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# Roman Aqueducts

## Overview
Roman aqueducts were engineering marvels that transported water over long distances using gravity, supplying cities with fresh water for drinking, bathing, and sanitation. Rome alone had 11 aqueducts delivering ~1 million cubic meters daily. Across the empire, Romans built over 200 aqueducts supplying cities from Britain to Mesopotamia. [^3]

## Key Facts
- First Roman aqueduct: Aqua Appia (312 BCE) @t[=312 BCE]
- Total aqueducts serving Rome: 11 (by 226 CE) @t[312 BCE..226 CE]
- Combined length: ~500 km (mostly underground) @t[312 BCE..226 CE]
- Daily water delivery to Rome: ~1 million cubic meters [^1]
- Last aqueduct built for Rome: Aqua Alexandrina (226 CE) @t[=226 CE]

## Engineering
- Gravity-fed: Maintained a consistent gradient (~1:200 to 1:4800) @t[312 BCE..476 CE]
- Mostly underground channels; iconic arched bridges were only ~5% of total length
- Used *opus caementicium* (Roman concrete) and lead pipes (*fistulae*)
- Settling tanks and distribution castella regulated flow
- Water also supported mining operations, milling, farms, and gardens [^3]

## Notable Aqueducts
- Aqua Appia (312 BCE): First aqueduct, built by Appius Claudius Caecus @t[=312 BCE] [^1]
- Aqua Marcia (144 BCE): Longest serving Rome at ~91 km @t[=144 BCE] [^1]
- Aqua Claudia (52 CE): Begun by Caligula (38 CE), completed by Claudius; ~69 km long @t[38 CE..52 CE] [^3]
- Pont du Gard (France, ~19 BCE): Three-tiered bridge, 49 m high @t[~19 BCE] [^2]
- Aqueduct of Segovia (Spain, late 1st–early 2nd century CE): Still standing; date debated — Géza Alföldy's reading of the dedication plaque suggests ~98 CE (Domitian), while a 2016 coin find points to 112–116 CE (Trajan/Hadrian) @t[~98 CE..116 CE] [^4]
- Aqua Alexandrina (226 CE): Last of Rome's 11 aqueducts @t[=226 CE] [^3]

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[^1]: Frontinus, *De Aquaeductu Urbis Romae* (~97 CE)
[^2]: Hodge, A.T. *Roman Aqueducts and Water Supply* (2002)
[^3]: Wikipedia, "Roman aqueduct" — https://en.wikipedia.org/wiki/Roman_aqueduct
[^4]: El País, "Age of Segovia aqueduct revised after discovery of ancient coin" (2016) — https://english.elpais.com/elpais/2016/11/01/inenglish/1477997248_304960.html