1. (a) Applicability. All public water systems must produce and distribute water that meets the provisions of this section regarding microbial contaminants.

2. (b) Maximum contaminant levels (MCL) for microbial contaminants. The MCL for microbial contaminants if based on the presence or absence of total coliform bacteria in a sample.

   1. (1) For a system which collects at least 40 bacteriological samples per month, the MCL is 5.0% total coliform-positive samples, of the samples collected during the month.
   2. (2) For a system which collects fewer than 40 samples/month, the MCL is one total coliform-positive sample, of the samples collected during the month.

3. (c) Monitoring requirements for microbial contaminants. Public water systems shall collect samples for total coliform and for fecal coliform or Escherichia coli. All compliance samples must be collected during normal operating conditions.

   1. (1) Routine microbial sampling locations. Public water systems shall routinely monitor for microbial contaminants at the following locations.

      1. (A) Public water systems must collect routine bacteriological samples at active service connections which are representative of water throughout the distribution system. Other sampling sites may be used if located adjacent to service connections.
      2. (B) Public water systems shall monitor for microbial contaminants at locations specified in the system's monitoring plan.

   2. (2) Routine microbial sampling frequency. Public water systems must sample for microbiological contaminants at the following frequency.

      1. (A) Community and noncommunity public water systems must collect routine bacteriological samples at a frequency based on the population served by the system:

         1. (i) the population for noncommunity systems will be based on the maximum number of persons served on any given day during the month;
         2. (ii) the population of community systems will be based on the data reported during the most recent sanitary survey of the public water system; and
         3. (iii) the minimum sampling frequency for public water systems is shown in the following table.
            Attached Graphic
            
      2. (B) A public water system which uses surface water or groundwater under the direct influence of surface water must collect samples at regular time intervals throughout the month.
      3. (C) A public water system which uses only uses only purchased water or groundwater not under the direct influence of surface water and serves more than 4,900 persons must collect samples at regular time intervals throughout the month.
      4. (D) A public water system which uses only purchased water or groundwater not under the direct influence of surface water and serves 4,900 persons or fewer may collect all required samples on a single day if they are taken from different sites.
      5. (E) A total coliform-positive sample invalidated under this subsection does not count towards meeting the minimum routine monitoring requirements of this subsection.
      6. (F) If a system collecting fewer than five routine samples per month has one or more total coliform-positive samples and the executive director does not invalidate the sample(s) in accordance with subsection (c)(4) of this section, it must collect at least five routine samples during the next month the system provides water to the public.

   3. (3) Repeat microbial monitoring requirements. Systems shall conduct repeat monitoring if one or more of the routine samples is found to contain coliform organisms.

      1. (A) If a routine sample is total coliform-positive, the public water system must collect a set of repeat samples within 24 hours of being notified of the positive result, or as soon as possible if the local laboratory is closed.

         1. (i) A system which collects more than one routine sample per month must collect no fewer than three repeat samples for each total coliform-positive sample found.
         2. (ii) A system which collects one routine sample per month must collect no fewer than four repeat samples for each total coliform-positive sample found.
      2. (B) The system must collect all repeat samples on the same day, except that a system with a single service connection may collect daily repeat samples until the required number of repeat samples has been collected.
      3. (C) The system must collect at least one repeat sample from the sampling tap where the original total coliform-positive sample was taken, and at least one repeat sample at a tap within five service connections upstream and at least one repeat sample at a tap within five service connections downstream of the original sampling site. If a fourth repeat sample is required, it must be collected within five service connections upstream or downstream. If the positive routine sample was collected at the end of the distribution line, one repeat sample must be collected at that point and all other samples must be collected within five connections upstream of that point.
      4. (D) If one or more repeat samples in the set is total coliform-positive, the public water system must collect an additional set of repeat samples in the manner specified in subparagraphs (A) - (C) of this paragraph. The additional samples must be collected within 24-hours of being notified of the positive result or as soon as possible if the local laboratory is closed. The system must repeat this process until either total coliforms are not detected in one complete set of repeat samples or the system determines that the MCL for total coliforms has been exceeded.
      5. (E) After a system collects a routine sample and before it learns the results of the analysis of that sample, if it collects another routine sample(s) from within five adjacent service connections of the initial sample, and the initial sample is found to contain total coliform bacteria, then the system may count the subsequent sample(s) as a repeat sample instead of as a routine sample.

   4. (4) Sample invalidation. The executive director may invalidate a total coliform-positive sample if one of the following conditions is met.

