Water in Roman culture was often characterized as symbolically pure, and it was frequently utilized in cleansing rituals within Roman religion. Furthermore, water was widely believed to possess healing capabilities.

Roman ideas regarding the medical powers of water were, to some extent, influenced by ancient Greek tradition. Like ancient Greek doctors, Roman physicians maintained that hot or cold baths could help balance the humors of the body. Therapeutic baths were extensively promoted by the Methodic school of medicine, whose adherents included doctors such as the 1st-2nd century CE physician Soranus of Ephesus. Methodic doctors were known for frequently recommending pleasant treatments, which perhaps contributed to their acceptance of medical baths. It is likely that the prominence of bathing as a standard recreational activity helped motivate the popularity of medicinal baths amongst the Roman public.

Roman medicinal use of water was further rooted in ancient Italic tradition, in which healing springs were also present. The conflict between native Italic custom and Greek borrowings manifested itself in the diverging views regarding remedial baths held by different authors, such as the 1st-century CE naturalist Pliny the Elder and the 1st-century CE encyclopedist Aulus Corenlius Celsus. Pliny rejected Greek medical practice and instead advocating for more traditionally Roman combinations of herbalist therapies and bathing. In contrast, Celsus accepted Greek theories and often propagated the dietetic ideals of Greek physicians.

Religion

Sanctuaries In the Aeneid, the 1st-century BCE Roman poet Virgil describes the shrine of the oracle Faunus, mentioning that the sound of a "sacred fountain" ("") is audible at the site.Virgil. Aeneid. 7.81-84. Later, the 4–5th-century CE Roman author Servius the Grammarian provides further commentary regarding this scene, adding that "there is no spring that is not sacred" ("").Servius the Grammarian. Commentary on the Aeneid of Virgil. 7.84. Numerous Roman sanctuaries were constructed at the sources of rivers, such as the shrine at Lake Bracciano near the start of the Aqua Traiana. This type of religious site was most common in the western portions of the Roman Empire, which the classicist Dylan Rogers attributes to the preexisting water cults and greater number of natural springs in regions such as France or Germany. The Romans often established new spa sites at natural springs in conquered territories, many of which still bore connections to local deities. There is evidence suggesting that certain sources of water remained prominent attractions into the 5th-century CE: The poet Rutilius Claudius Namatianus describes his visit to the ("Spring of the Bull"), a spring located near Civitavecchia.Rutilius Claudius Namatianus. De Reditu Suo. 249-254.

In addition to natural sources of water, religious sites in Latium often included infrastructure related to water, such as wells, drainage canals, or cisterns. For instance, alongside two cisterns, excavators have unearthed—by a set of Republican temples in Ostia—remains of a structure that likely once functioned as a well designed to facilitate access to the nearby spring of drinkable water. Another well, which also provided access to spring water, has been uncovered at Fosso dell'Incastro. This structure was probably built around the 3rd-century BCE, yet it likely remained significant to the local populace for the ensuing decades, as they seemingly proactively sought to pits functionality. Later in the 3rd century BCE, there was an effort to pave over the piazza and construct two new altars in the same area, which partially buried the well. Nevertheless, a new conical ring was attached to the structure, which allowed for the continued usage of the site.

According to John Scheid, a scholar of Roman religion, the proximity of water sources to sacred spaces provided suppliants with a convenient means by which they may perform the ablutions required in ritual worship. In Lavinium, multiple canals directed the flow of water towards the nearby sanctuary site. One such canal replaced an earlier stream and may have served primarily to drain water from the area, perhaps akin to a . The sanctuary of Fosso dell'Incastro at Ardea and the temples within the Sant'Omobono Area each utilized cisterns—both dated to the 4th century BCE—which potentially supplied any water-related needs for cult activity. Wells in particular often appear near the altars of a temple, perhaps as they were necessary to provide water for sacrifices. There is evidence of certain sacrificial rites involving water: One ancient inscription dedicated to Silvanus during the reign of Emperor Domitian () mentions "water used for the purpose of the sacrifices." If the divine recipient of a sacrifice was an aquatic god, then the meat of the deceased animal could be deposited in water.

According to Vitruvius, a 1st-century BCE Roman architect, temples and shrines—particularly those of healing deities such as Asclepius or Salus—were often intentionally placed in the most "healthful" ("") places, which were usually defined by the presence of a spring. Vitruvius further claims that when sick individuals receive treatments from these "healthful springs of water" (""), they recover more quickly.Vitruvius. De Architectura. 1.2.7. Festus, a 2nd-century CE Roman grammarian, similarly purports that the Temple of Asclepius was established upon the Tiber Island due to the ability of water to heal illnesses.Festus. De Verborum Significatione. P. 110. M. More specifically, according to the classicist Gil Renberg, the Tiber Island was itself removed from the general pollution and open sewers of the city of Rome, perhaps contributing to its classification as a uniquely salubrious area.

