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TCR Sample Invalidation Instructions

Instructions for requesting an invalidation of a total coliform-found (positive) Routine/Distribution or repeat sample result.

Before requesting an invalidation of a total coliform-found (positive) Routine/Distribution or Repeat sample result, please read the following information:

Sample results will not be invalidated:

  • If all required Repeat samples were collected more than 24-hours after lab notification of the positive result (lab hours and weather permitting);
  • Solely because the Repeat sample results were negative;
  • If either the original coliform-found sample or any Repeat sample is fecal/E. coli positive;
  • If the Invalidation Request is submitted more than 14 days after the coliform-found sample collection date.

Submit all required documents including a brief cover letter which provides a specific, single reason why the result was not representative of the water quality of the distribution system at the time of sampling with the TCR Invalidation Request Form.

If the invalidation request is weather-related, provide proof that precipitation or wind speed exceeding 20 mph occurred at the time of sample collection. Only one invalidation request will be considered due to weather; all subsequent requests will be denied. If necessary, select alternative sites that are located out of the wind, or use indoor sites that have been checked first by collecting 'special' samples to ensure the location will not routinely give positive results.

If the repeat sample collected from the location of the original positive result is also positive and all other repeat results are negative, this indicates a contaminated sample site and may qualify for invalidation. However, all required documentation for the invalidation must still be submitted. (This type of invalidation applies only to community water systems; non-community systems which collect all repeat samples from one tap and have a mix of positive and negative results will not receive invalidation.)

The result of your invalidation request may be found on the TCEQ's Drinking Water Watch website. Alternatively, you may include an email address on your Invalidation Request Checklist for a follow-up email after your request has been processed.

If you have questions concerning the invalidation process, please call a member of the Total Coliform Rule program at (512) 239-4691.

Fax all required documents to:
(512) 239 - 3666

Or mail to:

TCR Program
PO Box 13087
Austin, TX 78711-3087