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Revised Total Coliform Rule

RTCR sampling bottle on counter
Environment, Great Lakes, and Energy

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) went into effect replacing the old 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 it approach to address potential avenues for the entrance into the distribution system.

RTCR Sampling

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. If you have more than five (5) distribution sample sites, you may incorporate the Distribution System Sample Sites Continued worksheet as part of the SSP.

Watch the RTCR Bacteriological Sample Siting Plan (SSP) Tutorial
RTCR sampling bottle sealed

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.

person taking a drinking water sample at a school drinking fountain

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 in section R325.10704g.
  • 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 1-800-292-4706.
  • 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 Level 1 Assessment Form within 30 days.

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.

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