PURE WATER PRODUCING APPARATUS

摘要

PROBLEM TO BE SOLVED: To provide a pure water producing apparatus capable of reducing a risk of scale generation in an electric deionization stack during standby of the apparatus.SOLUTION: There is provided a pure water producing apparatus which comprises: reverse osmosis membrane modules 11 and 12; an electric deionization stack 20 having a desalination chamber 21 and a concentration chamber 22 which are partitioned by alternately arranging a cation exchange membrane and an anion exchange membrane between a pair of electrodes; and a control part 30 which performs a circulation step of returning water W6 passed through the desalination chamber 21 to the upstream side of the reverse osmosis membrane module 11 through a first circulation water line L9 and returning water W7 passed through the concentration chamber 22 to the upstream side of the reverse osmosis membrane module 11 through a second circulation water line L10 for a predetermined time and then shifts from the execution state to the standby state, after the application of power to the electric deionization stack 20 is stopped when shifting from a water intake state where desalted water W6 is supplied to a demand place to a standby state where desalted water W6 is not supplied to a demand place under a state where desalted water cannot be obtained.