1. (a) Applicability. All public water systems are subject to the requirements of this section.

   1. (1) Community and nontransient non-community systems shall comply with the requirements of this section regarding monitoring, reporting, and maximum contaminant levels (MCLs) for all inorganic contaminants (IOCs) listed in this section.
   2. (2) Transient non-community systems shall comply with the requirements of this section regarding monitoring, reporting, and MCL for nitrate and nitrite.
   3. (3) For purposes of this section, systems using groundwater under the direct influence of surface water shall meet the inorganic sampling requirements given for surface water systems.
2. (b) Maximum contaminant levels for IOCS. The MCLs for IOCs listed in the following table apply to community and nontransient, non-community water systems. The MCLs for nitrate, nitrite, and total nitrate and nitrite also apply to transient non-community water systems.
   Attached Graphic
   

3. (c) Monitoring requirements for IOCs. Public water systems shall monitor for IOCs at the locations specified by the executive director. All monitoring conducted pursuant to the requirements of this section must be conducted at sites designated in the public water system's monitoring plan. Each public water system shall monitor at the time designated during each compliance period.

   1. (1) Monitoring locations for IOCs except asbestos, antimony, arsenic, barium, beryllium, cadmium, chromium, cyanide, fluoride, mercury, nitrate, nitrite, selenium, and thallium shall be monitored at each entry point to the distribution system.

      1. (A) If a system draws water from more than one source and the sources are combined before distribution, the system must sample at an entry point that is representative of all sources and during periods of normal operating conditions when water is representative of all sources being used.
      2. (B) Systems shall take all subsequent samples at the same entry point to the distribution system unless the executive director determines that conditions make another entry point more representative of the source or treatment plant being monitored.

      3. (C) The executive director may approve the use of composite samples.

         1. (i) Compositing must be done in the laboratory or in the field by persons designated by the executive director.
         2. (ii) Compositing shall be allowed only at groundwater entry points to the distribution system.
         3. (iii) Compositing shall be allowed only within a single system. Samples from different systems shall not be included in a composite sample.
         4. (iv) No more than five individual samples shall be included in a composite sample.
         5. (v) The maximum number of individual samples allowed in a composite sample shall not exceed the number obtained by dividing the MCL for the contaminant by the detection limit of the analytical method and rounding the quotient to the next lowest integer. Detection limits for each analytical method are as listed in 40 CFR §141.23(a)(4)(i).

         6. (vi) If the concentration in the composite sample is greater than or equal to the proportional contribution of the MCL (e.g., 20% of MCL when five points are composited) for any inorganic chemical, then a follow-up sample must be collected from each sampling point included in the composite sample.

            1. (I) Follow-up samples must be collected within 14 days of receipt of the composite sample results.
            2. (II) If duplicates of the original sample taken from each entry point to the distribution system used in the composite are available, the system may use these instead of resampling. The duplicates must be analyzed within 14 days of the composite.
            3. (III) The follow-up or duplicate samples must be analyzed for the contaminant(s) which were excessive in the composite sample.

   2. (2) Monitoring locations for asbestos. Asbestos shall be monitored at locations where asbestos contamination is most likely to occur.

      1. (A) A system vulnerable to asbestos contamination due solely to source water shall sample at the entry point to the distribution system.
      2. (B) A system vulnerable to asbestos contamination due solely to corrosion of asbestos-cement pipe shall sample at a tap served by asbestos-cement pipe, under conditions where asbestos contamination is most likely to occur.
      3. (C) A system vulnerable to asbestos contamination due both to its source water supply and corrosion of asbestos-cement pipe shall sample at a tap served by asbestos-cement pipe, under conditions where asbestos contamination is most likely to occur.
      4. (D) The executive director may require additional sampling locations based on the size, length, age, and location of asbestos-cement pipe in the distribution system. The system must provide information regarding the size, length, age, and location of asbestos-cement pipe in the distribution system to the executive director upon request.

   3. (3) Monitoring frequency for IOCs except asbestos, nitrate, and nitrite. Community and nontransient non-community public water systems shall monitor for antimony, arsenic, barium, beryllium, cadmium, chromium, cyanide, fluoride, mercury, selenium, and thallium at the following frequency.

