The Filterbaby Filter Replacements sits inside your Filterbaby system and needs to be replaced every 90 days. Our filter contains best in class, multi-step filtration that removes contaminants as small as .1 microns. Don't backtrack your progress! We've made it super easy to remember to change your filter. By subscribing, your replacement filter will arrive on your doorstep automatically every 90 days, guaranteeing you fresh, clean water that your skin deserves.