The Valens Aqueduct bridge received considerably less water after the Avars cut the water supply during the siege of Constantinople in 626. Especially the long Thrace-line seemed to have been out of function.

Theophanes (9th century) points to this siege as the cause for the defect of ‘Valentinian’s aqueduct’, by which he means the Valens Waterway and the Valens aqueduct bridge.