The rate-limiting step appears to be the barrier presented to the water at the entry and exit of the pore. Similarly, the transport of water through arrays of CNTs ranging in diameter from 0.6 to 1.1 nm was investigated by Corry. He found that ions face a large energy barrier and do not enter 0.68- and 0.8-nm-diameter CNTs. However, as the diameter increases above 0.95 nm, ions can pass through. In contrast, water molecules conduct through all NTs studied, with the conductance increasing with increasing diameter. Similar to Kalra et al, the conduction was independent of NT length. This work suggests that 0.95-nm-diameter CNTs could obtain 95% salt rejection with a water flow rate much faster than existing semipermeable membranes used in desalination.