RTCR Innovation

Revised Total Coliform Rule (RTCR)

The Revised Total Coliform Rule (RTCR) was finalized in February 2013 and compliance is required starting April 1, 2016.  However, some states have already started requiring compliance with the RTCR requirements.  The following provides a brief outline of the RTCR requirements.

General RTCR Overview

• Monthly monitoring for Total Coliforms, used as an indicator of system integrity.
• Establishes Maximum Contaminant Level (MCL) for E. coli.
• Each total coliform-positive (TC+) routine sample must be tested for the presence of E. coli.
• If any TC+ sample is also E. coli-positive (EC+), then the EC+ sample result must be reported to the state by the end of the day that the PWS is notified.
• If any routine sample is TC+, repeat samples are required, including upstream/downstream sampling.
• Assessments and Corrective Action requirements for EC+ events and repeat TC+ events.

What are the Repeat Sampling Requirements?

Within 24 hours of learning of a TC+ routine sample result, at least 3 repeat samples must be collected and analyzed for total coliform:

• One collected from the same tap as the original sample.
• One collected from within five service connections upstream.
• One collected from within five service connections downstream.

If one or more repeat sample is TC+:

• The TC+ sample must be analyzed for the presence of E. coli.
• If any repeat TC+ sample is also EC+, then the EC+ sample result must be reported to the state by the end of the day that the PWS is notified.
• The PWS must collect another set of repeat samples, unless an assessment has been triggered and the PWS has notified the state.

What Assessments are Required?

The RTCR requires PWSs that have an indication of coliform contamination (e.g., as a result of TC+ samples, E. coli MCL violations, performance failure) to assess the problem and take corrective action. There are two levels of assessments based on the severity or frequency of the problem.

Level 1 Assessments

Level 1 Assessments may be performed by the PWS owner or operator each time a Level 1 Assessment is triggered.  The Level 1 Assessment form must be submitted to the state within 30 days of the Level 1 Assessment being triggered.  Each state may prepare a unique form, so it is important to work directly with state representatives to use the correct form.

A Level 1 Assessment is triggered if any one of the following occurs:

• PWS collecting fewer than 40 samples per month has 2 or more TC+ routine/repeat samples in the same month.
• PWS collecting at least 40 samples per month has greater than 5.0% of the routine/repeat samples in the same month that are TC+.
• PWS fails to take every required repeat sample after any single TC+ sample.

Level 2 Assessments

Level 2 Assessments are performed by the state or state-approved entity each time a Level 2 Assessment is triggered, although the PWS is still responsible for ensuring that the Level 2 Assessment is conducted.  The Level 2 Assessment form must be submitted to the state within 30 days of the Level 2 Assessment being triggered. Each state may prepare a unique form, so it is important to work directly with state representatives to use the correct form.

A Level 2 Assessment is triggered if any one of the following occurs:

• PWS incurs an E. coli MCL violation.
• PWS has a second Level 1 Assessment within a rolling 12-month period.
• PWS on state-approved annual monitoring has a Level 1 Assessment trigger in 2 consecutive years.

What Triggers a Violation?

E.coli MCL Violation - A PWS will receive an E. coli MCL violation when there is any combination of an EC+ sample result with a routine/repeat TC+ or EC+ sample result:

Treatment Technique Violation - A PWS will receive a Treatment Technique violation when any of the following occur:

• Failure to conduct a Level 1 or Level 2 Assessment within 30 days of a trigger.

• Failure to correct all sanitary defects from a Level 1 or Level 2 Assessment within 30 days of a trigger or in accordance with the state-approved timeframe.

• Failure of a seasonal system to complete state-approved start-up procedures prior to serving water to the public.

CEI Case Study

Reoccurring total coliform detections can be a troublesome issue for public water suppliers. To respond to this issue many questions need to be evaluated including: what is the source of the bacteria, where are susceptible areas of the distribution system, are there key time periods when this can be expected to reoccur and what methods can be used to prevent future occurrences?

Total coliforms are used by state and federal public health agencies as an indicator of distribution system integrity. In response to total coliform violations in 2012 and 2013, the Rhode Island Department of Health required one PWS to complete a RTCR Level 2 Assessment of the causes of the total coliform detections and to identify corrective actions.  Comprehensive Environmental Inc. (CEI) was retained by the PWS to complete this study.

CEI completed a thorough review of the potential sources of total coliforms and system conditions for the 2012 and 2013 events.  Additionally, CEI developed a computer model of the water system to simulate system hydraulics and predict water age and residual chlorine levels throughout the system.  Based on this analysis CEI identified the following responses to the five key questions posed at the start of this study:

1. What is the source of the bacteria?
2. How did bacteria enter the distribution system?
3. Where are susceptible areas of the distribution system?
4. Are there key time periods when this can be expected to reoccur?
5. What is the least expensive method to prevent future occurrences?

Download the presentation that describes the process taken to complete the Level 2 assessment, findings from this study and answers to the above five questions.

Responding to Reoccuring Coliform Detects - NEWWA2015