Berkey Systems is constructed of highly polished AISI 304 stainless steel. The Black Berkey Purification Element formulation has been tested by State and EPA accredited laboratories to exceed NSF/ANSI Standard 53 The Fluoride and Arsenic Reduction Filters absorb the following unwanted elements found in drinking water: Fluoride: Sodium Fluoride, Sodium Fluorosilicate, Fluorosilicic Acid (aka Hydrofluorosilic Acid) Arsenic: V and pre-oxidized Arsenic III, other residual heavy metal ions.