Drinking Water:

(40CFR141.66 – Updated Based Upon Final Radionuclides Rule 66 FR 76708, December 7, 2000, Vol. 65, No. 236)

  • Gross Alpha Activity – MCL = 15 pCi/L (Not including Radon and Uranium)
  • Combined Radium-226 and Radium-228 (Sum of the individual concentrations) – MCL = 5 pCi/L
  • Total Uranium – 30 ug/L
  • Beta Particle and Photon Activity – Concentration resulting in an annual dose to the total body or any internal organ greater than 4 millirem/yr. Note: Monitoring is not required for most suppliers. MCLs for systems determined to be vulnerable to beta and photon contamination are:
    • Gross Beta (minus natural K-40) – 50 pCi/L
    • Tritium – 20,000 pCi/L
    • Strontium-90 – 8 pCi/L

Soil and Other Environmental Media:

There are no universal MCLs for soil and sediment. Allowable levels are determined by assessing the dose or risk posed to the environment or public. These levels vary depending upon the specific isotopes present, exposure pathways and future use of the contaminated area.