page_title: Roman aqueduct
section_title: Rome's aqueducts
hierarchical_section_title: Roman aqueduct / Background / Rome's aqueducts
caption_attribution_description: Français&#160;: Carte du Latium antique sur lequel figure le tracé des aqueducs de Rome. D'après un fond de carte de 1886 (G. Droysens Allgemeiner Historischer Handatlas).
context_page_description: The Romans constructed aqueducts throughout their Republic and later Empire, to bring water from outside sources into cities and towns. Aqueduct water supplied public baths, latrines, fountains, and private households; it also supported mining operations, milling, farms, and gardens.
  Aqueducts moved water through gravity alone, along a slight overall downward gradient within conduits of stone, brick, or concrete; the steeper the gradient, the faster the flow. Most conduits were buried beneath the ground and followed the contours of the terrain; obstructing peaks were circumvented or, less often, tunneled through. Where valleys or lowlands intervened, the conduit was carried on bridgework, or its contents fed into high-pressure lead, ceramic, or stone pipes and siphoned across. Most aqueduct systems included sedimentation tanks, which helped to reduce any water-borne debris. Sluices and castella aquae regulated the supply to individual destinations. In cities and towns, the run-off water from aqueducts scoured the drains and sewers.
  Rome's first aqueduct was built in 312 BC, and supplied a water fountain at the city's cattle market.
context_section_description: Rome had several springs within its perimeter walls but its groundwater was notoriously unpalatable; water from the river Tiber was badly affected by pollution and waterborne diseases. The city's demand for water had probably long exceeded its local supplies by 312 BC, when the city's first aqueduct, the Aqua Appia, was commissioned by the censor Appius Claudius Caecus. The Aqua Appia was one of two major public projects of the time; the other was a military road between Rome and Capua, the first leg of the so-called Appian Way. Both projects had significant strategic value, as the Third Samnite War had been under way for some thirty years by that point. The road allowed rapid troop movements; and by design or fortunate coincidence, most of the Aqua Appia ran within a buried conduit, relatively secure from attack. It was fed by a spring 16.4 km from Rome, and dropped 10 metres over its length to discharge approximately 75,500 cubic metres of water each day into a fountain at Rome's cattle market, the Forum Boarium, one of the city's lowest-lying public spaces.
  A second aqueduct, the Aqua Anio Vetus, was commissioned some forty years later, funded by treasures seized from Pyrrhus of Epirus. Its flow was more than twice that of the Aqua Appia, and it entered the city on raised arches, supplying water to higher elevations of the city.
  By 145 BC, the city had again outgrown its combined supplies. An official commission found the aqueduct conduits decayed, their water depleted by leakage and illegal tapping. The praetor Quintus Marcius Rex restored them, and introduced a third, "more wholesome" supply, the Aqua Marcia, Rome's longest aqueduct and high enough to supply the Capitoline Hill. The works cost 180,000,000 sesterces, and took two years to complete.  As demand grew still further, more aqueducts were built, including the Aqua Tepula in 127 BC and the Aqua Julia in 33 BC. Aqueduct-building programmes reached a peak in the Imperial Era. Augustus' reign saw the building of the Aqua Virgo, and the short Aqua Alsietina that supplied Trastevere with large quantities of non-potable water for its gardens and to create an artificial lake for staged sea-fights to entertain the populace. Another short Augustan aqueduct supplemented the Aqua Marcia with water of "excellent quality". The emperor Caligula added or began two aqueducts completed by his successor Claudius; the 69 km (42.8 mile) Aqua Claudia, which gave good quality water but failed on several occasions; and the Anio Novus, highest of all Rome's aqueducts and one of the most reliable but prone to muddy, discoloured waters, particularly after rain, despite its use of settling tanks.
  Most of Rome's aqueducts drew on various springs in the valley and highlands of the Anio, the modern river Aniene, east of the Tiber. A complex system of aqueduct junctions, tributary feeds and distribution tanks supplied every part of the city. Trastevere, the city region west of the Tiber, was primarily served by extensions of several of the city's eastern aqueducts, carried across the river by lead pipes buried in the roadbed of the river bridges, thus forming an inverted siphon. Whenever this cross-river supply had to be shut down for routine repair and maintenance works, the "positively unwholesome" waters of the Aqua Alsietina were used to supply Trastevere's public fountains. The situation was finally ameliorated when the emperor Trajan built the Aqua Traiana in 109 AD, bringing clean water directly to Trastavere from aquifers around Lake Bracciano.
  By the late 3rd century AD, the city was supplied with water by 11 state-funded aqueducts. Their combined conduit length is estimated between 780 and a little over 800 kilometres, of which approximately 47 km (29 mi) were carried above ground level, on masonry supports. They supplied around 1 million cubic metres (300 million gallons) a day: a capacity 126% of the current water supply of the city of Bangalore, which has a population of 10 million.
caption: Large scale map showing sources
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