The paintings preserved in the Dura-Europos baptistery have often been interpreted through supposed correspondences with biblical texts. However, the analysis of this art often fails to appreciate the instability of Christian textual forms in the third century, not to mention the popularity in Syria of the Diatessaron and (what would later be called) apocryphal texts. My paper argues that one painting from the baptistery can be fruitfully re-interpreted in connection with Christian apocrypha, east Syrian baptismal theology, and unheralded artistic comparanda. The woman bent over a well is not marked specifically as the Samaritan Woman from the Gospel of John. There are women at wells all over the biblical landscape, an intertextual play already enacted by the Gospel of John itself. But more importantly, Christian apocrypha narrate a tradition of the Annunciation to Mary at a well. This interpretation helps to explain a few anomalous features of the painting. It is also corroborated by later iconographic traditions and liturgical ideas that were prominent in Syrian Christianity. The paper concludes by describing the polysemic functions of this painting in the ritual space.