The invention relates to a device comprising a container (1) having an upper filling mouth (11), for storing water to be supplied by at least one threat (2) or strand of material that can be impregnated by water by capillarity once the container has been buried. Said container (1) comprises openings (12) at the top thereof, below the level of the filling mouth (11), from which the threads (2) consisting of synthetic fibres emerge together. Said threads have at least one inner section (21) with an end extending inside the container (1), to the bottom thereof, and an outer section (22) which comes into contact with the earth. Once the container (1) is buried up to the level of the upper mouth (11), with the openings (12) below the ground level, the threads (2) carry out a gradual transfer of the water from the inside to the outside of the container (1), by capillarity.
