U.S. Code of Federal Regulations
Regulations most recently checked for updates: Aug 27, 2025
MCLGs for radionuclides are as indicated in the following table:
| Contaminant | MCLG |
|---|---|
| 1. Combined radium-226 and radium-228 | Zero. |
| 2. Gross alpha particle activity (excluding radon and uranium) | Zero. |
| 3. Beta particle and photon radioactivity | Zero. |
| 4. Uranium | Zero. |
