Rule 3745-81-12. Maximum contaminant levels and best available technologies for organic contaminants

119.03 (A) The director may determine that a public water system shall apply the following best available technology (BAT), for achieving compliance with the maximum contaminant levels (MCLs) for organic disinfection byproducts identified in this table: Contaminant MCL (mg/L) BAT Total trihalomethanes 0.080 Enhanced coagulation or enhanced softening plus GAC10; or nanofiltration with a molecular weight of less than or equal to 1000 Daltons; or GAC20 Haloacetic acids(five) 0.060 Enhanced coagulation or enhanced softening plus GAC10; or nanofiltration with a molecular weight of less than or equal to 1000 Daltons; or GAC20 (B) The director may determine that a public water system shall apply the following best technology, treatment techniques or other means available for achieving compliance with the MCLs for TTHM and HAA5 identified in this rule for consecutive systems and applies only to the disinfected water that consecutive systems buy or otherwise receive: Contaminant MCL(mg/L) BAT Total trihalomethanes 0.080 Systems serving greater than or equal to 10,000: Improved distribution system and storage tank management to reduce residence time, plus the use of chloramines for disinfectant residual maintenance. Systems serving less than 10,000: Improved distribution system and storage tank management to reduce residence time. Haloacetic acids(five) 0.060 Systems serving greater than or equal to 10,000: Improved distribution system and storage tank management to reduce residence time, plus the use of chloramines for disinfectant residual maintenance. Systems serving less than 10,000: Improved distribution system and storage tank management to reduce residence time. (C) The following maximum contaminant levels (MCLs) apply to community public water systems and nontransient noncommunity public water systems

distribution system and storage tank management to reduce residence time, plus the use of chloramines for disinfectant residual maintenance. Systems serving less than 10,000: Improved distribution system and storage tank management to reduce residence time. (C) The following maximum contaminant levels (MCLs) apply to community public water systems and nontransient noncommunity public water systems. The associated BATs, designated as GAC for granular activated carbon and PTA for packed-tower aeration, identify the best technology, treatment techniques or other means available for achieving compliance with the stated MCLs. The director may determine that a public water system shall apply best available technology in order to reduce the level of a contaminant to below the contaminant's MCL. Contaminant CAS number MCL (mg/L) BAT Vinyl chloride 75-01-4 0.002 PTA Benzene 71-43-2 0.005 GAC PTA Carbon tetrachloride 56-23-5 0.005 GACPTA p-Dichlorobenzene 106-46-7 0.075 GAC PTA 1,2-Dichloroethane 107-06-2 0.005 GACPTA 1,1-Dichloroethylene 75-35-4 0.007 GAC PTA Trichloroethylene 79-01-6 0.005 GAC PTA 1,1,1-Trichloroethane 71-55-6 0.2 GACPTA o-Dichlorobenzene 95-50-1 0.6 GAC PTA cis-1,2-Dichloroethylene 156-59-2 0.07 GACPTA trans-1,2-Dichloroethylene 156-60-5 0.1 GACPTA 1,2-Dichloropropane 78-87-5 0.005 GAC PTA Dichloromethane 75-09-2 0.005 PTA Ethylbenzene 100-41-4 0.7 GAC PTA Monochlorobenzene 108-90-7 0.1 GACPTA Styrene 100-42-5 0.1 GACPTA Tetrachloroethylene 127-18-4 0.005 GAC PTA Toluene 108-88-3 1 GACPTA 1,2,4-Trichlorobenzene 120-82-1 0.07 GAC PTA 1,1,2-Trichloroethane 79-00-5 0.005 GACPTA Xylenes (total) 1330-20-7 10 GACPTA (D) The following maximum contaminant levels apply to community public water systems and nontransient noncommunity water systems. The associated BATs, designated as GAC for granular activated carbon, PTA for packed-tower aeration, and OX for oxidation with chlorine or ozone, identify the best technology, treatment technique or other means available for achieving compliance with the stated MCLs

PTA (D) The following maximum contaminant levels apply to community public water systems and nontransient noncommunity water systems. The associated BATs, designated as GAC for granular activated carbon, PTA for packed-tower aeration, and OX for oxidation with chlorine or ozone, identify the best technology, treatment technique or other means available for achieving compliance with the stated MCLs. The director may determine that a public water system shall apply BAT in order to reduce the level of a contaminant to below the contaminant's MCL. Contaminant CAS number MCL (mg/L) BAT Alachlor 15972-60-8 0.002 GAC Atrazine 1912-24-9 0.003 GAC Benzo[a]pyrene 50-32-8 0.0002 GAC Carbofuran 1563-66-2 0.04 GAC Chlordane 57-74-9 0.002 GAC 2,4-D 94-75-7 0.07 GAC Dalapon 75-99-0 0.2 GAC Dibromochloropropane (DBCP) 96-12-8 0.0002 GACPTA Di(2-ethylhexyl)adipate 103-23-1 0.4 GAC Di(2-ethylhexyl) phthalate 117-81-7 0.006 GAC Dinoseb 88-85-7 0.007 GAC Diquat 85-00-7 0.02 GAC Endothall 145-73-3 0.1 GAC Endrin 72-20-8 0.002 GAC Ethylene dibromide (EDB) 106-93-4 0.00005 GACPTA Glyphosate 1071-53-6 0.7 OX Heptachlor 76-44-8 0.0004 GAC Heptachlor epoxide 1024-57-3 0.0002 GAC Hexachlorobenzene 118-74-1 0.001 GAC Hexachlorocyclopentadiene 77-47-4 0.05 GACPTA Lindane 58-89-9 0.0002 GAC Methoxychlor 72-43-5 0.04 GAC Oxamyl (Vydate) 23135-22-0 0.2 GAC Picloram 1918-02-1 0.5 GAC Polychlorinated biphenyls (PCBs) 1336-36-3 0.0005 GAC Pentachlorophenol 87-86-5 0.001 GAC Simazine 122-34-9 0.004 GAC 2,3,7,8-TCDD (Dioxin) 1745-01-6 3 x10 -8 GAC Toxaphene 8001-35-2 0.003 GAC 2,4,5-TP (Silvex) 93-72-1 0.05 GAC Last updated June 25, 2025 at 6:02 PM Supplemental Information Authorized By: 6109.04 Amplifies: 6109.03 , 6109.04 2/6/2028 4/1/2016