy of our wonder.

    Pliny the Elder, Encyclopedia 36.123


    [Frontinus has just finished his summary of the nine aqueducts that had been completed when he wrote his treatise in AD 97.] To so many indispensable structures of so many aqueducts compare, if you like, the idle pyramids or the many famous but useless monuments of the Greeks!

    Frontinus, Aqueducts 16


    [As a result of work carried out under the emperor Nerva in AD 97,] throughout the entire city most of the public water basins, new and old alike, have two supply lines coming from two different aqueducts. This way, a disruption to one of the aqueducts does not suspend service to the basin, which can be supplied by the back-up line.

    The city herself, queen and mistress of the world, “Goddess of lands, who has no equal and no second,” senses daily this devotion of her most dutiful Emperor Nerva, and the health of the Eternal City will improve on account of this increase in the number of tanks, supply lines, fountains, and basins. The benefits are spread among private individuals as well, due to an increase in the emperor’s grants of water; those who once stole the water in fear can now enjoy it legally as a result of such grants. Not even waste water goes unused, channeled to flush away the sources of the city’s once oppressive atmosphere. The streets have a cleaner look, the air is purer, and the odor for which Rome was infamous in days gone by has vanished.

    Frontinus, Aqueducts 87, 88


    Whereas the Greeks have the reputation for choosing good sites for their cities, giving priority to natural beauty, natural defenses, harbors, and fertile soil, the Romans provided for matters little regarded by the Greeks: the paving of roads, water supply, and sewers able to wash the refuse of the city into the Tiber. Because their long-distance roads make use of rock-cuts through hills and of artificial embankments across hollows, the wagons that use them can carry as much freight as a ferry-boat, and their sewers, vaulted with cut stone, are in some places large enough to give passage to a hay wagon. As for water, the aqueducts deliver such quantities that rivers of it flow through the city and its sewers, and almost every habitation has cisterns, piping, and running fountains.

    Strabo, Geography 5.3.8


    [Thinking, wrongly, that his lover Thisbe was dead,]

    Pyramus grabbed the sword at his waist and ran himself through,

    Then quickly pulled the reeking steel from the mortal wound

    And stretched out on his back: the blood leapt skywards

    Gushing the way a faulty pipe that’s made of lead,

    When cracked, will shoot a jet of water out a slender

    Hissing hole, spraying the air with its pulsing pressure.

    Ovid, Metamorphoses 4.119-124


    Ceramic water pipes have the following advantages over lead pipes. First, if some defect is found in the work, it can be fixed by anyone. In addition, the water in ceramic pipes is much more wholesome than water that has run through lead pipes. A probable indication of lead’s unhealthy effect on water is the toxic effect that cerussa (a white pigment made from lead) is said to have on human bodies.…

    We can find further evidence for lead’s harmful effects in the pale complexions of the people who make the lead pipes. The vapors that rise from lead when it is poured…rob the blood’s strength from the limbs of the workers.

    It would seem, therefore, that water should not be conducted in lead pipes if purity is a concern.

    Vitruvius, Architecture 8.6.10–11

    8. Rome's Individual Aqueducts, and Frontinus. Commentary.

    Aqueducts were a distinguishing feature of most Roman cities, one that was vital to basic needs, to social customs such as public bathing, and to displays of patronage. Rome, however, was exceptional for he complexity and size of its system. Extensive aqueduct archaeology in the last hundred years has revealed or elucidated a good part of the course of most of Rome’s aqueducts (rendered obscure because aqueducts ran underground for most of their length), but we are also fortunate to have a remarkable account of the city’s aqueducts written by Frontinus, a Roman senator who was appointed water commissioner in AD 97. Frontinus provides valuable information on numerous facets of the aqueducts, including the history, course, volume, elevation, and distribution network of the nine individual aqueducts that existed in his day (the Traiana and Alexandrina aqueducts had not yet been built), as well as information about the administration, laws, and maintenance of the aqueducts.

    Inscriptions also testify to the need for the continual maintenance of the aqueducts, some of which, under the patronage of the Popes, continued running long after the western empire collapsed (wrongly, numerous modern accounts have all the high-level aqueducts falling into disuse after the Goths besieged the city in the C6 AD). One aqueduct, the largely underground Aqua Virgo, never fully ceased running and provides water to fountains in the Campus Martius today, as testified by reliefs decorating the facade above Trevi Fountain, the terminus of the channel today.

    Three of the inscriptions in the sources below] can be found at Porta Maggiore, which is by far the best urban site to visit for an understanding and view of the ancient aqueducts. Called a “Gate” because it was incorporated in the Aurelian Wall in AD 271, for several centuries before the wall’s construction this site was simply a monumental road-crossing for two high-level aqueducts, one riding on top of the other on a single arcade. A right-angle jog in the aqueduct where it turned to cross the ancient Via Labicana and Praenestina roads provided the opportunity to create a sort of triumphal arch to the conquest of nature and its conqueror, the emperor Claudius. The two channels of these aqueducts (the Aqua Claudia and Aqua Anio Novus) can be seen in cross-section running through the travertine attic over the roadways. The upper two inscriptions refer to repairs that for some reason needed to be carried out shortly after they were finished.

