Rule 3745-81-11. Maximum contaminant levels and best available technologies for inorganic contaminants

119.03 (A) The following maximum contaminant levels (MCLs) for inorganic contaminants apply to all public water systems. Contaminant MCL in milligrams per liter Nitrate (as nitrogen) 10 Nitrite (as nitrogen) 1 Total nitrate and nitrite (as nitrogen) 10 (B) The following MCLs for inorganic contaminants apply to all community and nontransient noncommunity public water systems. Contaminant MCL in milligrams per liter Antimony 0.006 Arsenic 0.010 Asbestos 7 a Barium 2 Beryllium 0.004 Cadmium 0.005 Chromium 0.1 Cyanide (as free cyanide) 0.2 Fluoride 4.0 Mercury 0.002 Selenium 0.05 Thallium 0.002 a. In units of millions of fibers per liter, where only fibers longer than ten micrometers are counted. (C) The following MCL for bromate applies to all community and nontransient noncommunity public water systems that treat their water with ozone. Contaminant MCL in milligrams per liter Bromate 0.010 (D) The following MCL for chlorite applies to all community and nontransient noncommunity public water systems that treat their water with chlorine dioxide. Contaminant MCL in milligrams per liter Chlorite 1.0 (E) The director may require a public water system to apply best available technology in order to reduce the level of a contaminant to below its MCL. The director identifies the following as the best available technologies (BATs) for removal of the following inorganic contaminants from water. Contaminant BATs Antimony 2,7 Arsenic a 1, 2, 5, 6, 7, 9, 12 b Asbestos 2, 3, 8 Barium 5, 6, 7, 9 Beryllium 1, 2, 5, 6, 7 Bromate 14 Cadmium 2, 5, 6, 7 Chlorite 15 Chromium 2, 5, 6 c , Cyanide 5, 7, 13 Mercury 2 d , 4, 6 d , 7 d Nitrate 5, 7, 9 Nitrite 5, 7 Selenium 1, 2 e , 6, 7, 9 Thallium 1, 5 a. BATs for arsenic (V). Pre-oxidation may be required to convert arsenic (III) to arsenic (V) b. To obtain high removals the iron to arsenic ratio must be at least 20:1 c. BAT for chromium (III) only d. BAT only for mercury concentrations of ten micrograms per liter or less e

5, 6 c , Cyanide 5, 7, 13 Mercury 2 d , 4, 6 d , 7 d Nitrate 5, 7, 9 Nitrite 5, 7 Selenium 1, 2 e , 6, 7, 9 Thallium 1, 5 a. BATs for arsenic (V). Pre-oxidation may be required to convert arsenic (III) to arsenic (V) b. To obtain high removals the iron to arsenic ratio must be at least 20:1 c. BAT for chromium (III) only d. BAT only for mercury concentrations of ten micrograms per liter or less e. BAT for selenium (IV) only Key to BATs in table: 1 = Activated alumina 2 = Coagulation/filtration (not BAT for systems 500 service connections) 3 = Direct filtration 4 = Granular activated carbon 5 = Ion exchange 6 = Lime softening (not BAT for systems 500 service connections) 7 = Reverse osmosis 8 = Corrosion control 9 = Electrodialysis 10 = Chlorine 11 = Ultraviolet 12 = Oxidation/filtration 13 = Alkaline chlorination (pH >8.5) 14 = Control of ozone treatment process to reduce production of bromate 15 = Control of treatment processes to reduce disinfectant demand and control of disinfectant treatment processes to reduce disinfectant levels Last updated October 31, 2024 at 8:40 AM Supplemental Information Authorized By: 6109.03 , 6109.04 Amplifies: 6109.04 10/31/2029 12/27/1978, 3/1/1988, 1/1/2002