      1. (A) The executive director may invalidate a sample if the laboratory establishes that improper sample analysis caused the total coliform-positive result.
      2. (B) The executive director may invalidate a sample if the results of repeat samples collected as required by this section determines that the total coliform-positive sample resulted from a domestic or other non-distribution system plumbing problem. The executive director cannot invalidate a sample on the basis of repeat sample results unless all repeat sample(s) collected at the same tap as the original total coliform-positive sample are also total coliform-positive, and all repeat samples collected within five service connections of the original tap are total coliform-negative. Under those circumstances, the system may cease resampling and request that the executive director invalidate the sample. The system must provide copies of the routine positive and all repeat samples.
      3. (C) The executive director may invalidate a sample if there are substantial grounds to believe that the total coliform-positive result is due to a circumstance or condition which does not reflect water quality in the distribution system. In this case, the system must still collect all repeat samples required by this section, and use them to determine compliance with the MCL for total coliforms in subsection (f) of this section. The system must provide written documentation which must state the specific cause of the total coliform-positive sample, and the action the system has taken, or will take, to correct this problem. The executive director may not invalidate a total coliform-positive sample solely on the grounds that all repeat samples are total coliform-negative.
      4. (D) The executive director may invalidate a sample if the laboratory establishes that the sample was unsuitable for analysis.
      5. (E) If a sample is invalidated, the system must collect another sample from the same location as the original sample within 24-hours of being notified, or as soon as possible if the laboratory is closed, and have it analyzed for the presence of total coliforms. The system must continue to resample within 24 hours and have the samples analyzed until it obtains a valid result.
   5. (5) Culture analysis. If any routine or repeat sample is total coliform-positive, that total coliform-positive culture medium will be analyzed to determine if fecal coliforms or E. coli bacteria are present. If fecal coliforms or E. coli are present, the system must notify the executive director by the end of the day in accordance with subsection (g) of this section.
4. (d) Analytical requirements for microbial contaminants. Analytical procedures shall be performed in accordance with §290.119 of this title (relating to Analytical Procedures). Testing for microbial contaminants shall be performed at a laboratory certified by the executive director.
5. (e) Reporting requirements for microbial contaminants. 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 microbial contaminants. Compliance with the requirements of this section shall be determined using the following criteria each month that the system is in operation.

   1. (1) A system commits an acute MCL violation if:

      1. (A) A repeat sample is fecal coliform-positive or Escherichia coli -positive; or
      2. (B) A total coliform-positive repeat sample follows a fecal coliform-positive or Escherichia coli -positive routine sample.
   2. (2) A system that collects at least 40 bacteriological samples per month commits a nonacute MCL violation if more than 5.0 % of the samples collected during a month are total coliform-positive, but none of the initial or repeat samples are fecal coliform-positive or Escherichia coli-positive.
   3. (3) A system that collects fewer than 40 samples per month commits a nonacute MCL violation if more than one sample collected during a month is total coliform-positive, but none of the initial or repeat samples are fecal coliform-positive or Escherichia coli -positive.
   4. (4) A public water system that fails to provide the required number of suitable samples commits a monitoring violation.
   5. (5) A public water system that fails to report the results of the monitoring tests required by this section commits a reporting violation.
   6. (6) Results of all routine and repeat samples not invalidated by the executive director must be included in determining compliance with the MCL for total coliforms.
   7. (7) Samples invalidated by the executive director shall not be included in determining compliance with the MCL for total coliforms.
   8. (8) Special purpose samples, such as those taken to determine whether disinfection practices are sufficient following pipe placement, replacement, or repair, shall not be used to determine compliance with the MCL for microbiological contaminants.

7. (g) Public notification for microbial contaminants. A system that is out of compliance with the requirements described in this section must notify the public using the procedures described in §290.122 of this title for microbial contamination.

   1. (1) A public water system that commits an acute MCL violation for microbial contaminants must notify the water system customers in accordance with the requirements of §290.46(s)(3) of this title (relating to Minimum Acceptable Operating Practices for Public Drinking Water Systems) and §290.122(a) of this title.
   2. (2) A public water system that has fecal coliforms or E. coli present must notify the executive director by the end of the day when the system is notified of the test result, unless the system is notified of the result after the commission's office is closed, in which case the system must notify the executive director before the end of the next business day.
   3. (3) A public water system which commits an MCL violation must report the violation to the executive director immediately after it learns of the violation, but no later than the end of the next business day, and notify the public in accordance with §290.122(b) of this title.
   4. (4) A public water system which has failed to comply with a coliform monitoring requirement must report the monitoring violation to the executive director within ten days after the system discovers the violation and notify the public in accordance with §290.122(c) of this title.

Source Note:The provisions of this §290.109 adopted to be effective September 13, 2000, 25 TexReg 8880; amended to be effective May 16, 2002, 27 TexReg 4127.