    Although there are impressive remains of the Claudia further out of town (especially at Romavecchia, near Cinecittà), nothing else remains to be seen of it and the Anio Novus in downtown Rome. Nero, however, added an urban branch line to the Claudia, and notable ruins of this arcade can be tracked across the Caelian towards the Palatine, starting with the massive brick arcade abutting Porta Maggiore. This section has been heavily reinforced by later construction, including one in AD 201: “The Emperor Severus and Caracalla [etc.], at their own expense, repaired the Caelian hill arches from the ground up, which in many places were weak and collapsing from age” (ILS 424). In addition, a remnant of the Aurelian wall flanking the Porta Maggiore preserves a cross-section of the Aqua Marcia with Tepula and Julia channels placed atop it. The lower, brick aqueduct boring through Porta Maggiore below the Claudia is the Acqua Felice, a papal aqueduct of the late 16th century.

    In all, eight of Rome’s eleven aqueducts (two of them below ground-level) approached Rome at or near Porta Maggiore. The four longest carried water from the Anio (today’s Aniene) valley between Tivoli and Subiaco. In his summations below of each aqueduct’s statistics, Frontinus gives the distance for each aqueduct under three categories: underground channel, elevated arches, and substructure (a solid wall, used for above-ground stretches of low elevation). From these figures, it is readily apparent that the Romans preferred underground channels to the more spectacular arcades that spring to mind when one imagines a Roman aqueduct.

    [On the measurement of distances: 1,000 paces equals a Roman mile, which is about 100 yards shorter than an English mile.]

    8. Rome's Individual Aqueducts, and Frontinus. Sources.


    For 441 years after the Founding of the City [until 312 BC] the Romans were content to use what water they could draw from the Tiber, from wells, or from springs. The reverence for old springs exists to this day, since they are believed to restore health to ailing bodies, such as the springs of the Camenae … and of Juturna. Today [in AD 97], however, the following aqueducts bring water to Rome: the Appia, the Anio Vetus, the Marcia, the Tepula, the Julia, the Virgo, the Alsietina (also called the Augusta), the Claudia, and the Anio Novus.

    Frontinus, Aqueducts 4


    The Claudia and Anio Novus

    [In AD 38,] in the second year of his reign, the Emperor Caligula, who had succeeded Tiberius, began construction on two new aqueducts after it was apparent that the seven existing channels were no longer sufficient for public need and private luxury. His successor Claudius completed these aqueducts magnificently and dedicated them in the consulship of Sulla and Titianus [in AD 52]. One of the aqueducts is called the Claudia, which delivers water from the Caerulean and Curtian springs, and which rivals the Marcia in purity. The other line built by Claudius and the highest of all the aqueducts has come to be known as the Anio Novus [the “New” Anio], since it is the second aqueduct to derive water directly from the Anio River. The former Anio aqueduct has subsequently become known as the Anio “Vetus” [the “Old” Anio], to distinguish the two more readily.

    The sources of the Aqua Claudia are at the 38th milestone of the Via Sublacensis, within 300 paces down a side-road to the left. Here there are two large and beautiful pools of spring water, the Caeruleus [“Sky-Blue”] named for its color, and the Curtius. It also taps a spring called the Albudinus, which is of such purity that whenever the Aqua Marcia system needs to be supplemented, the addition of the Albudinus does not diminish the Marcia’s quality.…

    The channel of the Claudia is 46,406 paces long, of which 36,230 are underground. Of the 10,176 paces above ground, 3,076 are on arches at various points in the upper portion of the route; near town, starting at the seventh milestone, 609 paces are on substructures and 6,491 on arches.

    The Anio Novus is taken from the river at the forty-second milestone of the Via Sublacensis in Simbruine territory. Since the Anio flows through cultivated fields with rich soil, its banks erode quite easily, and as a result the stream flows muddy and turbid even without the added disturbance of rains. A settling tank was therefore constructed before the intake of the channel, where the water could form a still pool and clarify itself. Even so, whenever rainstorms pass over, unclear water is delivered to the city.…

    The channel of the Anio Novus has a length of 58,700 paces, of which 49,300 are underground. Of the 9,400 paces above ground, 2,300 are on substructures and arches at various points in the upper portion of the route; near town, starting at the seventh milestone, 609 paces are on substructures and 6,491 on arches. These are the highest arches, rising to a height of 109 feet in some places.

    Frontinus, Aqueducts 13–15


    The public works carried out by the Emperor Claudius are notable more for their size and usefulness than for their quantity. Among the most notable are the completion of the aqueducts begun by Caligula, the drainage tunnel for the Fucine Lake, and the harbor at Ostia.… He conducted to Rome on stone arches both the Claudia’s cold abundant springs (one called the Caeruleus and the other the Curtius and Albudignus) and the channel of the Anio Novus, and he distributed their waters in numerous basins of great beauty.

    Suetonius, Claudius 20



    [In AD 52] the Emperor Claudius [etc.] had the waters of the Claudia brought to Rome from the springs called Caeruleus and Curtius at the 45th milestone, and likewise the Anio Novus from the 62nd milestone, both at his own expense.

