source of the city's water. Modern estimates of size of one quinaria vary over a wide range, from to of water a day, giving the Aqua Marcia a flow rate of to of water a day.

The branch to the Caelian Hill and the Aventine Hill was rebuilt completely during the rule of Trajan. Trajan's successor Hadrian restored parts of the aqueduct. Later restorations were also made during the joint rule of