How Did Roman Aqueducts Work? Explained for Students

Step by step

Find a source: a spring, river or lake higher than the city.
Survey the route so that it slopes downhill all the way, following the land's contours.
Dig a covered channel, lined with waterproof mortar, mostly below ground.
Cross valleys on arched bridges and tunnel through hills, keeping the slope.
Let mud settle out in tanks along the way.
Divide the water in a distribution building (castellum) into pipes for fountains, baths and paying customers.

How gentle was the slope?

Very gentle. The aqueduct to Nîmes in France, which crosses the Pont du Gard, runs for about 50 kilometers but drops only around 12 meters in total. Keeping such a precise slope over long distances was a remarkable feat of surveying.

How many aqueducts did Rome have?

The first, the Aqua Appia, was built in 312 BC. By the 3rd century AD, the city of Rome was served by eleven major aqueducts. Around AD 97, the water commissioner Frontinus wrote a book describing how they were run and the problems of leaks and water theft.

Questions students and teachers ask

Did Roman aqueducts use pumps?

No. They relied on gravity and a carefully planned downhill slope.

Why were most aqueducts underground?

An underground channel kept the water clean and cool, protected it from enemies and was cheaper than building arches.

Are any Roman aqueducts still standing?

Yes. The Pont du Gard in France and the aqueduct of Segovia in Spain are among the best preserved, and parts of Rome's aqueducts survive in the Park of the Aqueducts.