    ILS 218 = CIL 6.1256



    [In AD 71] the Emperor Vespasian [etc.] restored to the city at his own expense the Curtian and Caerulean waters, which had been led to the city by the deified Claudius but had fallen into intermittent use and disrepair for nine years.

    ILS 218 = CIL 6.1257



    [In AD 81] the Emperor Titus [etc.] at his own expense, had the Curtian and Caerulean waters, introduced by the deified Claudius and afterwards repaired for the city by Titus’s deified father Vespasian, restored with new structures, beginning from its source, after the aqueduct was ruined to its foundations from age.

    ILS 218 = CIL 6.1258


    Elevations of the Aqueducts

    All the aqueducts reach the city at different elevations, such that some can deliver water to the higher quarters and others cannot (the hills too have gradually grown higher from the rubble of so many fires). Five of the channels are high enough to reach all parts of the city, but some with greater pressure behind them than others. The highest is the Anio Novus, followed in descending order by the Claudia, the Julia, the Tepula, and the Marcia. The sources of the Marcia are in fact the same elevation as the Claudia, but the earlier builders of aqueducts laid them at a lower level, either because they had not yet fully mastered the art of surveying, or because they purposely laid the channels below the ground so that they would be less readily cut by enemies, since the Romans then still waged frequent wars against the Italians. Today, however, there are places where, whenever the old channel is ruined by age, the new channel abandons its circuitous subterranean route and crosses over a valley on substructures and arches to shorten its route.

    Seventh in height is the Anio Vetus, which likewise could have supplied the higher elevations of the city if it had been supported by substructures or arches in the places required by valleys and lower elevations. Next in height are the Virgo and the Appia; because these two originate in the fields not far from Rome, their elevation is limited from the start. The lowest line of all is the Alsietina, which supplies the Transtiber region and other low-lying locales.

    Six of these aqueducts empty into covered settling basins this side of the seventh milestone on the Via Latina, where they take a fresh breath after their run, so to speak, and deposit their load of impurities. Here too the amount of their water is measured with gauges inside the basins. Three of the aqueducts—the Julia, Marcia, and Tepula—continue the journey after the basin on the same arches, one channel on top of the other. The highest of the three is the Julia, with the Tepula and then the Marcia below it.

    After the settling basin the Anio Novus and the Claudia are carried together on the same arches (these higher than the triple-decker just mentioned), with the Anio Novus on top of the Claudia. This arcade ends behind the Gardens of Pallas, and from here their waters are distributed by pipes for use in the city. Just before this terminus, however, near the Temple of Ancient Hope, the Claudia diverts a portion of its water down another channel called the Neronian Arches. These arches extend along the Caelian hill to end near the Temple of the Deified Claudius, and deliver water to the Caelian hill itself as well as to the Palatine and Aventine hills and the Transtiber quarter.

    Frontinus, Aqueducts 18–20


    Aqueduct Maintenance and Regulations

    A few words should be said about the team of slaves assigned to the maintenance of the aqueducts. There are two of them, one the public’s and the other Caesar’s. The public body is older, bequeathed (as we said earlier) by Agrippa to Augustus, who handed it over to the state; it numbers about 240 slaves. The number of slaves on the Emperor’s team, which Claudius established when he built his aqueducts into the city, stands at 460.

    Frontinus, Aqueducts 116


    Many landowners who own fields along the route of the aqueducts illegally tap the channels, so that waters destined for public use end their journey in private hands, irrigating a garden.

    Frontinus, Aqueducts 75


    [Frontinus identifies and castigates various fraudulent practices that aqueduct workers engage in for money]. The income that the watermen collect for what they call “punctures” also has to stop. For long distances in several places, secret pipes run across the whole city under the pavement. I discovered that these pipes (which had been tapped in numerous places by a man called “The Puncturer”) provided water to all the businesses along their routes, such that only a small amount of water got through for public needs. Just how much water has been saved in addressing this problem I judge from the considerable amount of lead pulled up in the eradication of the branch-lines of this sort.

    Frontinus, Aqueducts 115


    Damage to the aqueducts is frequently caused by the lawlessness of landowners, who injure the channels in a number of ways. First, they construct buildings or grow trees on the strip of land around or above the aqueduct that by senatorial decree should be kept vacant. Trees do the greater damage, since their roots break apart both the vaulted tops and the sides of the channels. People also build their village and country roads right down the track of an aqueduct. And recently, landowners have been denying maintenance workers right-of-way to the aqueducts. All of these problems have been anticipated in the following Senatorial Decree:

    “… [I]t has been resolved that a space of fifteen feet shall be kept clear on either side of aqueduct sources, walls, and arches; around the underground sections of aqueducts and around the conduit within the city or within the built-up area around the city, a space of five feet shall be kept clear on each side, such that no one is permitted from this time forward to erect a tomb or building in these zones, or to plant trees there.… If anyone breaks these regulations, the fine will be 10,000 sesterces for each infraction, half of which will be paid to the person who brought the offense to notice, … and half of which will be paid into the public treasury.”

    Frontinus, Aqueducts 126–7

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