In the eastern half of the empire, it was more common to construct monuments related to water, such as the fountain at Eleusis. Beyond their association with water, large-scale structures such as baths or fountains—as a consequence of their inherent opulence—likely also served as public spectacles that helped accentuate the prestige of the individuals involved with their construction and maintenance. Private civilians often provided financial support for these structures, in some cases receiving explicit commemoration of their contributions to these establishments. In the , a sacred pool in Roman Britain, one inscription termed the "Façade of the Four Seasons" documents the financial investment of an individual named Claudius Ligur, who had funded repairments and a repainting of the local sanctuary.

Deities There were several Roman deities associated with water, including Mefitis, Cloacina, and Magna Mater, the latter two of which were also connected to ritual purification. According to the 1st-century CE Roman naturalist Pliny the Elder, the name of Cloacina was etymologically related to the verb ("to cleans").Pliny the Elder. Natural History. 15.119. Pliny further writes that, following the rape of the Sabine women, the Romans and Sabines purified themselves with myrtle sprigs at a site later occupied by statues of Venus Cloacina.Pliny the Elder. Naturalis Historia. 15. 36. Ovid writes that a grey-haired priest in purple robes washed ("") the "mistress" (""), who was presumably Magna Mater, and her sacred items.Ovid. Fasti. IV. 339-340. Sacred springs often acquired associations with nymphs or other deities, such as Egeria, Juturna, or the Camenae. Sometimes, thermal baths were named after divinities, such as the or , which were named after Neptune and Apollo respectively. Other gods emerged as the personifications of large rivers, such as the god , who represented the Danube, and the god , who embodied the Rhine. Archaeological evidence indicates that Roman soldiers sometimes provided votive offerings to water deities or tossed such dedications into sacred springs. For instance, excavators have unearthed a miniature ballista that was deposited—likely by a soldier—in a pool located within Bath.

During the Imperial period, Roman baths often included statues of deities, of whom the most common—in Italy, North Africa, and Asia Minor—were Asclepius and Hygeia, which may reflect a belief in the healing capabilities of the waters. There is evidence of the importance of water to the cult of Asclepius in the provinces of Dacia and Pannonia Inferior. Near Aquincum in Pannonia, altars dedicated to Asclepius and Hygeia were devoted near a group of sacred springs that also provided the source for the aqueduct. Nearby one such spring, there was a large building that was supplied with water and possibly served as a hospital for the diseased. Numerous votive altars dedicated varying to gods such as Asclepius, Hygeia, and Telesphorus were uncovered near the legionary fort by Aquincum, perhaps implying the existence of a sanctuary to Asclepius attached to the of the encampment. In Dacia, one inscription uncovered near Mehadia records a dedication to Asclepius and Hygeia, which was made supposedly in return for the healing an individual named Iuno Cyrilla via the "divine power of these waters." Archaeological evidence for the role of water in the worship of Asclepius is more limited regarding the northern territories of the Empire, such as Noricum, Brittania, or Germania. In Roman Gaul, however, votive altars honoring Asclepius that were discovered near springs, attesting the significance of water within the cult of the deity.

Symbolism of water

Purity Water was perhaps viewed as pure, with the 1st-century CE author Pliny the Younger writing that the source of the Clitunno river was "clear and vitreous" ("").Pliny the Younger. Letters. 8.8.2. Similarly, Ovid, a 1st-century BCE Roman poet, writes that Claudia Quinta sprinkled ("") pure water from the river ("") thrice upon her head.Ovid. Fasti. IV. 313-315. In Roman literature, the verb , which meant "to wash," also often described cleansing ceremonies. The word only appears three times within the entirety of the Aeneid, and in each of those circumstances it applied to a purificatory rite. For instance, Virgil writes that the character of Turnus traveled through the Tiber River, thereby cleaning ("") himself of "slaughter" ("").Virgil. Aeneid. VI. 818. In another section of the Aeneid, the character Anna approaches her dying sister, Dido, and offers to wash ("") her wounds with water, which perhaps connects to a Greco-Roman practice of ritualistically bathing the deceased.Virgil. Aeneid. IV. 684. The final appearance of the verb surfaces within a passage wherein Virgil states that Aeneas considered it sinful ("") to touch his household gods, the Penates, before he had cleaned ("") his hands of blood using "running water" ("").Virgil. Aeneid. II. 717.