The ultraviolet rays kill micro organism, parasites, and viruses. These filters are essentially useless at filtering mineral contaminants, so it’s encouraged to pair this system with a reverse osmosis system. A second option is the pH Replenish pitcher by Invigorated Water (the same company that makes the pH Hydrate bottle): https://daltonvenxe.bloggactivo.com/19812108/glass-water-pitcher-with-filter-an-overview