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Revised Total Coliform Rule

unfilled RTCR sample bottle
Environment, Great Lakes, and Energy

Revised Total Coliform Rule


John Karnes, Environmental Quality Analyst - West

Karlie Howe, Environmental Quality Analyst - East


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. Total coliform bacteria function as indicator organisms. Their presence indicates a potential pathway allowing contamination into the distribution system exists. The RTCR establishes a maximum contaminant level (MCL) for E. coli.

EGLE Water Sampling 101: Total Coliform Sampling Video

EGLE Water Sampling 101: Total Coliform Sampling

This video will cover how to properly collect a bacteriological drinking water sample to meet the compliance requirements of the Revised Total Coliform Rule.

RTCR Sampling

Sample Siting Plan

Water supplies must have a current 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. The SSP form is now available in MiEHDWIS! Please login to MiEHDWIS, create a Bacteriological Sampling Plan Work Item, and enter the site information directly into the form in the system. For more information on MiEHDWIS, visit and view the MiEHDWIS Sampling Plan instructions.

For water supplies not yet in MiEHDWIS, use the documents below:

Watch the RTCR Bacteriological Sample Siting Plan (SSP) tutorial
Kitchen sink on left, taps on right

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 sampling from their sink

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 for 2 to 5 minutes, or until the temperature has stabilized.
  6. Remove cap from sample bottle. Do not touch lip of bottle or inside of cap.
  7. Fill bottle to the fill line, leaving space at the top. If your bottle has two lines, the water level needs to be between them.
  8. Recap bottle and secure cap tightly.
  9. Completely and accurately fill out all sample paperwork.
  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

cell phone calling "EGLE"

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.
  • Call 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.
diagram of total coliform, fecal coliform, and e.coli

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 find and fix 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.

blue bacteria

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.

contamination of water supply system

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.

RTCR and related rules webinar

This webinar will include an overview of the RTCR and will explain its interaction with other rules of the Safe Drinking Water Act.

View the recorded webinar