Regulations last checked for updates: Oct 17, 2024

Title 40 - Protection of Environment last revised: Oct 15, 2024
§ 141.50 - Maximum contaminant level goals for organic contaminants.

(a) MCLGs are zero for the following contaminants:

(1) Benzene.

(2) Vinyl chloride.

(3) Carbon tetrachloride.

(4) 1,2-dichloroethane.

(5) Trichloroethylene.

(6) Acrylamide.

(7) Alachlor.

(8) Chlordane.

(9) Dibromochloropropane.

(10) 1,2-Dichloropropane.

(11) Epichlorohydrin.

(12) Ethylene dibromide.

(13) Heptachlor.

(14) Heptachlor epoxide.

(15) Pentachlorophenol.

(16) Polychlorinated biphenyls (PCBs).

(17) Tetrachloroethylene.

(18) Toxaphene.

(19) Benzo[a]pyrene.

(20) Dichloromethane (methylene chloride).

(21) Di(2-ethylhexyl)phthalate.

(22) Hexachlorobenzene.

(23) 2,3,7,8-TCDD (Dioxin).

(24) PFOA.

(25) PFOS.

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

Contaminant MCLG in mg/l
(unless otherwise noted)
(1) 1,1-Dichloroethylene0.007
(2) 1,1,1-Trichloroethane0.20
(3) para-Dichlorobenzene0.075
(4) Aldicarb0.001
(5) Aldicarb sulfoxide0.001
(6) Aldicarb sulfone0.001
(7) Atrazine0.003
(8) Carbofuran0.04
(9) o-Dichlorobenzene0.6
(10) cis-1,2-Dichloroethylene0.07
(11) trans-1,2-Dichloroethylene0.1
(12) 2,4-D0.07
(13) Ethylbenzene0.7
(14) Lindane0.0002
(15) Methoxychlor0.04
(16) Monochlorobenzene0.1
(17) Styrene0.1
(18) Toluene1
(19) 2,4,5-TP0.05
(20) Xylenes (total)10
(21) Dalapon0.2
(22) Di(2-ethylhexyl)adipate.4
(23) Dinoseb.007
(24) Diquat.02
(25) Endothall.1
(26) Endrin.002
(27) Glyphosate.7
(28) Hexachlorocyclopentadiene.05
(29) Oxamyl (Vydate).2
(30) Picloram.5
(31) Simazine.004
(32) 1,2,4-Trichlorobenzene.07
(33) 1,1,2-Trichloroethane.003
(34) Hazard Index PFAS (HFPO-DA, PFBS, PFHxS, and PFNA)1 (unitless). 1
(35) HFPO-DA0.00001.
(36) PFHxS0.00001.
(37) PFNA0.00001.

1 The PFAS Mixture Hazard Index (HI) is the sum of component hazard quotients (HQs), which are calculated by dividing the measured component PFAS concentration in water by the corresponding contaminant's health-based water concentration (HBWC) when expressed in the same units (shown in ng/l). The HBWC for PFHxS is 10 ng/l; the HBWC for HFPO-DA is 10 ng/l; the HBWC for PFNA is 10 ng/l; and the HBWC for PFBS is 2000 ng/l. A PFAS Mixture Hazard Index greater than 1 (unitless) indicates an exceedance of the health protective level and indicates potential human health risk from the PFAS mixture in drinking water.

Hazard Index = ([HFPO-DAwater ng/l]/[10 ng/l]) + ([PFBSwater ng/l]/[2000 ng/l]) + ([PFNAwater ng/l]/[10 ng/l]]) + ([PFHxSwater ng/l]/[10 ng/l]) HBWC = health-based water concentration HQ = hazard quotient ng/l = nanograms per liter PFASwater = the concentration of a specific PFAS in water [50 FR 46901, Nov. 13, 1985, as amended at 52 FR 20674, June 2, 1987; 52 FR 25716, July 8, 1987; 56 FR 3592, Jan. 30, 1991; 56 FR 30280, July 1, 1991; 57 FR 31846, July 17, 1992; 89 FR 32744, April 25, 2024]
§ 141.51 - Maximum contaminant level goals for inorganic contaminants.

(a) [Reserved]

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

Contaminant MCLG (mg/l)
Antimony0.006
Arseniczero 1
Asbestos7 Million fibers/liter (longer than 10 µm).
Barium2
Beryllium.004
Cadmium0.005
Chromium0.1
Copper1.3
Cyanide (as free Cyanide).2
Fluoride4.0
Leadzero
Mercury0.002
Nitrate10 (as Nitrogen).
Nitrite1 (as Nitrogen).
Total Nitrate + Nitrite10 (as Nitrogen).
Selenium0.05
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]
§ 141.52 - Maximum contaminant level goals for microbiological contaminants.

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

Contaminant MCLG
(1) Giardia lambliazero
(2) Viruseszero
(3) Legionellazero
(4) Total coliforms (including fecal)zero
coliforms and Escherichia coli
(5) Cryptosporidiumzero
(6) Escherichia coli (E. coli)zero

(b) The MCLG identified in paragraph (a)(4) of this section is applicable until March 31, 2016. The MCLG identified in paragraph (a)(6) of this section is applicable beginning April 1, 2016.

[78 FR 10347, Feb. 13, 2013]
§ 141.53 - Maximum contaminant level goals for disinfection byproducts.

MCLGs for the following disinfection byproducts are as indicated:

Disinfection byproduct MCLG
(mg/L)
Bromodichloromethanezero
Bromoformzero
Bromatezero
Chlorite0.8
Chloroform0.07
Dibromochloromethane0.06
Dichloroacetic acidzero
Monochloroacetic acid0.07
Trichloroacetic acid0.02
[63 FR 69465, Dec. 16, 1998, as amended at 65 FR 34405, May 30, 2000; 71 FR 478, Jan. 4, 2006]
§ 141.54 - Maximum residual disinfectant level goals for disinfectants.

MRDLGs for disinfectants are as follows:

Disinfectant residual MRDLG(mg/L)
Chlorine4 (as Cl 2).
Chloramines4 (as Cl 2).
Chlorine dioxide0.8 (as ClO2)
[63 FR 69465, Dec. 16, 1998]
§ 141.55 - Maximum contaminant level goals for radionuclides.

MCLGs for radionuclides are as indicated in the following table:

Contaminant MCLG
1. Combined radium-226 and radium-228Zero.
2. Gross alpha particle activity (excluding radon and uranium)Zero.
3. Beta particle and photon radioactivityZero.
4. UraniumZero.
[65 FR 76748, Dec. 7, 2000]
source: 40 FR 59570, Dec. 24, 1975, unless otherwise noted.
cite as: 40 CFR 141.55