Revised Total Coliform Rule

Overview

Beginning July 1, 2021, the California Revised Total Coliform Rule (RTCR) will become effective. The revisions include the new Coliform Treatment Technique requirement replacing the Total Coliform MCL, and a new E.coli MCL regulatory limit. The Revised Total Coliform Rule establishes a “find-and-fix” approach for investigating and correcting causes of coliform problems within water distribution systems

Under the headings below, you will find guidance and forms to help comply with the RTCR requirements.

Final Regulation Text

Bacteriological Sample Siting Plans

Existing bacteriological sample siting plans may comply with the new State RTCR requirements provided the plans:

  1. Include the minimum number of routine samples per month in Table 64423-A of the regulations.
  2. Identify repeat sample locations for each routine sample location
  3. Identify triggered source sampling needed to comply with the Groundwater Rule
  4. Identify the sample schedule and rotation plan among sampling sites for collection of routine, repeat and triggered source sampling
  5. Identify the raw water sources that are continuously disinfected and require quarterly monitoring.

If your existing plan does not include the additional requirements above, please submit a new plan to your local regulating agency (DDW District Office or Local Primacy Agency , e.g. County Environmental Health Office). Guidance for creating a bacteriological sample siting plan is available from your local regulating agency. A template bacteriological sample siting plan for small water systems is available below.

  • Bacteriological Sample Siting Plan Template (Word) / (PDF)

Routine and Repeat Sampling

Table 64423-A lists the required number of routine samples per month based on population served or number of service connections.  Within 24 hours following a total coliform-positive sample result, water systems shall continue to collect a repeat sample set of 3 samples. All routine and repeat samples must be collected according to the approved bacteriological sample siting plan above.

Level 1 Assessment

If a water system collects... Level 1 Assessment is required within 30 days if...
...Less than 40 routine and repeat samples per month More than 1 TC-positive sample in a month
...40 or more routine and repeat samples per month More than 5.0% TC-positive samples in a month
…a sample that is total coliform positive Fails to collect all required repeat samples

Under the RTCR, a water system which exceeds one of the trigger levels in the table above must conduct a Level 1 Assessment within 30 days. The completed assessment must be submitted to the local regulating agency (DDW District Office or County Health Office) within 30 days of exceeding the trigger level. The Level 1 Assessment will require water systems to identify a possible cause to the total coliform positive samples and corrective actions taken/needed. Failure to conduct or submit a completed assessment, or failure to complete the corrective actions is a violation of the Coliform Treatment Technique in the RTCR.

Templates for the Level 1 Assessment for different types of water systems are available below:

E.coli MCL Exceedances / Level 2 Assessment

E.Coli MCL Exceedances

  1. E.coli-positive repeat sample following TC-positive routine sample
  2. TC-positive repeat sample following an E.coli positive routine sample
  3. Failure to collect all required repeat samples following a E.coli-positive routine sample
  4. Failure to test for E.coli when any repeat sample is TC-positive

Under the RTCR, a water system exceeds the E.coli MCL when any of the four trigger levels above are met. In addition, the State RTCR adds two new conditions to the E.coli MCL for failing to collect all required repeat samples following a E.coli positive routine sample and failing to test for E.coli after a total coliform positive repeat sample. The water system must notify the local regulating agency (DDW District Office or County Environmental Health Office) by the end of the business day to schedule a Level 2 assessment. Similar to the Level 1 assessment, the Level 2 Assessment will require the water system to identify a possible cause to the E.coli positive samples and corrective actions taken/needed. However, the Level 2 Assessment will be performed by the local regulating agency. Failure to return the assessment or complete the corrective actions  is a violation of the Coliform Treatment Technique in the RTCR.

Public notification (Tier 1) will be required within 24 hours of the E.coli MCL exceedance and a template is available.

Seasonal Water Systems

Non-community water systems which do not operate on a year-round basis (e.g. starts-up and shut down at the beginning and end of each operating season) must have an approved, written start-up procedure to comply with the State RTCR requirements. Seasonal water systems are required to follow this start-up procedure which includes:

  1. an inspection of water system components,
  2. disinfection and flushing,
  3. coliform and chlorine residual monitoring,
  4. use of certified distribution operators to perform 1-3 above,
  5. notification to local regulating agency (DDW District Office or Local Primacy Agency, e.g. County Environmental Health Office) upon start-up.

Public Notification

Water systems are required to issue a Tier 1 Public Notice to all customers within 24 hours of learning of an E.coli MCL exceedance.
Water systems are required to issue a Tier 2 Public Notice to all customers within 30 days for the following violations of the Coliform Treatment Technique requirements.

  • Failure to conduct or submit a completed Level 1 or Level 2 Assessment within 30 days of exceeding a coliform treatment technique trigger.
  • Failure to complete any corrective action identified in a Level 1 or Level 2 Assessment by the deadlines given in the assessment
  • For seasonal systems only, failure to complete a State Board-approved start-up procedure prior to serving water to the public.

Templates for these Tier 1 and Tier 2 Public Notices is available on the Templates for Public Notification webpage.

Monthly Coliform Reporting

All water systems are required to report results of coliform monitoring monthly by the 10th day of the following month. A revised monthly summary form and instructions are available below.

  • Monthly Coliform Reporting Form (available by request)
  • Instructions for completing Monthly Coliform Reporting Form (available by request)

Resources

Regulatory Agency Contact Information

Rulemaking History

Pre-Rulemaking Workshops

In February 2017, the State Water Board released a draft of the planned regulation text and held six public workshops throughout California to receive input on the rule. The California version of the RTCR will follow many of the federal requirements, with some exceptions as indicated in the workshops.

Rulemaking Status and Complete Rulemaking Files

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Contact Us

State Water Resources Control Board
Division of Drinking Water
Regulatory Development Unit

Mailing Address:
P.O. Box 100
Sacramento, CA 95812-0100

Street Address:
1001 I Street
Sacramento, CA 95814

E-mail us at DDWRegUnit@waterboards.ca.gov.