View all text of Subpart G [§ 141.60 - § 141.66]

§ 141.66 - Maximum contaminant levels for radionuclides.

(a) [Reserved]

(b) MCL for combined radium-226 and -228. The maximum contaminant level for combined radium-226 and radium-228 is 5 pCi/L. The combined radium-226 and radium-228 value is determined by the addition of the results of the analysis for radium-226 and the analysis for radium-228.

(c) MCL for gross alpha particle activity (excluding radon and uranium). The maximum contaminant level for gross alpha particle activity (including radium-226 but excluding radon and uranium) is 15 pCi/L.

(d) MCL for beta particle and photon radioactivity. (1) The average annual concentration of beta particle and photon radioactivity from man-made radionuclides in drinking water must not produce an annual dose equivalent to the total body or any internal organ greater than 4 millirem/year (mrem/year).

(2) Except for the radionuclides listed in table A, the concentration of man-made radionuclides causing 4 mrem total body or organ dose equivalents must be calculated on the basis of 2 liter per day drinking water intake using the 168 hour data list in “Maximum Permissible Body Burdens and Maximum Permissible Concentrations of Radionuclides in Air and in Water for Occupational Exposure,” NBS (National Bureau of Standards) Handbook 69 as amended August 1963, U.S. Department of Commerce. This incorporation by reference was approved by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies of this document are available from the National Technical Information Service, NTIS ADA 280 282, U.S. Department of Commerce, 5285 Port Royal Road, Springfield, Virginia 22161. The toll-free number is 800-553-6847. Copies may be inspected at EPA's Drinking Water Docket, 401 M Street, SW., Washington, DC 20460; or at the National Archives and Records Administration (NARA). For information on the availability of this material at NARA, call 202-741-6030, or go to: If two or more radionuclides are present, the sum of their annual dose equivalent to the total body or to any organ shall not exceed 4 mrem/year.

Table A - Average Annual Concentrations Assumed To Produce: a Total Body or Organ Dose of 4 mrem/yr

1. RadionuclideCritical organpCi per liter
2. TritiumTotal body20,000
3. Strontium-90Bone Marrow8

(e) MCL for uranium. The maximum contaminant level for uranium is 30 µg/L.

(f) Compliance dates. (1) Compliance dates for combined radium-226 and -228, gross alpha particle activity, gross beta particle and photon radioactivity, and uranium: Community water systems must comply with the MCLs listed in paragraphs (b), (c), (d), and (e) of this section beginning December 8, 2003 and compliance shall be determined in accordance with the requirements of §§ 141.25 and 141.26. Compliance with reporting requirements for the radionuclides under appendix A to subpart O and appendices A and B to subpart Q is required on December 8, 2003.

(2) [Reserved]

(g) Best available technologies (BATs) for radionuclides. The Administrator, pursuant to section 1412 of the Act, hereby identifies as indicated in the following table the best technology available for achieving compliance with the maximum contaminant levels for combined radium-226 and -228, uranium, gross alpha particle activity, and beta particle and photon radioactivity.

Table B - BAT for Combined Radium-226 and Radium-228, Uranium, Gross Alpha Particle Activity, and Beta Particle and Photon Radioactivity

Contaminant BAT
1. Combined radium-226 and radium-228Ion exchange, reverse osmosis, lime softening.
2. UraniumIon exchange, reverse osmosis, lime softening, coagulation/filtration.
3. Gross alpha particle activity (excluding Radon and Uranium)Reverse osmosis.
4. Beta particle and photon radioactivityIon exchange, reverse osmosis.

(h) Small systems compliance technologies list for radionuclides.

Table C - List of Small Systems Compliance Technologies for Radionuclides and Limitations to Use

Unit technologies Limitations (see footnotes) Operator skill level required 1Raw water quality range and
considerations. 1
1. Ion exchange (IE)( a)IntermediateAll ground waters.
2. Point of use (POU 2) IE( b)BasicAll ground waters.
3. Reverse osmosis (RO)( c)AdvancedSurface waters usually require pre-filtration.
4. POU 2 RO( b)BasicSurface waters usually require pre-filtration.
5. Lime softening( d)AdvancedAll waters.
6. Green sand filtration( e)Basic.
7. Co-precipitation with Barium sulfate( f)Intermediate to AdvancedGround waters with suitable water quality.
8. Electrodialysis/electrodialysis reversalBasic to IntermediateAll ground waters.
9. Pre-formed hydrous Manganese oxide filtration( g)IntermediateAll ground waters.
10. Activated alumina( a), ( h)AdvancedAll ground waters; competing anion concentrations may affect regeneration frequency.
11. Enhanced coagulation/filtration( i)AdvancedCan treat a wide range of water qualities.

1 National Research Council (NRC). Safe Water from Every Tap: Improving Water Service to Small Communities. National Academy Press. Washington, D.C. 1997.

2 A POU, or “point-of-use” technology is a treatment device installed at a single tap used for the purpose of reducing contaminants in drinking water at that one tap. POU devices are typically installed at the kitchen tap. See the April 21, 2000 NODA for more details.

Limitations Footnotes: Technologies for Radionuclides:

a The regeneration solution contains high concentrations of the contaminant ions. Disposal options should be carefully considered before choosing this technology.

b When POU devices are used for compliance, programs for long-term operation, maintenance, and monitoring must be provided by water utility to ensure proper performance.

c Reject water disposal options should be carefully considered before choosing this technology. See other RO limitations described in the SWTR Compliance Technologies Table.

d The combination of variable source water quality and the complexity of the water chemistry involved may make this technology too complex for small surface water systems.

e Removal efficiencies can vary depending on water quality.

f This technology may be very limited in application to small systems. Since the process requires static mixing, detention basins, and filtration, it is most applicable to systems with sufficiently high sulfate levels that already have a suitable filtration treatment train in place.

g This technology is most applicable to small systems that already have filtration in place.

h Handling of chemicals required during regeneration and pH adjustment may be too difficult for small systems without an adequately trained operator.

i Assumes modification to a coagulation/filtration process already in place.

Table D - Compliance Technologies by System Size Category for Radionuclide NPDWR's

Contaminant Compliance technologies 1 for system size categories (population served) 3,300-10,000
25-500 501-3,300
1. Combined radium-226 and radium-2281, 2, 3, 4, 5, 6, 7, 8, 91, 2, 3, 4, 5, 6, 7, 8, 91, 2, 3, 4, 5, 6, 7. 8, 9.
2. Gross alpha particle activity3, 43, 43, 4.
3. Beta particle activity and photon activity1, 2, 3, 41, 2, 3, 41, 2, 3, 4.
4. Uranium1, 2, 4, 10, 111, 2, 3, 4, 5, 10, 111, 2, 3, 4, 5, 10, 11.

Note: 1 Numbers correspond to those technologies found listed in the table C of 141.66(h).

[65 FR 76748, Dec. 7, 2000]