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Title 40: Protection of Environment

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PART 143—NATIONAL SECONDARY DRINKING WATER REGULATIONS 

Section Contents

§ 143.1 Purpose.

§ 143.2 Definitions.

§ 143.3 Secondary maximum contaminant levels.

§ 143.4 Monitoring.

Authority: 42 U.S.C. 300f et seq. 

Source: 44 FR 42198, July 19, 1979, unless otherwise noted. 

§ 143.1 Purpose. 

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This part establishes National Secondary Drinking Water Regulations pursuant to section 1412 of the 

Safe Drinking Water Act, as amended (42 U.S.C. 300g–1). These regulations control contaminants in 

drinking water that primarily affect the aesthetic qualities relating to the public acceptance of drinking 

water. At considerably higher concentrations of these contaminants, health implications may also exist 

as well as aesthetic degradation. The regulations are not Federally enforceable but are intended as 

guidelines for the States. 

§ 143.2 Definitions. 

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(a) Act means the Safe Drinking Water Act as amended (42 U.S.C. 300f et seq.). 

(b) Contaminant means any physical, chemical, biological, or radiological substance or matter in water. 

(c) Public water system means a system for the provision to the public of piped water for human 

consumption, if such a system has at least fifteen service connections or regularly serves an average of 

at least twenty-five individuals daily at least 60 days out of the year. Such term includes (1) any 

collection, treatment, storage, and distribution facilities under control of the operator of such system and 

used primarily in connection with such system, and (2) any collection or pretreatment storage facilities 

not under such control which are used primarily in connection with such system. A public water system 

is either a “community water system” or a “non-community water system.” 

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(d) State means the agency of the State or Tribal government which has jurisdiction over public water 

systems. During any period when a State does not have responsibi1ity pursuant to section 1443 of the 

Act, the term “State” means the Regional Administrator, U.S. Environmental Protection Agency. 

(e) Supplier of water means any person who owns or operates a public water system. 

(f) Secondary maximum contaminant levels means SMCLs which apply to public water systems and 

which, in the judgement of the Administrator, are requisite to protect the public welfare. The SMCL 

means the maximum permissible level of a contaminant in water which is delivered to the free flowing 

outlet of the ultimate user of public water system. Contamimants added to the water under 

circumstances controlled by the user, except those resulting from corrosion of piping and plumbing 

caused by water quality, are excluded from this definition. 

[44 FR 42198, July 19, 1979, as amended at 53 FR 37412, Sept. 26, 1988] 

§ 143.3 Secondary maximum contaminant levels. 

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The secondary maximum contaminant levels for public water systems are as follows: 

These levels represent reasonable goals for drinking water quality. The States may establish higher or 

lower levels which may be appropriate dependent upon local conditions such as unavailability of 

alternate source waters or other compelling factors, provided that public health and welfare are not 

adversely affected. 

[44 FR 42198, July 19, 1979, as amended at 51 FR 11412, Apr. 2, 1986; 56 FR 3597, Jan. 30, 1991] 

§ 143.4 Monitoring. 

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(a) It is recommended that the parameters in these regulations should be monitored at intervals no less 

frequent than the monitoring performed for inorganic chemical contaminants listed in the National Interim 

Primary Drinking Water Regulations as applicable to community water systems. More frequent 

Contaminant Level

Aluminum 0.05 to 0.2 mg/l.

Chloride 250 mg/l.

Color 15 color units.

Copper 1.0 mg/l.

Corrosivity Non-corrosive.

Fluoride 2.0 mg/l.

Foaming agents 0.5 mg/l.

Iron 0.3 mg/l.

Manganese 0.05 mg/l.

Odor 3 threshold odor number.

pH 6.5–8.5.

Silver 0.1 mg/l.

Sulfate 250 mg/l.

Total dissolved solids (TDS) 500 mg/l.

Zinc 5 mg/l.

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monitoring would be appropriate for specific parameters such as pH, color, odor or others under certain 

circumstances as directed by the State. 

(b) Measurement of pH, copper and fluoride to determine compliance under §143.3 may be conducted 

with one of the methods in §141.23(k)(1). Analyses of aluminum, chloride, foaming agents, iron, 

manganese, odor, silver, sulfate, total dissolved solids (TDS) and zinc to determine compliance under 

§143.3 may be conducted with the methods in the following table or alternative methods listed in 

appendix A to subpart C of part 141. Criteria for analyzing aluminum, copper, iron, manganese, silver 

and zinc samples with digestion or directly without digestion, and other analytical test procedures are 

contained in Technical Notes on Drinking Water Methods, EPA–600/R–94–173, October 1994. This 

document is available from the National Service Center for Environmental Publications (NSCEP), P.O. 

Box 42419, Cincinnati, OH 45242–0419 or http://www.epa.gov/nscep/ . 

Contaminant EPA ASTM3

SM418th 

and 19th 

ed.

