Aqua Julia

Roman aqueducts: Rome Aqua Julia (Italy) Rome - ROMA Aqua Julia
For the photo's, see below
Home / the complete website

The political and social chaos during the last century of the Republic prevented the establishment of any new major water system until the Julia. As early as 33 BC it had become apparent to Octavian that he would have to reorganise the public works administration (Anderson, 1997:89). The existing four aqueducts were in dire need of restoration, as they had become an administrative and maintenance disaster.
Agrippa (c. 63 - 12 BC), holding the office of aedile, played a crucial role in the restoration and repair of the system, perhaps the most important role. He established an administration policy for the aqueducts. Acting as the 'curator aquarum', he instituted a permanent staff for the operation and maintenance of the water systems of Rome. His energy, creativity and competence formed a model for successive generations. It is generally accepted that Agrippa built the Aqua Julia in 33 BC )1.
Source and course
Julia's channel (not visible) on top of
the Aquae Marcia and Tepula
Its source was a few kilometres upstream to that of the Tepula, southeast of Grottaferrata )2 and below the roads to Marino and Rocca di Papa. This source is a number of springs that gather in a catch basin approximately three kilometres before its subterranean course in the Marciana Valley )3; Frontinus states that it was not possible to judge the volume of water at the intake because of the number of tributaries involved. According to Frontinus (1.9), the Julia was also supplemented by water from a brook called Crabra, the main supply of Tusculum )4. As the Julia ran its course, it was mixed with waters from the Tepula some three of four kilometres from the beginning of its subterranean course in the Marciana valley, passed through a piscina near Capannelle after another six kilometres, and finally rode atop the Marcia on its way into the city (See Figure D.13).
Frontinus indicates that a subsidiary branch of the Julia, diverging from the main conduit near Spes Vetus, supplied 'castella' on the Caelian. This was made possible due to the Julia's elevation that was slightly higher than that of the Marcia. The Julia also furnished the Palatine via a siphon. Frontinus lists its widespread distribution, indicating that the Julia supplied the Caelian, Isis and Serapis, Esquiliae, Alta Semita, Forum Romanum, Palatine, and Piscina Publica. The Julia's main terminus was a reservoir near the Porta Viminalis and a secondary branch delivered water to the Caelian and Aventine Hills. The aqueduct was between 22 and 23 kilometres long, and yielded 48,000 m3 per day. According to Frontinus, the Julia may have been introduced to meet the water needs of the Augustan building program. Sixty five percent of its capacity was allocated for usibus publici, of which 30% was allotted for public works. Only 3% of its total distribution supplied imperial buildings and property.

)1 The date is disputed. Dio Cassius (49.32.3) states that the line was introduced in 40 BC This suggests that the Julia was Julius Caesar's project, and finished by Agrippa after his death. This would also explain the name, which according to Evans (2000:99) would be a typical act of Agrippan self-effacement. Wright (1937) has another theory for the origin of the same; he postulates a family relationship between Caesar and Agrippa.
)2 Middleton (1892:341) states a mile north of Grottaferata, and Ashby (1935:162) places it in the region of Ponte degli Squarciarelli.
)3 This water now feeds the Marrana Mariana.
)4 This practice was stopped and the supply returned to Tusculum.

From E.J. Dembskey: The aqueducts of Ancient Rome" (master thesis 2009)

HOME More literature on more aqueducts Last modified: January, 2010 - Wilke D. Schram (


Marcia and Felice

View into the channel

Added entry

at Porta Maggiore

Porta Maggiore town side

Comparative heights

Acqua Felice

Via Prenestina

Ad Spem Veterem

Maggiore and Tiburtina

Via G. Pepe

near Porta Tiburtina

Tiburtina in
mediaeval times

Porta Tiburtina side view

Three inscriptions