water purification proceeds by reverse osmosis plant using a such a process.

The present invention relates to an energy self-sufficient process water purification and an installation implementing such a method, said apparatus comprising (a) a production module thermodynamic energy from a working fluid (111) and comprising (i) at least two transfer cylinders (101, 102), (ii) an evaporator (105), (iii) a heat source (108) connected to the evaporator (105), (iv) a condenser (106 ), (v) a reservoir (109), (vi) a cold source (110) connected to the condenser (106), (vii) conducting means of the working fluid (111), (viii) control means of the flow of the working fluid (111), (b) a water purification unit to be processed (107), and (c) an energy recovery module comprising (i) a first hydraulic circuit adapted to pressurize the fluid work and (ii) a second hydraulic circuit adapted to at least partially filling the at least two transfer cylinders.