Water purifier

A water purifier comprising:

• an attachment main body that is attached to a bibcock of a water line and includes an inflow port, at least one outflow port, an inflow passage into which raw water from said inflow port flows, and first and second outflow passages through each of which water flows toward one of said at least one outflow port;
• and
• a water purification main body that is attached rotatably to said attachment main body and includes a first flow passage, a second flow passage, and a third flow passage, a first filter member disposed between said first flow passage and said second flow passage and a second filter member disposed between said second flow passage and said third flow passage;
• wherein
• when said attachment main body and said water purification main body are in a rotation position corresponding to a water purification mode, said first flow passage and said second flow passage communicate with said inflow passage and said first outflow passage, respectively, whereby water flows in a direction of said first flow passage, said first filter member, and said second flow passage such that purified water flows out through one of said at least one outflow port, and when said attachment main body and said water purification main body are in a rotation position corresponding to a back washing mode, said third flow passage and said first flow passage communicate with said inflow passage and said second outflow passage, respectively, whereby water flows in a direction of said third flow passage, said second filter member, said second flow passage, said first filter member, and said first flow passage such that water used for back washing flows out through one of said at least one outflow port.