The slow but steady First Need uses a three-stage matrix to draw out and starve viruses. Forcing water through the unit takes time and elbow grease on the pump handle, but the end product is virus-free and ready to quaff, with no need for additional chemical treatment. And because the purifier screws directly onto a Nalgene bottle or filter-compatible reservoir, it’s superhygienic; there’s no chance for a dirty intake hose to touch what you drink.