Water purifying cartridge for empty polyethylene terephthalate or pet bottle

A water purifying cartridge for an empty polyethylene terephthalate or PET bottle comprising:

• a flange member having a diameter substantially the same as an outer shape of a spout of the empty polyethylene terephthalate or PET bottle, the flange member having a thickness portion screwed to fit, in a water-tight manner, to an inner portion of a screw cap, when the screw cap, inherently provided to the empty polyethylene terephthalate or PET bottle, is fitted to a thread portion of the empty polyethylene terephthalate or PET bottle;
• a water charging and discharging mouth portion opened to a substantially central portion of the flange member;
• a hollow neck portion inserted to an inside of the spout of the empty polyethylene terephthalate or PET bottle successive to the flange member, the hollow neck portion having projected portions in a shape of a cross or a shape of a line brought into close contact with an inner diameter of the spout of the empty polyethylene terephthalate or PET bottle by a predetermined length;
• a filter portion arranged right under the hollow neck portion;
• an extractable and contractable adjusting portion filled with at least a first water purifying agent successive to the filter portion;
• a cylindrical portion filled with at least a second water purifying agent successive to the extractable and contractable adjusting portion;
• and
• a water purifying portion which is filled with at least a third water purifying agent, the water purifying portion having an outer periphery provided with meshes or clearances for passing water therethrough.