Abstract: Ambient air (2) is canalized and cooled in a free space (4) delimited by a thermally insulated enclosure (1) and a radiating heat exchanger (3) of which the outer face (6) is heat-absorbing and the inner face (5) is heat-radiating. Air is then passed through a curtain of hygroscopic fibres (11) where water vapor condensates into liquid water which is evacuated through a conduit (14) and, once dried, air is heated by flowing at the inside (8) of a radiator (7) recovering thermal energy emitted by the face (5) of the heat exchanger (3) through a transparent thermally insulating volume (12). Dry air is then exhausted through a vent (9) to the atmosphere. Since air circulates naturally, it is possible to recover, autonomously and without any other energy supply, water contained in vapor form in the atmosphere of the implantation site.