Water treatment method, water treatment systems and water treatment apparatus

Water treatment method according to the embodiment is a water treatment method using a working medium containing the target liquid and draw liquid containing water. Draw solution is hypertonic liquid causing osmotic pressure difference between the water. The method (1) in osmotic pressure generator partitioned by osmosis, by osmotic pressure difference occurring between the target solution and the draw solution, to generate a flux of a mixture of water and a draw solution, ( 2) sending the flux of the mixed liquid to the vaporizing separation unit, (3) by a pressure difference separating the water and draw liquid, and (4) said reuse draw liquid separated in the vaporization separation unit ,including.