Campania sits above a complex hydrology. The volcanic geology of the Phlegraean Fields, the karst springs of the Apennine foothills, and the alluvial plain of the Volturno river created a region where water was neither uniformly scarce nor uniformly accessible. The Romans identified and exploited this variety with unusual thoroughness. What they built — and what medieval communities later modified and extended — left a layered infrastructure of spring captures, gravity-fed channels, distribution tanks, and covered cisterns that remains partially traceable today.

The Aqua Augusta: Extent and Function

The largest single structure in Campania's pre-modern water system is the aqueduct known in modern scholarship as the Aqua Augusta — also called the Aqua Serino after the spring source in the Irpinian hills near Serino, approximately 30 kilometres east of Avellino. The spring emerges from permeable limestone at an elevation of around 390 metres, producing a consistent flow that Roman engineers captured and directed through a gravity channel running northwest toward the coast.

The channel covered approximately 96 kilometres by the most direct measurable alignment, though the actual route was longer because it followed topographic contours rather than a straight line. It fed a distribution network serving at least nine coastal cities and three naval installations, including the fleet base at Misenum. The main distribution point was a large tank — the Piscina Mirabilis — at Bacoli, on the northern edge of the Phlegraean Fields. The tank, largely intact, measures 72 by 25 metres and is divided internally by 48 tufa piers supporting barrel vaults. It held approximately 12,600 cubic metres of water.

Branch Lines and Secondary Systems

The Aqua Augusta was not a single pipe from source to destination. At several points along its course, branch channels split from the main line to serve individual towns. Nola, Acerra, and Pompeii all received water through documented offtakes, and the system's reach into Pompeii's street grid — documented in detail by 19th and 20th century archaeological work — provides the most complete picture available of how a Roman-era urban distribution network functioned in this region.

Settling tanks and inspection shafts were placed at intervals along the channel. These served multiple purposes: removing silt and sediment that would otherwise accumulate in the channel bed, providing access for maintenance, and allowing the flow to be interrupted at individual sections without shutting down the entire line. Several inspection shafts remain visible along the route through the Sorrento peninsula, though many are partially blocked or flooded.

Roman aqueduct remains at Sant'Egidio del Monte Albino in Campania — brick-faced channel on tufa piers
Roman aqueduct remains at Sant'Egidio del Monte Albino, Campania. The channel section preserves original Roman brick facing above a tufa pier base. The structure forms part of the branch system serving the Sarno valley. Image: Wikimedia Commons (CC BY-SA).

Medieval Modifications and Continuity of Use

The Aqua Augusta did not simply fall out of use after the collapse of Roman central administration. Parts of the channel remained functional into the early medieval period, and in several locations documentary evidence suggests active maintenance by local ecclesiastical authorities — abbeys and bishoprics that had both the institutional continuity and the labour resources to keep sections open.

The point at which Roman maintenance gave way to medieval adaptation varied by location. In the Sarno valley, an 11th-century document from the Abbey of Cava de' Tirreni records water rights connected to a channel that corresponds, in its described alignment, to a branch of the Roman network. Whether the channel was physically the Roman structure or a replacement cut along the same line is not resolved in the document, and the surviving physical evidence has not been surveyed with sufficient precision to settle the question.

The Medieval Aqueduct at Eboli

A better-documented medieval intervention is the aqueduct system associated with Eboli, a hilltop town in the Sele valley approximately 40 kilometres south of Salerno. The structure visible today includes sections of covered channel, distribution fountains, and a main cistern that postdate the Roman period based on construction technique. The mortar composition and the form of the cut stone differ from Roman-period work in the region, and a local archival source — a 14th-century notarial document — refers to repairs to the town's water conduit as a communal responsibility, suggesting the infrastructure was in use and maintained in the late medieval period.

The channel fed two public fountains documented in 16th-century descriptions of the town. One of these fountains survived into the 20th century before being demolished during urban expansion. The other is represented only by a carved stone basin, now held in the Museo Diocesano di Eboli, which retains traces of the piped inlet and overflow drain typical of municipal fountain design in the medieval south.

Medieval aqueduct channel section at Eboli, Campania — cut stone conduit with mortar joints
Section of the medieval aqueduct at Eboli, Campania. The covered channel construction and mortar composition distinguish this section from Roman-period work in the same region. Image: Wikimedia Commons (CC BY-SA).

Spring Capture Structures

Independent of the large aqueduct systems, Campania has numerous small spring capture structures — masonry enclosures built directly over the spring mouth to prevent surface contamination and to channel the outflow into a usable conduit. These range in date from the Roman period to the 18th century and are distributed across the Apennine foothills wherever limestone springs emerge.

The typical structure is a small rectangular or vaulted chamber, partially buried, with a single outlet pipe or channel leading to a storage tank or trough. The chamber is sealed above ground level to exclude surface water. Access for cleaning is through a removable stone cover or a small iron door. Many of these structures remain in use in rural areas for stock watering, though the supply is no longer considered potable by local health standards.

The density of surviving spring captures in the area between Avellino and Benevento reflects both the geology — permeable limestone producing many small springs rather than a few large ones — and the pattern of medieval settlement, which favoured dispersed rural communities over concentrated urban centres in this part of the region.

Documentation Challenges

Recording Campanian water infrastructure presents a set of problems specific to the region. The volcanic context means that some structures have been buried under pyroclastic deposits, as at Pompeii, or have subsided into unstable ground. The density of post-war urban construction along the coast has destroyed or buried many structures without survey. And the overlap between Roman, medieval, and post-medieval construction in the same locations makes stratigraphic interpretation difficult in the absence of systematic excavation.

The most reliable current inventory remains the catalogue produced as part of the Forma Italiae project, which compiled topographic and structural data for Roman-period sites in the region. Medieval-period infrastructure is less systematically covered, and there is no equivalent region-wide survey for the post-Roman centuries.

Further Reading

Archaeological site conditions change. Access to individual structures listed in this article should be verified with the relevant local superintendency or municipal authority before visiting.