The water-bearing figure has roots beyond the Greek tradition. Mesopotamian art includes divine figures with flowing or overflowing water, and the god Ea provides an important background to later interpretations of the water-bearer. Identifying every early image with a fully developed constellation is more difficult than simply matching a vase to a familiar star sign: religious symbols and astronomical systems changed over time. The zodiac also reached Egypt, where monuments such as the Dendera zodiac show the reception of inherited celestial figures. These connections provide a wider setting for Aquarius without making Ea, an Egyptian flood god and the Greek Ganymede the same being. The shared image is water poured from a vessel; the meanings attached to it depend on the culture and the source.

The best-known Greek identification is Ganymede, a youth of the Trojan royal family. In the genealogy preserved by Apollodorus, his father is Tros and his mother Callirrhoe, daughter of the river Scamander. The Iliad describes his exceptional beauty and says that the gods carried him away to serve as cupbearer. Homer does not tell the entire later story of a shepherd seized by Zeus in eagle form. That eagle belongs to other accounts and to the related constellation traditions surrounding Aquila. In these tellings, the movement from the Trojan landscape to Olympus becomes a visible ascent: a mortal youth is lifted into the company of immortals. Associating him with Aquarius gives his new office an enduring image, with the vessel in the heavens recalling the cup he carries for the gods.

On Olympus, Ganymede receives immortality and freedom from ageing. The Homeric Hymn to Aphrodite describes the sorrow of Tros, who does not know what has happened to his son, and the message that eventually brings reassurance. Hermes explains the divine honour granted to Ganymede, and Zeus gives Tros splendid horses as compensation. Ganymede's place as cupbearer also brought him into traditions concerning Hebe, the goddess of youth, and Hera, whose anger appears in some later poetry. The details vary, and the traditions do not agree on one permanent replacement of Hebe by Ganymede. For Aquarius, the central connection is the act of serving a divine drink, not a single agreed history of the Olympian household.

Hyginus preserves more than one answer to the question of the water-bearer's identity. In his Astronomica, many identify the figure as Ganymede, but Hegesianax explains it as Deucalion because a great quantity of water fell from the sky during his time. Deucalion belongs to the Greek flood tradition, surviving with Pyrrha when other people perish. The constellation can therefore recall the deluge rather than a banquet. Hyginus also reports the explanation of Eubulus, who identifies the figure as Cecrops, associated with the use of water in sacrifice before wine was available. Here the vessel points to ritual rather than disaster or service on Olympus. These are alternative interpretations of the same celestial image, not successive adventures of one character. Keeping them separate preserves the variety of ancient star lore.

The astronomical picture centres on the pouring vessel and its stream. Aratus describes the Water-Pourer in relation to the surrounding stars and the Southern Fish, and later constellation imagery continues the connection between the water and the fish beneath it. Fomalhaut marks the mouth of that fish, in Piscis Austrinus rather than Aquarius itself. The boundaries and catalogues of astronomy are distinct from the stories used to remember them. Ganymede's name also travelled beyond the constellation tradition: Simon Marius published it in 1614 for one of Jupiter's four large moons, after those moons had been discovered in 1610. That later naming honours the mythological cupbearer without making the moon part of Aquarius. Across these different settings, a familiar myth supplied a language for naming and imagining the sky.