This study investigates the use of carbon nanotube (CNT) membranes for efficient water desalination through reverse osmosis. Using molecular dynamics simulations, the transport of water and ions through CNTs with diameters ranging from 6 to 11 Å is analyzed under hydrostatic pressure and equilibrium conditions. The results show that ions face a significant energy barrier and cannot pass through narrower CNTs such as (5,5) and (6,6), while water, due to its ability to form stable hydrogen bonds, can pass through all CNTs at high rates. The study determines that the size and uniformity of CNTs required for effective salt rejection are critical for desalination. The research demonstrates that CNT membranes can achieve high desalination efficiency at flow rates far exceeding existing membranes. The study also highlights the importance of pore size and uniformity in achieving desired salt rejection. It is found that the (7,7) and (8,8) CNTs allow for efficient water transport and ion rejection, while the narrower (5,5) and (6,6) CNTs have lower efficiency. The results suggest that CNT membranes could be used for desalination with high efficiency, potentially reducing the energy costs associated with current desalination technologies. The study also compares the performance of CNT membranes with existing reverse osmosis membranes, showing that CNT membranes could offer significant improvements in efficiency and flow rates. The findings have implications for both desalination and understanding biological water and ion channels.This study investigates the use of carbon nanotube (CNT) membranes for efficient water desalination through reverse osmosis. Using molecular dynamics simulations, the transport of water and ions through CNTs with diameters ranging from 6 to 11 Å is analyzed under hydrostatic pressure and equilibrium conditions. The results show that ions face a significant energy barrier and cannot pass through narrower CNTs such as (5,5) and (6,6), while water, due to its ability to form stable hydrogen bonds, can pass through all CNTs at high rates. The study determines that the size and uniformity of CNTs required for effective salt rejection are critical for desalination. The research demonstrates that CNT membranes can achieve high desalination efficiency at flow rates far exceeding existing membranes. The study also highlights the importance of pore size and uniformity in achieving desired salt rejection. It is found that the (7,7) and (8,8) CNTs allow for efficient water transport and ion rejection, while the narrower (5,5) and (6,6) CNTs have lower efficiency. The results suggest that CNT membranes could be used for desalination with high efficiency, potentially reducing the energy costs associated with current desalination technologies. The study also compares the performance of CNT membranes with existing reverse osmosis membranes, showing that CNT membranes could offer significant improvements in efficiency and flow rates. The findings have implications for both desalination and understanding biological water and ion channels.