SM420th 

ed. SM7Online Other

1. Aluminum 200.72 3120 B 3120 B 3120 B–99

 200.82 3113 B 3113 B–99

 200.92 3111 D 3111 D–99

2. Chloride 300.01, 

300.16

D4327–97, 

03

4110 B 4110 B 4110 B–00

 4500–Cl–

D

4500–

Cl–D

4500–Cl–

D–97

 D512–89 

(Reapproved 

1999) B

4500–Cl–

B

4500–

Cl–B

4500–Cl–

B–97

 D6508, 

Rev. 28

3. Color 2120 B 2120 B 2120 B–01

4. Foaming 

Agents

5540 C 5540 C 5540 C–00

5. Iron 200.72 3120 B 3120 B 3120 B–99

 200.92 3111 B 3111 B–99

 3113 B 3113 B–99

6. 

Manganese

200.72 3120 B 3120 B 3120 B–99

 200.82 3111 B 3111 B–99

 200.92 3113 B 3113 B–99

7. Odor 2150 B 2150 B 2150 B–97

8. Silver 200.72 3120 B 3120 B 3120 B–99. I–

3720–

855

 200.82 3111 B 3111 B–99

 200.92 3113 B 3113 B–99

9. Sulfate 300.01, 

300.16

D4327–97, 

03

4110 B 4110 B 4110 B–00

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The procedures shall be done in accordance with the documents listed below. The incorporation by 

reference of the following documents was approved by the Director of the Federal Register in 

accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies of the documents may be obtained from the 

sources listed below. Information regarding obtaining these documents can be obtained from the Safe 

Drinking Water Hotline at 800–426–4791. Documents may be inspected at EPA's Drinking Water 

Docket, EPA West, 1301 Constitution Avenue, NW., Room 3334, Washington, DC (Telephone: 202–

566–2426); or at the National Archives and Records Administration (NARA). For information on the 

availability of this material at NARA, call 202–741–6030, or go to: 

http://www.archives.gov/federal_register/code_of_federal_regulations/ibr_locations.html. 

1“Methods for the Determination of Inorganic Substances in Environmental Samples,” EPA/600/R–93–

100, August 1993. Available at NTIS, PB94–120821. 

2“Methods for the Determination of Metals in Environmental Samples—Supplement I,” EPA/600/R–94–

111, May 1994. Available at NTIS, PB 95–125472. 

3 Annual Book of ASTM Standards, 1994, 1996, 1999, or 2004, Vols. 11.01 and 11.02, ASTM 

International; any year containing the cited version of the method may be used. Copies may be obtained 

from the ASTM International, 100 Barr Harbor Drive, West Conshohocken, PA 19428. 

4 Standard Methods for the Examination of Water and Wastewater, 18th edition (1992), 19th edition 

(1995), or 20th edition (1998). American Public Health Association, 1015 Fifteenth Street, NW., 

Washington, DC 20005. The cited methods published in any of these three editions may be used, except 

that the versions of 3111 B, 3111 D, and 3113 B in the 20th edition may not be used. 

5Method I–3720–85, Techniques of Water Resources Investigation of the U.S. Geological Survey, Book 

5, Chapter A–1, 3rd ed., 1989. Available from Information Services, U.S. Geological Survey, Federal 

Center, Box 25286, Denver, CO 80225–0425. 

6“Methods for the Determination of Organic and Inorganic Compounds in Drinking Water,” Vol. 1, EPA 

815R–00–014, August 2000. Available at NTIS, PB2000–106981. 

7Standard Methods Online are available at http://www.standardmethods.org. The year in which each 

method was approved by the Standard Methods Committee is designated by the last two digits in the 

method number. The methods listed are the only online versions that may be used. 

8Method D6508, Rev. 2, “Test Method for Determination of Dissolved Inorganic Anions in Aqueous 

Matrices Using Capillary Ion Electrophoresis and Chromate Electrolyte,” available from Waters Corp, 34 

Maple St., Milford, MA, 01757, Telephone: 508/482–2131, Fax: 508/482–3625. 

 375.21 4500–

SO42–F

4500–

SO42–F

 4500–

SO42–C, 

D

4500–

SO42–C, 

D

 D516–90, 02 4500–

SO42–E

4500–

SO42–E

 D6508, 

Rev. 28

10. Total 

Dissolved 

Solids

2540 C 2540 C 2540 C–97

11. Zinc 200.72 3120 B 3120 B 3120 B–99

 200.82 3111 B 3111 B–99

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[44 FR 42198, July 19, 1979, as amended at 53 FR 5147, Feb. 19, 1988; 56 FR 30281, July 1, 1991; 59 

FR 62470, Dec. 5, 1994; 64 FR 67466, Dec. 1, 1999; 67 FR 65252, Oct. 23, 2002; 69 FR 18803, Apr. 9, 

2004; 72 FR 11248, Mar. 12, 2007; 74 FR 30959, June 29, 2009] 

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