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Title 40

Displaying title 40, up to date as of 9/17/2021. Title 40 was last amended 9/17/2021.

Title 40

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§ 141.62 Maximum contaminant levels for inorganic contaminants.

(a) [Reserved]

(b) The maximum contaminant levels for inorganic contaminants specified in paragraphs (b) (2)-(6), (b)(10), and (b) (11)-(16) of this section apply to community water systems and non-transient, non-community water systems. The maximum contaminant level specified in paragraph (b)(1) of this section only applies to community water systems. The maximum contaminant levels specified in (b)(7), (b)(8), and (b)(9) of this section apply to community water systems; non-transient, non-community water systems; and transient non-community water systems.

Contaminant MCL (mg/l)
(1) Fluoride 4.0
(2) Asbestos 7 Million Fibers/liter (longer than 10 µm).
(3) Barium 2
(4) Cadmium 0.005
(5) Chromium 0.1
(6) Mercury 0.002
(7) Nitrate 10 (as Nitrogen)
(8) Nitrite 1 (as Nitrogen)
(9) Total Nitrate and Nitrite 10 (as Nitrogen)
(10) Selenium 0.05
(11) Antimony 0.006
(12) Beryllium 0.004
(13) Cyanide (as free Cyanide) 0.2
(14) [Reserved]
(15) Thallium 0.002
(16) Arsenic 0.010

(c) The Administrator, pursuant to section 1412 of the Act, hereby identifies the following as the best technology, treatment technique, or other means available for achieving compliance with the maximum contaminant levels for inorganic contaminants identified in paragraph (b) of this section, except fluoride:

BAT for Inorganic Compounds Listed in Section 141.62(b)

Chemical Name BAT(s)
Antimony 2,7
Arsenic4 1, 2, 5, 6, 7, 9, 125
Asbestos 2,3,8
Barium 5,6,7,9
Beryllium 1,2,5,6,7
Cadmium 2,5,6,7
Chromium 2,5,62,7
Cyanide 5,7,13
Mercury 21,4,61,71
Nickel 5,6,7
Nitrate 5,7,9
Nitrite 5,7
Selenium 1,23,6,7,9
Thallium 1,5

Key to BATS in Table

1 = Activated Alumina

2 = Coagulation/Filtration (not BAT for systems <500 service connections)

3 = Direct and Diatomite 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)

(d) The Administrator, pursuant to section 1412 of the Act, hereby identifies in the following table the affordable technology, treatment technique, or other means available to systems serving 10,000 persons or fewer for achieving compliance with the maximum contaminant level for arsenic:

Small System Compliance Technologies (SSCTs)1 for Arsenic2

Small system compliance technology Affordable for listed small system categories3
Activated Alumina (centralized) All size categories.
Activated Alumina (Point-of-Use)4 All size categories.
Coagulation/Filtration5 501-3,300, 3,301-10,000.
Coagulation-assisted Microfiltration 501-3,300, 3,301-10,000.
Electrodialysis reversal6 501-3,300, 3,301-10,000.
Enhanced coagulation/filtration All size categories
Enhanced lime softening (pH>10.5) All size categories.
Ion Exchange All size categories.
Lime Softening5 501-3,300, 3,301-10,000.
Oxidation/Filtration7 All size categories.
Reverse Osmosis (centralized)6 501-3,300, 3,301-10,000.
Reverse Osmosis (Point-of-Use)4 All size categories.

[56 FR 3594, Jan. 30, 1991, as amended at 56 FR 30280, July 1, 1991; 57 FR 31847, July 17, 1992; 59 FR 34325, July 1, 1994; 60 FR 33932, June 29, 1995; 66 FR 7063, Jan. 22, 2001; 68 FR 14506, Mar. 25, 2003; 69 FR 38855, June 29, 2004]