The present disclosure relates to nanochannel plates for use in reverse osmosis systems and methods of their manufacture. An example nanochannel plate includes a first surface and an opposing second surface. The first surface and the second surface are parallel to a major flat of the nanochannel plate. The nanochannel plate also includes a plurality of channels. At least one channel includes a carbon nanotube having a first end opening proximate to the first surface and a second end opening proximate to the second surface. Optionally, a core portion of the carbon nanotube could be configured to transport water from the first surface to the second surface or vice versa. Optionally, the core portion of the carbon nanotube has a core diameter of less than or equal to 0.7 nanometers.