SOUTH DAKOTA Department of
Environment & Natural Resources

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Pierre, SD 57501
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Drinking Water Program

Inorganic Contaminants

Inorganic Contaminants (IOCs) are elements or compounds found in water supplies and may be natural in the geology or caused by activities of man through mining, industry or agriculture.  It is common to have trace amounts of many Inorganic Contaminants in water supplies.  Amounts above the Maximum Contaminant Levels may cause a variety of damaging effects to the liver, kidney, nervous system circulatory system, blood, gastrointestinal system, bones, or skin depending upon the inorganic contaminant and level of exposure.  Some Inorganic Contaminants are more damaging to infants and pregnant women.  Because of some special aspects of the rules for asbestos, fluoride, and nitrates, separate pages can be found for them on this web site.

Do the inorganic contaminant regulations apply to my water system?

Yes, all community and non-transient non-community public water supply systems must monitor for regulated Inorganic Contaminants in their water supply.  At the present there are 15 regulated Inorganic Contaminants (including fluoride, arsenic, and nitrates).

Frequency of sampling

 If your water system exceeds any of the Maximum Contaminant Levels they must:

Inorganic Contaminants With Maximum Contaminant Levels

Antimony 0.006 mg/L
Arsenic 0.01 mg/L
Asbestos 7 million fibers/L
Barium 2 mg/L
Beryllium 0.004 mg/L
Cadmium 0.005 mg/L
Chromium 0.1 mg/L
Cyanide 0.2 mg/L
Fluoride 4 mg/L
Mercury 0.002 mg/L
Nickel 0.1 mg/L
Nitrate 10 mg/L
Nitrite (as N) 1 mg/L
Nitrate & Nitrite (combined) 10 mg/L
Selenium 0.05 mg/L
Thallium 0.002 mg/L

Additional Information

The rules for Inorganic Contaminants are contained in 40 CFR 141.11, 141.23, 141.62.