Method and apparatus for treating water

A water treatment apparatus that decomposes organic substances contained in water to be treated, comprising:

• a hydrogen peroxide source configured to add hydrogen peroxide to a pipe that includes the water to be treated;
• an ultraviolet oxidation device configured to irradiate the water to be treated to which hydrogen peroxide has been added with ultraviolet light;
• and
• a hydrogen peroxide removal device configured to remove hydrogen peroxide contained in outlet water from the ultraviolet oxidation device,
• wherein the hydrogen peroxide removal device comprises:
• an anode and a cathode;
• and
• a hydrogen peroxide removal chamber disposed between the anode and the cathode and packed with a metal catalyst having an ability of decomposing hydrogen peroxide, the hydrogen peroxide removal chamber being partitioned by an anion exchange membrane arranged on a side facing the anode, and
• wherein the removal device is configured so that a DC current can be applied between the anode and the cathode.