A portable water purifying apparatus, including a shell and a hollow, elongated chamber. The apparatus includes a first opening that feeds into this chamber, through which the user draws contaminated water into the chamber, and a second opening for removing purified water from the chamber. Purification of the contaminated water drawn into the apparatus is effected by water purification media, which may include an ultrafiltration membrane; a halogenated resin; and granulated, activated carbon. The apparatus may also include one or more cleanable, removable, replaceable cartridges for containing the water purification media.