Revised Total Coliform Rule

The Revised Total Coliform Rule (RTCR) is efffective April 1, 2016 and utilizes regular bacteria (coliform) monitoring as an indicator for system integrity, to signal possible fecal contamination, and the presence of waterborn pathogens. The RTCR applies to every public drinking water system in Vermont. This new rule is an update to the 1989 Total Coliform Rule and provides some key changes.

Total coliform is a group of bacteria that does not pose an immediate risk to public health by itself. Total coliform exists in all sorts of locations, including plant and soil material, and in digestive tracts of animals but should not be present in finished drinking water. The presence of total coliform in drinking water indicates a potential pathway by which contamination, such as E. coli and other waterborne pathogens (the things that can make you sick) can enter the drinking water distribution system. Instead of sampling for a number of parasites, viruses, and other bacteria, which can be difficult and expensive, total coliform is used as the indicator for how well a system is doing at keeping pathogens out of the water. If total coliform is getting into the water, it means that a pathway exists through which more harmful pathogens can get into the water.

waterborn pathogen venn diagram


Key Changes under the RTCR:

  • There is no more Total Coliform MCL, E. coli MCL remains
  • No more Total Coliform-based Public Notice or Boil Water requirements in Vermont. However, E. coli-based boil and Public Notice within 24 hours remains
  • Systems must take 3 repeat samples for each positive routine sample within 24 hours of learning of the positive sample
  • Systems sampling monthly resume normal monthly monitoring the month following a routine positive sample
  • Systems sampling quarterly must perform 3 additional routine samples the month following a routine positive sample and keep sampling until samples  are absent or increased monitoring is triggered
  • The State cannot waive the requirement to perform routine or repeat samples
  • 2 or more total coliform samples in a month triggers a site assessment
  • Seasonal TNC systems must complete a state-approved startup form and sample on a monthly schedule for the months in which they are open
  • State may require a precautionary boil water notice due to site assessment or ongoing issues
  • E. coli MCL violation requires a boil water notice and a Level 2 Site Assessment

RTCR Guidance

The Division has created a 3-hour training on the Revised Total Coliform Rule. Here is a copy of the presentation.

Site Assessment Resources

If it is the first site assessment triggered in the last 12 months, a level 1 site assessment is triggered when a system has two or more total coliform positive samples in one month or if the system fails to take all required repeat samples following a positive routine sample. If the system triggers a second Level 1 Site Assessment within 12 months or exceeds the E. coli MCL, a Level 2 Site Assessment will need to be performed. Below you will find some guidance on site assessments:

Level 1 Site Assessment Form

Having issues identifying sanitary defects or corrective actions? This is a guidance on sanitary defects and acceptable corrective actions.

RTCR Sampling Plan Forms

Completed Examples:


Completed Example


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