Passage 5.11.11
ἐν Ἐπιδαύρῳ δὲ ἐρομένου μου καθʼ ἥντινα αἰτίαν οὔτε ὕδωρ τῷ Ἀσκληπιῷ σφισιν οὔτε ἔλαιόν ἐστιν ἐγχεόμενον, ἐδίδασκόν με οἱ περὶ τὸ ἱερὸν ὡς καὶ τὸ ἄγαλμα τοῦ θεοῦ καὶ ὁ θρόνος ἐπὶ φρέατι εἴη πεποιημένα.
When I was in Epidaurus, asking for what reason neither water nor olive oil was poured as an offering to their Asclepius, the attendants of the sanctuary informed me that both the statue of the god and the throne had been constructed over a well.