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Revised Total Coliform Rule

The federal Safe Drinking Water Act (SDWA) requires that all public water systems (community and noncommunity) provide an adequate supply of safe drinking water to customers and consumers. The Michigan Department of Environment, Great Lakes, and Energy (EGLE) is responsible for implementing and managing the SDWA at the state level.  One of the regulations is the 1989 Total Coliform Rule (TCR). 

On April 1, 2016, the Revised Total Coliform Rule (RTCR) took effect replacing the TCR regulations. The RTCR establishes a maximum contaminant level (MCL) for E. coli and uses E. coli and total coliforms to initiate a find-and-fix approach to address potential avenues of contamination of the distribution system. 

RTCR Sampling Contingency Plan During the Coronavirus (pdf)

With regard to sampling drinking water for total coliform bacteria, EGLE recognizes that access to some sampling points may be restricted as a result of the COVID-19 mitigation strategies. In the event a routine sampling location(s) is/are not accessible due to the mitigation strategies, please review the guidance to remain in compliance with the Revised Total Coliform Rule (RTCR).

Guidance and Training

Sample Siting Plan

All water supplies must have a current and complete sample siting plan (SSP) on file with EGLE. It is the responsibility of the water supply to update the SSP if there are any changes. A blank copy of the Sample Siting Plan can be found as a Microsoft Word Document or as an Adobe PDF document. If you have more than five (5) distribution sample sites, you may incorporate this sheet (PDF) as part of the SSP.

Bacteriological Site Selection

Sampling sites must be representative of the water throughout the distribution system. Use the Guidance on Bacteriological Site Selection for reference when choosing or revising sample sites.

Bacteriological Sampling Procedure

  1. Collect samples from locations in the SSP. 
  2. Read the sampling instructions carefully.
  3. Make sure the faucet and tap are clean. There should be no attachments on the faucet or tap.
  4. Flame or bleach the tap using a propane torch or bleach (optional - based on system's knowledge and standard practices).
  5. Run water a minimum of 5 minutes, or for time specified in sampling site plan, to flush line for fresh sample. 
  6. Remove cap from sample bottle. Do not touch lip of bottle or inside of cap.
  7. Fill bottle to the neck, leaving an air space at the top.
  8. Recap bottle and secure cap tightly.
  9. Complete laboratory form making sure to include the Water Supply Serial Number (WSSN), sampling site ID (as it appears on the SSP), sample date and sample time.
  10. Submit sample to laboratory immediately. The laboratory testing must begin within 30 hours of collecting the sample.
  11. If there is any deviation from the SSP, please contact your EGLE District Office

RTCR Monitoring and Reporting Requirements for Community Water Supplies

  • The minimum number of samples per month is based on the population served. Monitoring frequency is specified in Safe Drinking Water Rules - Supplying Water to the Public on page 165--Total Coliform Monitoring Frequency for Community and Noncommunity Water Supplies Serving More Than 1,000 People
  • Routine monitoring results are due to EGLE by the 10th of the following month.
  • Contact EGLE by the end of the day for any E. coli-positive sample result.
    • If you cannot contact anyone at EGLE during business hours, call PEAS hotline at 800-292-4706.
  • Contact EGLE after a total coliform-positive sample (recommended).
  • Use this RTCR Compliance Checklist to help track routine monitoring and reporting compliance.

What if my system has a total coliform-positive routine sample?

Repeat and possibly triggered sampling is required.  Use the Routine Positive Flowchart for reference on how to proceed. If you have questions, please contact the district office.


Level 1 assessments are performed by the water supply owner or operator to identify sanitary defects that can cause contamination. Level 2 assessments are more comprehensive and are performed by EGLE staff. Assessments are required when treatment technique triggers occur.

A Level 1 Assessment is triggered by:

  • For supplies collecting 40 samples per month or more; >5% of routine and repeat samples in a month are total coliform-positive.
  • For supplies collecting fewer than 40 samples per month; 2 or more routine and repeat samples in a month are total coliform-positive.
  • The supply fails to take every repeat sample after a total coliform routine sample

The water supply must complete the assessment within 30 days. A blank copy can be found in Word or PDF.

A Level 2 Assessment is triggered by:

  • An E. coli  MCL violation.
  • A second level 1 trigger within a rolling 12-month period

Please contact your district office if you have any questions.


EGLE - Revised Total Coliform Rule (RTCR) and References Webinar, May 2021

AWWA - Small System Online Courses

Related Links

Noncommunity Water Supply

Certified Labs for Microbiological Testing

Association of State Drinking Water Administrators

American Water Works Association


Supplying Water to the Public - Part 1 - Part 28