Abstract: A water purifying cartridge, attached to an empty polyethylene terephthalate or PET bottle integrally formed with a seat member, including: a flange member having substantially the same diameter as an outer shape of a spout of the bottle and a thickness portion screwed to water-tightly fit an inner portion of a screw cap of the bottle; a water charging/discharging mouth portion opened to a substantially central portion of the flange member; a hollow neck portion inserted inside of the spout of the bottle adjacent to the flange member and having projected portions; a filter portion under the neck portion; an extractable/contractable adjusting portion adjacent to the filter portion; a cylindrical portion adjacent to the adjusting portion; and a water purifying portion having an outer periphery with clearances for passing water therethrough. The adjusting portion, the cylindrical portion and the water purifying portion all containing water purifying agents.

Abstract: To provide a water purifying cartridge capable of simply attaching to an empty pet bottle which is on sale and is distributed by a large number and even to an empty bottle of a type integrally formed with a seat member without cutting the seat member, the water purifying cartridge includes a flange member having a diameter substantially the same as an outer shape of a spout of an empty bottle and having a thickness portion screwed to fit, in water tight, to an inner portion of a screw cap when the screw cap inherently provided to the empty pet bottle is fitted to a thread portion of the empty 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 inside of the spout of the pet bottle successive to the flange member and 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 by a predetermined length, a filter portion arranged right un