Aqueducts were a waterway system that could transport water over long distances right into the city, providing running water, indoor plumbing, and a sewer system. Aqueducts were built as a system of arches for stability and to take advantage of gravity for continuous flow of water. Aqueduct arches were only built in areas where digging or surface grades were problematic, like valleys.
Aqueducts were built from a combination of stone, brick, and a volcanic cement called pozzuolana. The arches we associate with aqueducts actually only make up about 30 miles of the 260 miles of the entire system. The rest of the waterway system is made of channels bored through rock or beneath the surface of the earth to carry water for maximum convenience. From the channels, it flowed into massive cisterns called castella that held the water and were connected to a large system of lead pipes that carried the water throughout the city.