What were aqueducts made of?

An aqueduct was a water pipe and the Romans used ceramic for the pipes. The ceramic kilns of the tenth legion have been found in present day Israel along with their aqueduct building equipment. Do not be mislead by the external supports of the water pipe. They were at times arches in more than one tier or layer, and they were generally made of stone and concrete. However, they were only supports for the water pipe, no matter how striking they may appear. Remember too, that most Roman aqueducts were underground and they were constructed of ceramic piping.