Water treatment apparatus and sterilizing and cleansing method thereof

A water treatment apparatus comprising:

• a filter unit purifying raw water input into the water treatment apparatus, the filter unit comprising two or more filters configured to filter the raw water, wherein the two or more filters are connected to each other by a plurality of flow paths;
• a flow path changing valve comprising a water inlet, a first water outlet and a second water outlet, with the water inlet being fixedly connected to an output of only a portion of the two or more filters, wherein the flow path changing valve is configured to connect the water inlet to one of the first water outlet and the second water outlet;
• a storage tank connected to the filter unit and configured to store purified water which has been filtered by all of the two or more filters of the filter unit, when the water treatment apparatus is in a water purification mode;
• a sterilization water line configured to connect an output of fewer than all of the two or more filters to the storage tank when the water treatment apparatus is in a water sterilization mode;
• an electrolytic sterilizer installed in the sterilization water line, the electrolytic sterilizer configured to generate sterilization water including a sterilizing material by electrolyzing the raw water filtered by fewer than all of the two or more filters of the filter unit in the sterilization mode;
• a drain unit connected to the storage tank, the drain unit configured to discharge water accommodated in the storage tank;
• and
• a control unit configured to control the flow path changing valve,
• wherein, when in the water purification mode, the control unit controls the flow path changing valve to output purified water filtered by all of the two or more filters of the filter unit to the storage tank, and, when in the sterilization mode, the control unit controls the flow path changing valve to output the sterilization water filtered through fewer than all of the two or more filters of the filter unit to the storage tank,
• wherein the sterilization water passes through the electrolytic sterilizer, and the sterilization water is supplied to the storage tank and is discharged from the storage tank through the drain unit or a water extraction cock connected to the storage tank,
• wherein the sterilization water line is configured as a flow path separate from a purified water line connecting a final filter of the two or more filters of the filter unit to the storage tank,
• wherein the sterilization water line is without a filter at a rear stage of the electrolytic sterilizer so that the sterilization water is fed to the storage tank without passing through any filters of the filter unit when in the sterilization mode,
• wherein, in the sterilization mode, the control unit is configured to discharge the sterilization water supplied in the storage tank through the water extraction cock,
• wherein the water extraction cock is connected to a drain line of the drain unit through a connection member, and
• wherein the connection member comprises a first connection cap detachable with respect to a discharging end of the water extraction cock, a second connection cap detachable with respect to the drain unit, and a connection hose connecting the first and second connection caps.