PURPOSE: To collect water from polluted water, by application of high voltage electromagnetic discharge to highly humid air just passed an aeration bath so as to transform stem into crystalline drops of water and then circulating the resulting low humid dried air to the aeration bath.

CONSTITUTION: By operating a ventilator 2, air is fed to polluted water from a bubble outlet 4 in a bath 1, becomes a highly humid air which is led to an electric conductive material-made part 6 through a ventilating pipe 3, and here a high voltage electromagnetic discharge is applied on the air by a high voltage pressuring apparatus 5 so as to transform steam in the air into crystalline drops of water and take out the drops of water from a liquid outlet 8. Meanwhile the resulting dried air is circulated to the bath 1 through the ventilating pipe 3.