      1. (A) A public water system shall routinely monitor for antimony, arsenic, barium, beryllium, cadmium, chromium, cyanide, fluoride, mercury, selenium, and thallium.

         1. (i) Each groundwater source shall be sampled once every three years at the entry point to the distribution system.
         2. (ii) Each surface water source shall be sampled annually at the entry point to the distribution system.
         3. (iii) Each of the sampling frequencies listed in paragraph (3) of this subsection constitute one round of sampling for groundwater and surface water systems, respectively.

      2. (B) The executive director may reduce the monitoring frequency for a system that has completed a minimum of three rounds of sampling by granting a waiver to the routine monitoring frequency for antimony, arsenic, barium, beryllium, cadmium, chromium, cyanide, fluoride, mercury, selenium, and thallium.

         1. (i) Systems that use a new water source are not eligible for a waiver until three rounds of sampling from the new source have been completed.
         2. (ii) To be considered for a waiver, systems shall demonstrate that all previous analytical results were less than the MCL. At least one sample shall have been taken since January 1, 1990.

         3. (iii) In determining the appropriate reduced monitoring frequency, the executive director shall consider:

            1. (I) the reported contaminant concentrations from all previous samples;
            2. (II) the degree of variation in reported concentrations; and
            3. (III) other factors which may affect contaminant concentrations such as changes in groundwater pumping rates, changes in the system's configuration, changes in the system's operating procedures, or changes in the flow or characteristics of a reservoir or stream used as the water source.
         4. (iv) If the executive director grants a waiver, it shall be made in writing and shall set forth the basis for the determination. The determination may be initiated by the executive director. The executive director shall review and, where appropriate, revise the waiver of monitoring frequency when other data relevant to the system becomes available.
         5. (v) The term during which the waiver is effective shall not exceed one compliance cycle (i.e., nine years).
         6. (vi) A system must take a minimum of one sample during each compliance cycle while the waiver is effective.

      3. (C) The executive director may increase the monitoring frequency for public water systems with sources that exceed the MCL for antimony, arsenic, barium, beryllium, cadmium, chromium, cyanide, fluoride, mercury, selenium, or thallium.

         1. (i) Systems shall sample quarterly beginning in the next quarter after the violation occurs.

         2. (ii) After the initiation of quarterly monitoring, the executive director may return a system to the routine monitoring frequency if monitoring shows that the system is reliably and consistently below the MCL.

            1. (I) The executive director shall not decrease the quarterly sampling requirement until a groundwater system has taken a minimum of two quarterly samples.
            2. (II) The executive director shall not decrease the quarterly sampling requirement until a surface water system has taken a minimum of four quarterly samples.

   4. (4) Asbestos monitoring frequency. Community and nontransient non-community water systems shall monitor for asbestos at the following frequency.

      1. (A) A public water system shall routinely monitor for asbestos once during the first three years of each compliance cycle.

      2. (B) The executive director may waive the routine monitoring frequency requirements for asbestos.

         1. (i) When determining if a waiver should be granted, the executive director shall consider:

            1. (I) the potential for asbestos contamination of the water source;
            2. (II) the use of asbestos-cement pipe for finished water distribution; and
            3. (III) the corrosivity of the water.
         2. (ii) If the executive director grants a waiver, it shall be made in writing and shall set forth the basis for the determination. The determination may be initiated by the executive director. The executive director shall review and, where appropriate, revise the waiver of monitoring frequency when other data relevant to the system becomes available.
         3. (iii) The term during which the waiver is effective shall not exceed one compliance cycle (i.e., nine years).

      3. (C) The executive director may increase the monitoring frequency for asbestos.

         1. (i) A system which exceeds the MCL for asbestos shall sample quarterly beginning in the next quarter after the violation occurs.

         2. (ii) After the initiation of quarterly sampling, the executive director may return a system to the routine monitoring frequency if monitoring shows that the system is reliably and consistently below the MCL.

