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MCLs, DLRs, and PHGs for <br />Regulated Drinking Water Contaminants <br />Updated November 2024 <br />The following tables include California’s maximum contaminant levels (MCLs), detection limits for purposes of reporting (DLRs), <br />public health goals (PHGs) from the Office of Environmental Health Hazard Assessment (OEHHA). For comparison, Federal <br />MCLs and Maximum Contaminant Level Goals (MCLGs) from the U.S. EPA are also displayed. Previous MCLs that are no <br />longer effective are shown in italics. Regulatory citations refer to Title 22 of the California Code of Regulations (22 CCR)and <br />Title 40 of the Code of Federal Regulations (40 CFR). <br />This document refers to several units of measurement commonly used in assessing water quality. Concentrations of <br />substances in drinking water are typically expressed in milligrams per liter (mg/L), micrograms per liter (µg/L), nanograms per <br />liter (ng/L), and picocuries per liter (pCi/L). These units help quantify the presence of various chemicals, metals, or radioactive <br />materials. For reference, 1 mg/L equals 1,000 µg/L, and 1 µg/L equals 1,000 ng/L, providing a clear scale for understanding the <br />quantities discussed. Picocuries per liter (pCi/L) measure radioactive material, where 1 pCi/L represents a trillionth of a curie, a <br />standard unit for radioactivity. <br />Inorganic Chemicals <br />The information in the following table can be found in 22 CCR §64431 (California MCLs),22 CCR §64432 (California DLRs), <br />OEHHA’s website (California PHGs), 40 CFR §141.23 (U.S. EPA MCLs), and 40 CFR §141.51 (U.S. EPA MCLGs). The values <br />in this table are in units of micrograms per liter (µg/L) unless otherwise stated. <br />Inorganic Chemicals <br />California U.S. EPA <br />MCL MCL Effective <br />Date DLR PHG PHG <br />Date MCL MCL Effective <br />Date MCLG <br />Aluminum 1,000 1989-02-25 50 600 2001 ------ <br />Antimony 6 1994-09-08 6 1 2016 6 1994-01-17 6 <br />Arsenic 10 <br />50 <br />2008-11-28 <br />1977 <br />2 0.004 2004 10 <br />50 <br />2006-01-23 <br />1977-06-24 <br />zero <br />Asbestos1 7 1994-09-08 0.2 7 2003 7 1992-07-30 7 <br />1 Asbestos units are in million fibers per liter (MFL); for fibers >10 microns long. <br />9.B. - Page 17 of 27 <br />206