1. (a) Routine monitoring.

   1. (1) Public water systems must collect routine bacteriological samples at active service connections which are representative of water throughout the distribution system according to a written sample siting plan. Other sampling sites may be used if located adjacent to service connections. These plans are subject to review and revision by the commission.
   2. (2) The bacteriological monitoring frequency for community and non-community water systems is based on the population served by the system, in accordance with the following table.

2. (b) Repeat monitoring.

   1. (1) 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. (A) 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. (B) 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. (2) 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.
   3. (3) 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.
   4. (4) 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 paragraphs (1)-(3) of this subsection. 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. (5) If a system collecting fewer than five routine samples per month has one or more total coliform-positive samples and the commission does not invalidate the sample(s) in accordance with subsection (c) of this section, it must collect at least five routine samples during the next month the system provides water to the public.
   6. (6) 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, after analysis, 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.
   7. (7) Results of all routine and repeat samples not invalidated by the commission must be included in determining compliance with the MCL for total coliforms in accordance with §290.105 of this title (relating to Maximum Bacteriological Contaminant Levels (MCLs) for Microbiological Contaminants).

3. (c) Invalidation of total coliform samples.

   1. (1) A total coliform-positive sample invalidated under this subsection does not count towards meeting the minimum monitoring requirements of this section.

   2. (2) The commission may invalidate a total coliform-positive sample only if one of the following conditions is met:

      1. (A) the laboratory establishes that improper sample analysis caused the total coliform-positive result;
      2. (B) the commission, on the basis of the results of repeat samples collected as required by this section, determines that the total coliform-positive sample resulted from a domestic or other nondistribution system plumbing problem. The commission 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 commission invalidate the sample. The system must provide copies of the routine positive and all repeat samples; or
      3. (C) the commission has substantial grounds to believe that a 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 §290.105 of this title (relating to Maximum Contaminant Levels (MCLs) for Microbiological Contaminants). The system must provide written documentation which must state the specific cause of the total coliform-positive sample, and what action the system has taken, or will take, to correct this problem. The commission may not invalidate a total coliform-positive sample solely on the grounds that all repeat samples are total coliform-negative.
   3. (3) If a laboratory invalidates a sample, 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 re-sample within 24 hours and have the samples analyzed until it obtains a valid result.
4. (d) Fecal coliform bacteria/Escherichia coli (E. coli) testing. 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 commission 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 office is closed, in which case the system must notify the commission before the end of the next business day.

5. (e) Notification to the Texas Natural Resource Conservation Commission (TNRCC).

   1. (1) A public water system which has exceeded the MCL for total coliforms in §290.105 of this title (relating to Maximum Contaminant Levels for Microbiological Contaminants) must report the violation to the commission no later than the end of the next business day after it learns of the violation, and notify the public in accordance with §290.103(8) of this title (relating to Standards of Chemical Quality).
   2. (2) A public water system which has failed to comply with a coliform monitoring requirement must report the monitoring violation to the commission within 10 days after the system discovers the violation, and notify the public in accordance with §290.103(8) of this title (relating to Standards of Chemical Quality).

Source Note:The provisions of this §290.106 adopted to be effective April 15, 1994, 19 TexReg 2282.