The Roman Aqueduct Project

Water runs downhill.

Simple enough. But when you have a population of 1 million living in a crowded city and your water sources are many kilometers away in the mountains, things get complicated.

The Roman Aqueduct Project breaks down the problem of providing cities with water into the following inquiries.

  • How did the Romans survey land?

  • How did they draw the water over long distances?

  • How did they cope with terrain?

  • What construction methods did they use to create aqueducts?

During this week long unit, students will build the following models.

  • the Chorobates, a Roman surveying tool

  • an aqueduct with a working water channel 30 feet long

  • a sealed "siphon" segment in the aqueduct to draw water across a valley

  • several models of Roman arches

The Romans built their aqueducts with an incredibly small gradient, less than half a degree of descent. They did this with a very reliable but very simple principle: still water will always present a surface that is perfectly perpendicular to gravity. The Chorobates was essentially a long water table with a sight that allowed the surveyor to establish a point in the distance that was level to his mark.

Siphons carried water down hillsides, across valleys, and back uphill through sealed clay pipes. Water will always seek its level and the siphon exploited this property to move water across valleys that were difficult to built bridges over.

Roman arches provided the strength and stability for bridges to convey water across lowlands and valleys where solid stone structures would have required too many resources and too much time and labor.

Works not Words

The Roman aqueduct system was one of the engineering marvels of its time and a signal aspect of Roman civic life and municipal infrastructure. It brought to life an abundance of public fountains providing clean water to the populace at no cost; it satisfied the enormous water demands for performing naval battles in the coliseum; and it made possible that luxury which is a distinctive keystone of Roman culture: the baths.

While images of the Pont du Gard and the Segovia bridge section appear everywhere that people are talking or writing about Classics, there is little to be found about Roman aqueducts in any textbooks. In fact, other than Frontinus, there is very little written on the topic at all.

What is left of the Roman water supply is an astonishing amount of actual aqueduct remains, not just the bridges that are so often photographed but hundreds of miles of well preserved underground channels winding through the hills toward Rome and other cities. We are left with many works but few words.

The Roman Aqueduct Project, a two week unit organized for a 9th grade Latin class, approached the aqueduct on its own terms: as a work. The students discovered elementary aspects of hydraulics and structural support through experimentation with a basic hydraulic level. They built a chorobates for surveying level paths for water channels. They mixed and poured concrete into trapezoidal molds in order to build a Roman arch. And they laid a water channel level for a stretch of 30 feet using ripped PVC pipe and included an inverted siphon at the end.

Some Resources

a couple of brilliant amateurs:

seminal: A. Trevor Hodge, Roman Aqueducts and Water Supply Duckworth, 2002

good ole National Geographic:

nice 3-D fly-over of Ancient Rome by Khan Academy:

a parts list for the aqueduct we built

PVC pipe ripped lengthwise

The channel was created with PVC pipe 1.5 inches in diameter. Michael and I ripped it in half on a bandsaw. It was quite flexible and we realized we needed support every about 5 feet.

Piers 5 feet apart

The pier building team cut down 9 two by fours to 6 feet each. They cut flat plywood stands for each pier and end-screwed the stands onto the two by fours. Each segment of PVC pipe was 10 feet long but the pipe would droop if it was not supported in the middle so we placed the piers 5 feet apart.

marked locations

We marked the position of the stands exactly as they were set up on the floor with masking tape and indicated their orientation. Each pier was numbered. We didn't want any shifting.


We decided to create a gradient of 1 inch every 10 feet - steep by Roman standards but forgiving in the event that our measurements and engineering were not a match for that of the Romans. So the pier team marked the declination of each pier from zero to 3 inches. That way we knew how far down to measure from dead level to get our gradient.


To measure dead level we built a modified model of an ancient Roman chorobates. It was a 4 foot piece of the ripped PVC pipe, 1.5 inches in diameter, glued to the edge of a straight, clear piece of oak so that it was true and stiff.

Looking down the channel

We wrapped the ends with clear plastic wrap so that we could see right across the top of the surface of the water. We managed to mount the chorobates on its own pier so that we would have a stable place to shoot level from.

Plumb bob

The piece of oak was attached to another perpendicular piece with a plumb bob on it. The bob was there to check against the levelness of the water. (It's all explained in Hodge's book.)

Water Control at head end and destination

the tank

Meanwhile the water control team was figuring out how to create a source tank with a valve that would start the water off at one end of the channel

the valve

the funnel

The team set up a funnel that would catch the water at the other end and send it through the inverted siphon and on to its ultimate destination.

The Roman Arch

The Roman arch team learned how to mix concrete. They also learned that once mixed, the concrete must be used up - completely. They filled pre-made forms with concrete. The forms were cut by a laser cutter from a template we found online. The students assembled the forms and sealed the edges with tape. Once the concrete set - 24 hours - they tore off the form and had very nice concrete trapezoidal prisms that fit together into a Roman arch. We got 2 kids standing on top of it.

barometric level

As it turned out the chorobates we built was not accurate enough to shoot dead level and produce such a minimal gradient, so I used a barometric level - a simple plastic tube filled with water - to mark level along all the piers. We measured down from level the specific distance listed on each pier from zero to 3 inches.

Suspending the Channel

channel elevator

We attached what we called "channel elevators" to the piers. These had some play in the precut screw holes so that we could adjust them up or down a tiny bit.

clamped channel

And we glued a dowel exactly perpendicular to the elevator for the channel to rest on. We clamped the channel to the pier.

The Inverted Siphon

We hung the water source tank well above the high point of the channel to give it a little pressure. We hooked up the funnel and inverted siphon at the other end. We opened the valve and watched the bead of the water travel down all 25 feet of the channel at a very leisurely pace, fall into the funnel, gurgle into the inverted siphon and fill it, and squirt into the receiving bucket like a little fountain.

A stroll along the waters.