As much water ran through as the aperture could accommodate.
Advanced English Dictionary
+noun 1 (formal) a small opening in sth: The soldier fired the rifle through a narrow aperture in a pile of sandbags. 2 (technical) an opening that allows light to reach a LENS, especially in cameras: For flash photography, set the aperture at f.5.6. + Open up the lens aperture to maximize the brightness of the shot. + Binoculars of this aperture are very expensive.
Random quote: If you smile when no one else is around, you really mean it.: Andy Rooney