How Were Roman Aqueducts Made?

Engineering

The Roman Aqueducts were one of the earliest engineering feats of the first millennium, built and used for a period of 500 years (from the first century A.D. to the Fall of the Roman Empire, generally thought to be 476). The aqueducts were constructed under specific guidelines according to the type of water source, the length of construction and levels of terrain they would sit on, and were built anywhere from 10 miles in length to over 60 miles long. The city of Rome had 11 aqueducts that were used for its water supply during this time.

Construction

The Roman builders used a mixture of limestone and volcanic dust to construct the aqueducts, while others contained some brick that was used to guard against leaks. To insure the water supply remained untainted by animal carcasses or other disease carrying pathogens, many of the tunnels were constructed underground. A base of stones was used, and then boards were used to build the form. The outsides of the ducts were often plastered for further protection, and mortar was used to support the arch. Many scholars cite the intricacy of the planning and surveying--well ahead of its time--as the reason the aqueducts were so successful.

Function and Demise

When the engineers reached a hill, they would sometimes install a siphon to funnel the water up an incline, and the water was often carried by the aqueduct from its source to the needed area by gravity alone. Engineers built smaller water supply lines, called leats, that were used to carry water to industrial sites such as mines.
During the fourth and fifth centuries, events that contributed to the decline of the Roman Empire also led to the decline of the aqueduct. Barbarian invaders often cut off the aqueduct lines, and still others fell into disuse as populations moved and smaller cities in the empire fell. Aqueducts that were built outside of the empire continued to be used after the empire declined, however.
Parts of some aqueducts can be viewed to this day. The most famous examples include the lengthy Eifel Aqueduct, which ran nearly 60 miles and remains partly intact. Another largely intact aqueduct can be seen at the Pont du Gard in Southern France.

References

• Roman Aqueduct history