(a) Chlorite. All public water systems that use chlorine dioxide must comply with the requirements of this subsection.
  (1) Maximum contaminant level (MCL) for chlorite. The chlorite concentration in the water in the distribution system shall not exceed an MCL of 1.0 milligrams per liter (mg/L).
  (2) Monitoring requirements for chlorite. Public water systems shall measure the chlorite concentration at locations and intervals specified in the system's monitoring plan. All samples must be collected during normal operating conditions.
    (A) Each plant using chlorine dioxide must monitor the chlorite concentration in the water entering the distribution system at least once each day. The monitoring frequency at the entry point to the distribution system may not be reduced.
    (B) Each plant using chlorine dioxide must monitor the chlorite concentration in the water within the distribution system at each of the following three locations: at a location near the first customer of a plant using chlorine dioxide; at a location representative of the average residence time in the distribution system; and at a location reflecting maximum residence time in the distribution system. The group of three samples must be collected on the same day and is called a "three-sample set."
      (i) Each system must collect at least one three-sample set each month.
      (ii) If the chlorite concentration entering the distribution system exceeds 1.0 mg/L, the system must collect a three-sample set within 24 hours.
      (iii) The frequency of chlorite monitoring in the distribution system may be reduced to one three-sample set per quarter if none of the entry point or distribution system samples tested during the preceding 12 months contained a chlorite concentration above 1.0 mg/L. A system must revert to the monthly monitoring frequency if the chlorite concentration exceeds 1.0 mg/L in any sample.
  (3) Analytical requirements for chlorite. Analytical procedures required by this section shall be performed in accordance with the requirements of §290.119 of this title (relating to Analytical Procedures).
    (A) The chlorite concentration of the water entering the distribution system must be analyzed at a facility approved by the executive director. The analysis must have a minimum accuracy of 0.05 mg/L.
    (B) The chlorite concentration of the water within the distribution system must be analyzed using ion chromatography at a facility accredited by the executive director.
  (4) Reporting requirements for chlorite. Public water systems that are subject to the provisions of this subsection must ensure the executive director is provided with the results of any test, measurement, or analysis required by this section.
    (A) Systems using chlorine dioxide must submit a Chlorine Dioxide Monthly Operating Report (commission Form 0690) by the tenth day of the month following the end of the reporting period.
    (B) Except where a shorter period is specified in this section, a public water system shall ensure the executive director is provided with a copy of the results of any chlorite test, measurement, or analysis required by paragraph (2)(B) of this subsection within the first ten days following the end of the required monitoring period or ten days following receipt of the results of such test, measurement, or analysis whichever occurs first.
    (C) Reports and analytical results must be mailed to the Water Supply Division, MC 155, Texas Commission on Environmental Quality, P.O. Box 13087, Austin, Texas 78711-3087.
  (5) Compliance determination for chlorite. Compliance with the requirements of this subsection shall be based on the following criteria.
    (A) A public water system that fails to conduct the monitoring tests required by this subsection commits a monitoring violation.
    (B) A public water system that fails to report the results of the monitoring tests required by this subsection commits a reporting violation.
    (C) A public water system commits an MCL violation if the arithmetic average of any three-sample set collected in the distribution system exceeds the MCL for chlorite.
    (D) A public water system that fails to do a required public notice or certify that the public notice has been performed commits a public notice violation.
  (6) Public notification requirements for chlorite. A public water system that violates the requirements of this subsection must notify the executive director and the system's customers.
    (A) A public water system that violates the MCL for chlorite shall notify the executive director by the end of the next business day and the customers in accordance with the requirements of §290.122(b) of this title (relating to Public Notification).
    (B) A public water system which fails to conduct the monitoring required by this subsection must notify its customers of the violation in accordance with the requirements of §290.122(c) of this title.
(b) Bromate. Community and nontransient, noncommunity public water systems that use ozone must comply with the requirements of this subsection beginning on January 1, 2002.
  (1) MCL for bromate. The concentration of bromate at the entry point to the distribution system shall not exceed an MCL of 0.010 mg/L.
  (2) Monitoring requirements for bromate. Each plant using ozone must measure the bromate concentration in the water entering the distribution system at least once each month. The monitoring frequency at the entry point to the distribution system may not be reduced. Samples shall be collected when the ozonation system is operating under normal conditions and at locations and intervals specified in the system's monitoring plan.
  (3) Analytical requirements for bromate. Analytical procedures required by this section shall be performed in accordance with §290.119 of this title. Testing for bromate shall be performed at a laboratory certified by the executive director.
  (4) Reporting requirements for bromate. The owner or operator of a public water system must ensure the executive director is provided with a copy of the results of any test, measurement, or analysis required by this subsection. The copies must be submitted within the first ten days following the month in which the result is received by the public water system, or the first ten days following the end of the required monitoring period as provided by this subsection, whichever occurs first. The copies must be mailed to the Water Supply Division, MC 155, Texas Commission on Environmental Quality, P.O. Box 13087, Austin, Texas 78711-3087.
  (5) Compliance determination for bromate. Compliance with the requirements of this subsection shall be determined using the following criteria.
    (A) A system that fails to monitor in accordance with this section commits a monitoring violation. Failure to monitor will be treated as a violation for the entire period covered by the annual average.
    (B) A public water system that fails to report the results of the monitoring tests required by this subsection commits a reporting violation.
    (C) A public water system violates the MCL for bromate if, at the end of any quarter, the running annual average of monthly averages, computed quarterly, exceeds the maximum contaminant level specified in paragraph (1) of this subsection.
    (D) A public water system that fails to do a required public notice or certify that the public notice has been performed commits a public notice violation.
    (E) A public water system that fails to complete 12 consecutive months' monitoring, compliance with the MCL for the last four-quarter compliance period must be based on an average of the available data.
  (6) Public notification requirements for bromate. A public water system that violates the requirements of this subsection must notify the water system's customers and the executive director.
    (A) A public water system that violates the MCL for bromate shall notify the customers in accordance with the requirements of §290.122(b) of this title.
    (B) A public water system which fails to conduct the monitoring required by this subsection must notify its customers of the violation in accordance with the requirements of §290.122(c) of this title.

Source Note: The provisions of this §290.114 adopted to be effective September 13, 2000, 25 TexReg 8880; amended to be effective May 16, 2002, 27 TexReg 4127; amended to be effective January 9, 2008, 33 TexReg 198; amended to be effective May 15, 2011, 36 TexReg 2860; amended to be effective March 30, 2017, 42 TexReg 1466