1. (a) Maximum contaminant levels for radium-226, radium-228, and gross alpha particle radioactivity for community systems:

   1. (1) combined radium-226 and radium-228--5 pCi/liter;
   2. (2) gross alpha particle activity (including radium-226 but excluding radon and uranium)--15 pCi/liter.

2. (b) Maximum contaminant levels for beta particle and photon radioactivity from man-made radionuclides in drinking water in community water systems.

   1. (1) The average annual concentration of beta particle and photon radioactivity from man-made radionuclides in drinking water shall not produce an annual dose equivalent to the total body or any internal organ greater than four millirem (mrem)/year.
   2. (2) Except for the radionuclides listed in Table A, the concentration of man-made radionuclides causing four mrem total body or organ dose equivalents shall be calculated on the basis of a two-liter-per-day drinking water intake using the 168 hour data listed in Maximum Permissible Body Burdens and Maximum Permissible Concentration of Radionuclides in Air or Water for Occupational Exposure, NBS Handbook 69 as amended August 1963, United States Department of Commerce. 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 four mrem/year.

3. (c) Monitoring frequency for radioactivity in community water systems.

   1. (1) Monitoring requirements for gross alpha particle activity, radium-226, and radium-228.

      1. (A) Compliance with subsection (a) of this section shall be based on the analysis or analyses of four quarterly samples.

         1. (i) A gross alpha particle activity measurement may be substituted for the required radium-226 and radium-228 analysis provided that the measured gross alpha particle activity does not exceed five pCi/liter at a confidence level of 95% (1.65 o where o is the standard deviation of the net counting rate of the sample.)
         2. (ii) When the gross alpha particle activity exceeds five pCi/liter, the same or an equivalent sample shall be analyzed for radium-226. If the concentration of radium-226 exceeds three pCi/liter the same or an equivalent sample shall be analyzed for radium-228.

      2. (B) Suppliers of water shall monitor at least once every four years following the procedure required by subparagraph (A) of this paragraph. At the discretion of the commission, when an annual record taken in conformance with subparagraph (A) of this paragraph has established that the average annual concentration is less than one-half the maximum contaminant levels established by subsection (a) of this section, analysis of a single sample may be substituted for the quarterly sampling procedure required by subparagraph (A) of this paragraph.

         1. (i) More frequent monitoring shall be conducted when required by the commission in the vicinity of mining or other operations which may contribute alpha particle radioactivity to either surface or groundwater sources of drinking water, or when changes in the distribution system or treatment processing occur which may increase the concentration of radioactivity in the finished water.
         2. (ii) A supplier of water shall monitor in conformance with subparagraph (A) of this paragraph within one year of the introduction of new water source for a community water system.
         3. (iii) A community water system using two or more sources having different concentrations of radioactivity shall monitor the source of water, in addition to water from a free-flowing tap, when required by the commission.
         4. (iv) Monitoring for compliance with subsection (a) of this section after the initial period need not include radium-228 provided that the average concentration of radium-228 has been assayed at least once using the quarterly sampling procedure required by subparagraph (A) of this paragraph.
         5. (v) Suppliers of water shall conduct annual monitoring of any community water system in which the radium-226 concentration exceeds three pCi/liter when required by the commission.
      3. (C) If the average annual maximum contaminant level for gross alpha particle activity or total radium as set forth in subsection (a) of this section is exceeded, the supplier of a community water system shall give notice to the commission and notify the public as required by §290.103(8) of this title (relating to Standards of Chemical Quality). Monitoring at quarterly intervals shall be continued until the annual average concentration no longer exceeds the maximum contaminant level or until a monitoring schedule as a condition to a variance, exemption, or enforcement action shall become effective.

   2. (2) Monitoring requirements for man-made radioactivity in community water systems.

      1. (A) Systems using surface water sources and serving more than 100,000 persons and such other community water systems as are designated by the commission shall be monitored for compliance with subsection (b) of this section by analysis of four quarterly samples. Compliance with subsection (b) of this section may be assumed without further analysis if the average annual concentration of gross beta particle activity is less than 50 pCi/liter and if the average annual concentrations of tritium and strontium-90 are less than those listed in Table A of subsection (b)(2) of this section, provided that if both radionuclides are present, the sum of their annual dose equivalents to bone marrow shall not exceed four millirem/year.

         1. (i) If the gross beta particle activity exceeds 50 pCi/liter, an analysis of the sample must be performed to identify the major radioactive constituents present and the appropriate organ and total body doses shall be calculated to determine compliance with subsection (b) of this section.
         2. (ii) Suppliers of water shall conduct additional monitoring, as required by the commission to determine the concentration of man-made radioactivity in principal watersheds designated by the commission.
         3. (iii) At the discretion of the commission, suppliers of water utilizing only groundwaters may be required to monitor for man-made radioactivity.
      2. (B) After the initial analysis required by subparagraph (A) of this paragraph, suppliers of water shall monitor at least every four years following the procedure given in subparagraph (A) of this paragraph.

      3. (C) The supplier of any community water system designated by the commission as utilizing waters contaminated by effluents from nuclear facilities shall initiate quarterly monitoring for gross beta particle and iodine-131 radioactivity and annual monitoring for strontium-90 and tritium.

         1. (i) Quarterly monitoring for gross beta particle activity shall be based on the analysis of monthly samples. If the gross beta particle activity in a sample exceeds 15 pCi/liter, the same or an equivalent sample shall be analyzed for strontium-89 and cesium-134. If the gross beta particle activity exceeds 50 pCi/liter, an analysis of the sample must be performed to identify the major radioactive constituents present and the appropriate organ and total body doses shall be calculated to determine compliance with subsection (b) of this section.
         2. (ii) For iodine-131, a composite of five consecutive daily samples shall be analyzed once each quarter. When iodine-131 is identified in the finished water more frequent monitoring shall be conducted as required by the commission.
         3. (iii) Annual monitoring for strontium-90 and tritium shall be conducted by the analysis of four quarterly samples.
         4. (iv) The commission may allow the substitution of environmental surveillance data taken in conjunction with a nuclear facility for direct monitoring of man-made radioactivity by the supplier of water where the commission determines such data is applicable to a particular community water system.
      4. (D) If the average annual maximum contaminant level for man-made radioactivity set forth in subsection (b) of this section is exceeded, the operator of a community water system shall give notice to the commission and to the public as required by §290.103(6) of this title (relating to Standards of Chemical Quality). Monitoring at monthly intervals shall be continued until the concentration no longer exceeds the maximum contaminant level or until a monitoring schedule as a condition to a variance, exemption, or enforcement action shall become effective.

Source Note:The provisions of this §290.110 adopted to be effective April 15, 1994, 19 TexReg 2282.