According to one embodiment of the present invention, a water purifier can comprise: a filter unit for generating purified water by filtering influent water; a TDS measurement unit provided on the front end of the filter unit so as to measure the TDS of water flowing into the filter unit; a first flow rate measurement unit provided on the front end of the filter unit so as to measure the flow rate of the water flowing into the filter unit; a second flow rate measurement unit provided on the rear end of the filter unit so as to measure the flow rate of the purified water discharged from the filter unit; a concentrated water flow rate adjustment valve for adjusting the flow rate of concentrated water discharged from the filter unit; and a control unit for controlling an opening degree of the concentrated water flow rate adjustment valve on the basis of a measurement value received from at least one of the TDS measurement unit, the first flow rate measurement unit, and the second flow rate measurement unit.