Numismatic evidence
There is very little numismatic evidence for the Roman aqueducts. Though aqueducts on coins don't provide much information, they are useful for dating purposes. However, there are a few coins of interest.For example, one coin from 114/3 BC that has caused discussion has on it's obverse side the word ROM[A], which represents the head of a female referring to Roma or Venus behind the neck a star with six rays, the value sign for a denarius (number 291 in Crawford (1974)). On the reverse side an equestrian statue is shown on a plateau supported by three arches isolated from its environment together with the capitals MN[MANIVS]. AEMILI. LEP, the name of the moneyer, see illustration 1. In 1945 M. Stuart came to the conclusion that this image was related to the aqueduct Aqua Marcia. This interpretation is not completely accepted, though, as Crawford (1974:305) states, Stuart's arguments are stronger than the other arguments that have been put forward. According to Livius the construction of a new aqueduct was started in 179 BC under supervision of the censors M. Aemilius Lepidus and M. Fulvius Nobilior. However, M. Licinius Crassus did not allow the aqueduct to cross his property, which halted the project. In the year 144 BC and with the help of a different M. Aemilius Lepidus, urban praetor Q. Marcius Rex received the order of the Senate to restore the Aqua Appia and the Aqua Anio Vetus and to build the third aqueduct. In 140 BC new objections were raised for aqueduct water to reach the Capitolinus without success: in the same year this new aqueduct, the Marcia, was put into use. This interpretation seemingly solves the problem of the relative short time of construction of an aqueduct of 92 km in length including 10 km on arcades. However, the arguments of this author were rejected by M.G. Morgan who concluded that the aqueduct line of 179 BC was never built (Kek, 1994:269).
Perhaps the most famous coin is the Marcia denarius, from 56 BC. On the obverse side the word ANCVS, possibly a reference to the fourth king of Rome, and on the reverse PHILIPPVS / AQUA MR can be seen, see illustration 2 (number 425 in Crawford (1974)). The moneyer may be Q. Marcius Philippus, but opinion leans towards it being L. Marcius Philippus (Crawford, 1974:448). The moneyer honoured Q. Marcius Rex with this coin. The moneyer also belonged to the Marcia family.
One period where coins are especially useful is that antedating Frontinus. The aqueducts constructed after his time are poorly documented. For example, one useful sestertius, dating from Trajan's fifth consulship, dates the construction of the Aqua Traiani to perhaps 109 A.D. The coin reads on the obverse IMP CAES NERVAE TRAIANO AVG GER DAC P M TR P COS V PP. The text on the reverse reads SPQR OPTIMO PRINCIPI AQVA TRAIANA S C. with an image that can be interpreted in different ways: the genius of the aqueduct, an image of the castellum aquae (the water distribution station) at the end of this Roman aqueduct, or a collection of general elements of the water supply of Rome, see illustration 3.
From Evan J. Dembskey's thesis (2009)