Quintus Marcius Rex was appointed praetor peregrinus in 144 BC under the consulship of Servius Sulpicius Galba and Lucius Aurelius Cotta.

The two major aqueducts, Aqua Appia and Aqua Anio Vetus, were greatly damaged and many fraudulant misappropriation parts reduced the flow. Then the Senate commissioned Marcius to repair the channels of two aqueducts and stop the diversion. Additionally, he was given the task to build a bigger aqueduct.

He was granted 8,400,000 sestertii for construction, and since his praetorship term expired before the aqueduct's completion, it was extended for a year. The canals, named Aqua Marcia to honor Marcius, formed the hill Capitolinus by arches while secondary branches made the hills Caelius and Aventinus

In 143 BC, under the consulship of Appius Claudius Pulcher and Quintus Caecilius Metellus Macedonicus, the Decemvirs consulted the Sibylline Books and found that it was the Aqua Anio Vetus's water that led to the Capitolinus, and reported their conclusions to the Senate. Three years later, 140 BC, under the consulship of Quintus Servilius Caepio and Gaius Laelius Sapiens, this matter was again brought before the Senate. The decemvirs' opinion prevailed, and then the aqueduct's water was conducted at the hill Capitolinus.

Regardless the ignorance was an art of precision or by chance, the aqueduct was buried in Rome as they had to support the city in wars against the Italics.

Children:
F Marcia Regina av MARCII -150--95
M Quintus Rex av MARCII -148--75

Barn:
Marcia Regina av Marchii, född -150, död -95