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This blog is a behind the scenes look at the Roman Baths in Bath. We hope you enjoy reading our stories about life surrounding the Roman Baths.

Wednesday, 11 April 2012

It's all about...... Roman aqueducts

To many people the words “Roman aqueduct” conjure up an image of huge arched monuments striding across a landscape and is one often used in pictures to portray the Romans.

But to a Roman citizen an aqueductus meant literally “water that’s lead from one place to another” or “water duct” and so the word was used for the whole length of piping or channels that carried water from source (often a spring) to a city or an industrial site. They could run great distances; one supplying Carthage in Tunisia was 132km long!

The earliest known Roman aqueduct was the Aqua Appia in Rome, built in 312BC. The Aqua Claudia also took water to Rome, but only 15km of its 68km length was raised on arches. We know quite a bit about the ones that supplied Rome as one of the men in charge of them (the curator aquarum!), called Frontinus, wrote a book on the subject.

Vallon Des Arcs, Barbegal
In Barbegal, southern France an aqueduct fed water to 16 water wheels which operated flour mills.

Most of the aqueducts relied on gravity: the water flowed from higher ground to low ground and followed a carefully surveyed gradient around a hillside. The aqueduct supplying Nimes in southern France had a gradient change of only 34cm per kilometre.

Sometimes to keep the route of the water flow at the right height, Roman engineers tunnelled through hills, and even ran siphons in watertight pipes up hill.

Castellum aquae
Once the water had arrived at a town it was held in a castellum aquae (or water tower) at the highest point of the settlement, which acted like a header tank in a modern house. This would create enough pressure to send the water through the town in smaller pipes.

In Britain we have little evidence of Roman aqueducts. The best example is near Dorchester, in Dorset, where channels along hillsides have been found that fed water to the Roman town of Durnovaria And every town and fort must have been the same, Bath included. Although the Roman town of Aquae Sulis had its hot water springs it needed cold water for the cold plunge baths, latrines (toilets), domestic supplies and perhaps even street fountains, the only source of clean water for most people. Unfortunately with all the later developments in the city nobody’s found any evidence …yet!

Pont du Gard
The Roman aqueduct now called the Pont du Gard which supplied Nimes, is 48.77m high.

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