Water permeation across a single-walled carbon nanotube has been studied in the presence of static electric fields (SEFs) with different directions under hydrostatic pressures. With the angle between the SEF direction and tube axis increasing from 0 degrees to 90 degrees, the water flux decreases gradually until almost vanishes, and the maximum value at 0 degrees is approximately four times the case without SEFs. The phenomenon is attributed to the alignment of the polar water molecules along the SEF direction. We also show that water permeation properties are dependent on the field strength due mainly to thermal fluctuations of water molecules. (C) 2015 Elsevier B.V. All rights reserved.