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What To Do After You Receive a Total Coliform Positive on a Routine Distribution Sample

Actions to take after a routine distribution sample tests positive for total coliform at your public water system.

What to do if I Collect a Routine Distribution Sample that is Positive for Total Coliform

Your public water system (PWS) must complete the following steps within 24 hours of routine positive sample result notification from your lab.

  1. Collect three repeat samples as listed in your Sample Siting Plan (SSP).
    1. One at the original positive location.
    2. One upstream within five service connections from the original positive location.
    3. One downstream within five service connections from the original positive location.
  2. If your PWS has less than three service connections, you must still collect three repeat samples. Contact the Revised Total Coliform Rule (RTCR) program if you have questions.
  3. Mark all repeat samples as sample type REPEAT on the Microbial Reporting Form (MRF).
    1. If multiple sample types are selected the samples will be rejected by the lab.
  4. If your PWS has groundwater wells you must collect a raw sample from each well that was active when the routine sample was collected.
    1. A raw well sample must be collected for each routine positive sample. See What to do if I have Multiple Wells or Inactive Wells.
  5. Mark raw well samples as sample type RAW WELL on the MRF.
  6. Write the disinfectant residual for all samples collected.
    1. You must use a numeric value (for example, 0).
    2. Select the type of chlorine disinfection used (Free or Total).
    3. Do not leave this field blank or write N/A, or the lab will reject the sample.
  7. Include the original positive sample ID and date of collection on the MRF for all samples collected.

MRF Example

The application/pdfRTCR Repeat Sampling Requirements Diagram shows an example MRF and is a good resource to keep at your PWS.

If any of the REPEAT samples, not raw well samples, are positive please go to What to do if Repeat Samples are Positive. 

If you have any questions about repeat sampling requirements, contact the RTCR program at TCRData@tceq.texas.gov or (512) 239-4691 and ask for RTCR. If you have any questions about raw well sampling requirements, contact the Groundwater Rule (GWR) program at GWRData@tceq.texas.gov or (512) 239-4691 and ask for GWR.

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What to do if I have Multiple Wells or Inactive Wells

If you have more than one well, below are some examples about how many raw well samples you must collect.  

  • A PWS that has two active wells (A and B) and collected one positive routine sample (Site 1) must collect one raw well sample from each well.
    • A total of two raw samples must be collected, one from well A and one from well B.
  • A PWS that has two active wells (A and B) and collected two positive routine samples (Site 1 and Site 2) must collect two raw well samples from each well.
    • A total of four raw well samples must be collected, two from well A and two from well B.

If any wells listed as active on Drinking Water Watch were not in use at the time of the routine distribution positive sample:

  1. Complete application/pdfGroundwater Rule Notification of Inactive Well(s) for Triggered and Assessment Source Monitoring
  2. Email it to GWRData@tceq.texas.gov

If you have any questions about your wells or raw well sampling contact the GWR program at GWRData@tceq.texas.gov or (512) 239-4691, ask for GWR.

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What To Do If Repeat Samples Are Total Coliform Positive after a Positive Routine Distribution Sample

When repeat samples are positive for total coliform, your PWS must complete the following actions based on the number of samples you are required to collect per month.

PWSs collecting less than 40 distribution samples per month

  1. No additional repeat samples are required.
  2. An assessment is triggered, and you must complete it within 30 days.

PWSs collecting 40 or more distribution samples per month

  1. Collect the three repeat samples from the same locations previously used until one of the following is met. See example figure below.
    1. A full set of repeats tests negative OR
    2. The number of positive distribution samples exceeds 5% of the total number of distribution samples collected for the month.
  2. Once a or b is met then no additional repeats are required.
  3. If more than 5% of samples are positive an assessment is triggered, and you must complete it within 30 days.

The figure below shows how the repeat samples must be collected after positive repeat samples.

Number of samples to be collected after a total coliform positive.

For questions about positive repeat samples contact the RTCR program at TCRData@tceq.texas.gov or (512) 239-4691 and ask for RTCR.

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What to do if a Repeat Sample is E. coli Positive

Please contact the RTCR program as soon as possible at (512) 239-4691 and ask for RTCR or email TCRData@tceq.texas.gov.