            1. (I) The executive director shall not decrease the quarterly sampling requirement until a groundwater system has taken a minimum of two quarterly samples.
            2. (II) The executive director shall not decrease the quarterly sampling requirement until a surface (or combined surface water and groundwater) water system has taken a minimum of four quarterly samples.

   5. (5) Nitrate monitoring frequency. All public water systems shall monitor for nitrate at the following frequency.

      1. (A) All public water systems shall routinely monitor for nitrate.

         1. (i) All public water systems shall annually sample each ground water source at the entry point to the distribution system.
         2. (ii) A community or non-transient non-community water system shall sample each surface water source quarterly at the entry point to the distribution system.
         3. (iii) A transient non-community water system shall sample each surface water source annually at the entry point to the distribution system.

      2. (B) The executive director may reduce the monitoring frequency for community or non-transient, non-community water systems using surface water sources by granting a waiver to the routine monitoring frequency.

         1. (i) To be considered for a waiver, a system shall demonstrate that the nitrate concentration in each sample collected during the previous four consecutive quarters was less than 50% of the nitrate MCL.
         2. (ii) If the executive director grants a waiver, it shall be made in writing and shall set forth the basis for the determination. The determination may be initiated by the executive director. The executive director shall review and, where appropriate, revise the waiver of monitoring frequency when other data relevant to the system becomes available.
         3. (iii) A system that receives a waiver to the routine nitrate monitoring frequency must sample annually for nitrate. The annual sample must be collected in the quarter that previously resulted in the highest nitrate concentration.
         4. (iv) A system that is sampling annually shall return to routine quarterly monitoring if the nitrate concentration in any sample is equal to or greater than 50% of the nitrate MCL.

      3. (C) The executive director may increase the nitrate monitoring frequency for community or non-transient, non-community water systems using groundwater sources.

         1. (i) A system that is sampling annually shall begin quarterly nitrate sampling if the nitrate concentration in any sample is equal to or greater than 50% of the nitrate MCL. Quarterly sampling must begin the first quarter after the elevated nitrate level was detected.
         2. (ii) After the initiation of quarterly sampling, the executive director may return a system to the routine annual nitrate monitoring frequency if quarterly sampling shows that the system is reliably and consistently below the nitrate MCL for a minimum of four consecutive quarters.

   6. (6) Nitrite monitoring frequency. All public water systems shall monitor for nitrite at the following frequency.

      1. (A) All public water systems shall routinely take one nitrite sample during the first three years of each compliance cycle.

      2. (B) The executive director may reduce the monitoring frequency for nitrite by granting a waiver to the routine monitoring frequency.

         1. (i) To be considered for a waiver, a system shall demonstrate that the nitrite concentration in the initial sample was less than 50% of the nitrite MCL.
         2. (ii) If the executive director grants a waiver, it shall be made in writing and shall set forth the basis for the determination. The determination may be initiated by the executive director. The executive director shall review and, where appropriate, revise the waiver of monitoring frequency when other data relevant to the system becomes available.
         3. (iii) A system that receives a waiver to the routine nitrite monitoring frequency must sample at a frequency specified by the executive director.

      3. (C) The executive director may increase the monitoring frequency for nitrite.

         1. (i) A system shall sample quarterly for at least one year following any sample in which the nitrite concentration is greater than or equal to 50% of the MCL.
         2. (ii) The executive director may allow a system to return to the routine monitoring frequency after determining the system is reliably and consistently less than the MCL.

   7. (7) Confirmation sampling. The executive director may require a public water system to confirm the results of any individual sample.

      1. (A) If a sample result exceeds the MCL, a public water system shall collect one additional sample to confirm the results of the initial test.

