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 Code of Federal Regulations (Last Updated: November 8, 2024)
 Title 40 - Protection of Environment
 Chapter I - Environmental Protection Agency
 SubChapter D - Water Programs
 Part 141 - National Primary Drinking Water Regulations
 Subpart F - Maximum Contaminant Level Goals and Maximum Residual Disinfectant Level Goals

  § 141.51 - Maximum contaminant level goals for inorganic contaminants.  

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  • § 141.51 Maximum contaminant level goals for inorganic contaminants.

    (a) [Reserved]

    (b) MCLGs for the following contaminants are as indicated:

    Contaminant MCLG (mg/l)
    Antimony 0.006
    Arsenic zero1
    Asbestos 7 Million fibers/liter (longer than 10 µm).
    Barium 2
    Beryllium .004
    Cadmium 0.005
    Chromium 0.1
    Copper 1.3
    Cyanide (as free Cyanide) .2
    Fluoride 4.0
    Lead zero
    Mercury 0.002
    Nitrate 10 (as Nitrogen).
    Nitrite 1 (as Nitrogen).
    Total Nitrate + Nitrite 10 (as Nitrogen).
    Selenium 0.05
    Thallium .0005

    1 This value for arsenic is effective January 23, 2006. Until then, there is no MCLG.

    [50 FR 47155, Nov. 14, 1985, as amended at 52 FR 20674, June 2, 1987; 56 FR 3593, Jan. 30, 1991; 56 FR 26548, June 7, 1991; 56 FR 30280, July 1, 1991; 57 FR 31846, July 17, 1992; 60 FR 33932, June 29, 1995; 66 FR 7063, Jan. 22, 2001]