Water transport across cell membrane, illustration. Water (blue) is shown crossing a cell membrane. Water carried across a semi-permeable membrane by solute molecules is a process known as osmosis. In addition to this, water transport is aided by membrane proteins known as aquaporins that form channels that help water molecules pass in and out of the cell. Unlike ion channels, aquaporins help prevent ions and other dissolved substances carrying electrical charge from entering the cell, as they only allow lone water molecules or certain uncharged solutes to pass through. This helps to maintain the electrochemical potential of the membrane.