A method for purification of water with a water purifier. The water purifier includes an anode and a cathode as electrodes in such a way that a gap remains between the anode and the cathode. In the method, an electric field is generated between the anode and the cathode, water for purification is conveyed to the gap and an additive enhancing floc formation is introduced to water for purification or to purified water in an amount of less than 50 g and at least 1 g, measured as dry matter, per each cubic metre of water for purification. Floc material manufactured with the method, when water for purification is municipal wastewater. The use of the floc material produced in this way as a soil conditioner or for manufacturing a soil conditioner.