In Hellenistic and Roman Arabia and Egypt, a hydreuma (plural hydreumata) was an enclosed (and often fortified) "watering station" (Classical Latin hydreuma  from Ancient Greek ὕδρευμα from ὕδωρ, water ) at wadis in dry regions. A hydreuma was a manned and fortified watering hole or way station along a caravan route, providing a man-made oasis.
In the 1st century CE, Pliny's Natural History described the current Roman sea-route to India, which had recently been established. The Via Hadriana, the route that linked the Nile with the Red Sea, was established by hydreumata. The annual caravan from Alexandria sailed up the Nile to Keft (Pliny's Coptus).
- "From Keft the journey is made with camels, stations being placed at intervals for the purpose of watering; the first, a stage of 22 miles, is called Hydreuma; the second is in the mountains, a day's journey on;  the third at a second place named Hydreuma, 85 miles from Keft; the next is in the mountains; next we come to Apollo's Hydreuma, 184 miles from Keft; again a station in the mountains ; then we get to New Hydreuma, 230 miles from Keft. There is also another old Hydreuma known by the name of Trogodyticum, where a guard is stationed on outpost duty at a caravanserai accommodating two thousand travellers; it is seven miles from New Hydreuma. Then comes the town of Berenice where there is a harbour on the Red Sea, 257 miles from Keft."
The site of the "Hydreuma of Apollo", Apollos Hydreuma, mentioned by Pliny has yielded papyri in modern times. The hydreumata of Abu Qreiya and of Samut have been surveyed but not excavated. Abu Qreiya, one of these watering places, consists today of a concrete well in the wadi, drilled at the beginning of the 20th century; Aby Qreiya has been surveyed but not excavated.
Another route dictated by hydreumata dug into the beds of wadis linked the barren mountain that was the sole source of Roman "imperial porphyry" with the Nile, the Via Porphyritis, the Porphyry Road.
- Along the way are seven hydreumata, or fortified wells, each one a day's march from the next. Outside the fortifications are lines of large stones to which oxen were tethered at night." (Werner 1998).
- Lewis, C.T. & Short, C. (1879). A Latin dictionary founded on Andrews' edition of Freund's Latin dictionary. Oxford: Clarendon Press.
- Liddell, H.G. & Scott, R. (1940). A Greek-English Lexicon. revised and augmented throughout by Sir Henry Stuart Jones. with the assistance of. Roderick McKenzie. Oxford: Clarendon Press.
- "aquationum ratione mansionibus dispositis: prima appellatur hydreuma, secunda in monte diei itinere, tertia in altero hydreumate a copto, deinde in monte; mox ad hydreuma apollinis a copto, rursus in monte; mox ad novum hydreuma a copto" (Pliny xvii.45)
- Ancient History Sourcebook: Pliny: Natural History 6.96-111. (On India)
- Abu Qreiya
- Saudi Aramco World Louis Werner, "Via Porphyrites" November/December 1998