         1. (i) Confirmation samples must be collected at the same entry point to the distribution system as the sample that exceeded the MCL.
         2. (ii) Confirmation samples for IOCs except nitrate and nitrite shall be collected as soon as possible after the system receives the analytical results of the first sample.
         3. (iii) Confirmation samples for nitrate and nitrite shall be collected within 24 hours of the system's receipt of notification of the analytical results of the first sample. Systems unable to comply with the 24-hour sampling requirement must immediately notify the consumers served by the public water system in accordance with subsection (f) of this section. Systems exercising this option must take and analyze a confirmation sample within two weeks of notification of the analytical results of the first sample.
      2. (B) The executive director may require a confirmation sample for any sample with questionable results.
   8. (8) The executive director may require more frequent monitoring than specified in paragraphs (3) - (6) of this subsection.
4. (d) Analytical requirements for IOCs. Analytical procedures shall be performed in accordance with §290.119 of this title (relating to Analytical Procedures). Testing for inorganic contaminants shall be performed at a laboratory certified by the executive director.
5. (e) Reporting requirements for IOCs. Upon the request of the executive director, the owner or operator of a public water system must provide the executive director with a copy of the results of any test, measurement, or analysis required by this subsection. The copies must be submitted within ten days of the request or within ten days of their receipt by the public water system, whichever is later. The copies must be mailed to the Texas Natural Resource Conservation Commission, Water Supply Division, MC 155, P.O. Box 13087, Austin, Texas 78711-3087.

6. (f) Compliance determination for IOCs. Compliance with this section shall be determined using the following criteria.

   1. (1) Compliance with the MCL for each IOC shall be based on the analytical results obtained at each individual sampling point.
   2. (2) A public water system that exceeds the levels for nitrate, nitrite, or the sum of nitrate and nitrite specified in subsection (b) of this section commits an acute MCL violation. Compliance shall be based on the results of the single sample. If a confirmation sample is collected, compliance shall be based on the average result of the original and confirmation samples.

   3. (3) A public water system that exceeds the levels of antimony, arsenic, asbestos, barium, beryllium, cadmium, chromium, cyanide, fluoride, mercury, selenium, or thallium (i.e., any IOC except nitrate and nitrite) specified in subsection (b) of this section commits an MCL violation.

      1. (A) For systems that are sampling annually or less frequently, compliance may be based on the results of a single sample, if a confirmation sample is not collected.
      2. (B) For systems that are sampling annually or less frequently, if a confirmation sample is collected, compliance will be based on the average result of the original and confirmation samples.
      3. (C) For systems that are sampling more frequently than annually, compliance is based on the running annual average for each sampling point.
      4. (D) If a single quarterly sample would cause the running annual average to be exceeded, then the system is immediately out of compliance.
   4. (4) Any result below the method detection limit shall be considered to be zero for the purpose of calculating compliance.
   5. (5) The executive director may exclude the results of obvious sampling errors from the compliance calculations.

7. (g) Public notice for IOCs. A public water system that violates the requirements of this section must notify the executive director and the system's customers.

   1. (1) A public water system that violates the MCL for nitrate, nitrite, or the sum of nitrate and nitrite shall notify the executive director by the next business day and the water system customers of this acute violation in accordance with the requirements of §290.122(a) of this title (relating to Public Notification).
   2. (2) A public water system that violates the MCL for nitrate, nitrite, or the sum of nitrate and nitrite that is unable to comply with the 24-hour confirmation sampling requirement must immediately notify the consumers served by the public water system in accordance with §290.122(a) of this title.
   3. (3) A public water system that fails to meet the MCL for any of the regulated IOCs except nitrate and nitrite (i.e., antimony, arsenic, asbestos, barium, beryllium, cadmium, chromium, cyanide, fluoride, mercury, selenium, and thallium) shall notify the executive director by the end of the next business day and the water system customers in accordance with the requirements of §290.122(b) of this title.
   4. (4) A public water system which fails to conduct the monitoring required by this section must notify its customers of the violation in accordance with the requirements of §290.122(c) of this title.
   5. (5) If a public water system has a distribution system separable from other parts of the distribution system with no interconnections, the executive director may allow the system to give public notice to only the area served by that portion of the system which is out of compliance.
8. (h) Best Available Technology (BAT) for IOCs. BAT for treatment of violations of MCLs in subsection (b) of this section are listed in 40 CFR §141.62.

Source Note:The provisions of this §290.106 adopted to be effective September 13, 2000, 25 TexReg 8880; amended to be effective May 16, 2002, 27 TexReg 4127.