U.S. Code of Federal Regulations

Regulations most recently checked for updates: May 28, 2023

§ 143.3 - Secondary maximum contaminant levels.

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

Contaminant Level
Aluminum0.05 to 0.2 mg/l.
Chloride250 mg/l.
Color15 color units.
Copper1.0 mg/l.
Fluoride2.0 mg/l.
Foaming agents0.5 mg/l.
Iron0.3 mg/l.
Manganese0.05 mg/l.
Odor3 threshold odor number.
Silver0.1 mg/l.
Sulfate250 mg/l.
Total dissolved solids (TDS)500 mg/l.
Zinc5 mg/l.
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]