AquaTru Classic filters tap water based on reverse osmosis. Fill the rear tank with tap water and the system does the rest. AquaTru Classic uses a multi-stage purification process, including a sediment filter, a pre-carbon filter, a reverse osmosis membrane and a post-carbon filter. Together, these filters remove contaminants from water such as chlorine, lead, arsenic, fluoride and more. The result is pure, clean and delicious water. The filtering process takes 12-15 minutes. You can also use the purified water for hot drinks or for cooking.