40 CFR Part 192, Table 1 — Maximum Concentration of Constituents for Groundwater Protection
Verified against eCFR.gov as of June 20, 2026View official text on eCFR.gov ↗
| Constituent concentration 1 | Maximum |
|---|---|
| Arsenic | 0.05 |
| Barium | 1 |
| Cadmium | 0.01 |
| Chromium | 0.05 |
| Lead | 0.05 |
| Mercury | 0.002 |
| Selenium | 0.01 |
| Silver | 0.05 |
| Nitrate (as N) | 10 |
| Molybdenum | 0.1 |
| Combined radium-226 and radium-228 | 5 pCi/liter |
| Combined uranium-234 and uranium-238 2 | 30 pCi/liter |
| Gross alpha-particle activity (excluding radon and uranium) | 15 pCi/liter |
| Endrin (1,2,3,4,10,10-hexachloro-6,7-exposy-1,4,4a,5,6,7,8,8a-octahydro-1,4-endo,endo-5,8-dimethanonaphthalene) | 0.0002 |
| Lindane (1,2,3,4,5,6-hexachlorocyclohexane, gamma insomer) | 0.004 |
| Methoxychlor (1,1,1-trichloro-2,2′-bis(p-methoxyphenylethane)) | 0.1 |
| Toxaphene (C10 H10 Cl6, technical chlorinated camphene, 67-69 percent chlorine) | 0.005 |
| 2,4-D (2,4-dichlorophenoxyacetic acid) | 0.1 |
| 2,4,5-TP Silvex (2,4,5-trichlorophenoxypropionic acid) | 0.01 |
1 Milligrams per liter, unless stated otherwise.
2 Where secular equilibrium obtains, this criterion will be satisfied by a concentration of 0.044 milligrams per liter (0.044 mg/l). For conditions of other than secular equilibrium, a corresponding value may be derived and applied, based on the measured site-specific ratio of the two isotopes of uranium.
[60 FR 2866, Jan. 11, 1995]