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Water Quality Division > Programs > Public Water Supply > Revised Total Coliform Rule
Revised Total Coliform Rule
The Revised Total Coliform Rule applies to all Public Water Supplies

What is the Revised Total Coliform Rule?

On April 1, 2016, the Oklahoma Department of Environmental Quality will begin implementing provisions of the Environmental Protection Agency’s Revised Total Coliform Rule.  The Revised Total Coliform Rule replaces the existing Total Coliform Rule.  The purpose of the Revised Total Coliform Rule (RTCR) is to increase public health protection through the reduction of potential pathways for microbial contamination to enter distribution systems and to better protect the public from waterborne illness.
 
The most notable changes are that the Revised Total Coliform Rule establishes a maximum contaminant level (MCL) for E. coli and adopts a “find and fix” approach to address potential pathways of contamination that could result in bacteriological contamination in the water system.  It requires PWSs to perform assessments to identify sanitary defects in the water system and to take action to correct any defects that are found.

Other notable changes are as follows:

  • Reducing the number of repeat samples from four to three
  • Increasing monitoring from quarterly to monthly at seasonally-operated water systems that are depressurized for the off-season or that have areas that are restricted to the public during the off-season
  • Altering the requirement for additional routine samples the month after a total coliform positive sample is collected
    • For PWSs that monitor monthly, no additional samples will be required for the month following a total coliform positive sample
    • For PWSs that monitor quarterly, the number of additional samples the month following a total coliform positive sample will be reduced from five to three samples
  • Monitoring will be increased from quarterly to monthly for non-community and non-transient non-community PWSs after exceeding the E. coli MCL, when multiple assessments have been triggered, or after other certain violations.

The Revised Total Coliform Rule works in conjunction with the existing Ground Water Rule. Therefore, the coliform monitoring revisions under the RTCR do not change the triggered monitoring at groundwater sources required by the Ground Water Rule for all water systems serving groundwater.  

What should every PWS accomplish by April 1, 2016 to prepare for the Revised Total Coliform Rule?

  • PWSs must develop a DEQ approved Revised Total Coliform Rule sample site plan (based on population) that identifies the system’s sample collection schedule and all routine sample sites. Revised Total Coliform Rule Sample Site Form for Community PWS (PDF, DOCX) or Revised Total Coliform Rule Sample Site Form for Non-Community PWS (PDF, DOCX).
  • PWSs monitoring quarterly should try to identify at least three routine sample sites in their sample site plan, although more routine sample sites may be needed to adequately represent the distribution system.
  • Sample site plans must be reviewed and approved by DEQ.


What are the Major Provisions of the Revised Total Coliform Rule?

Routine Monitoring Requirements:

  • Total coliform samples must be collected by PWSs at sites which are representative of water quality throughout the distribution system according to the DEQ approved sample site plan.
  • The number of routine total coliform samples required for community PWSs serving more than 1000 people remains the same as in the original Total Coliform Rule.
  • Non-community PWSs on a quarterly monitoring schedule that do not maintain compliance with RTCR will be placed on an increased monthly monitoring schedule.
  • For PWSs collecting more than one sample per month, total coliform samples must be collected at regular intervals throughout the month.
    • An exception is that ground water systems serving 4,900 or fewer people may collect all required samples on a single day, if the samples are taken from different sample sites.
  • 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 DEQ immediately. During normal business hours call 1-405-702-8100. After hours, on weekends, and on holidays call 1-800-522-0206.
  • If any routine sample is TC+, then three repeat samples are required.
  • PWSs on quarterly monitoring must take at least three routine samples during the month following a TC+ routine or repeat sample.

Repeat Monitoring Requirements

 

Repeat Monitoring

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 repeat sample must be collected from the same sample site as the original sample.
  • One repeat sample must be collected from within five service connections upstream of the original sample site.
  • One repeat sample must be collected from within five service connections downstream of the original sample site.

If one or more repeat samples 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 DEQ immediately.
  • The PWS must collect another set of three repeat samples using the same sample sites as the first set of repeat samples.

 

Assessments and Corrective Actions

The Revised Total Coliform Rule requires PWSs that have an indication of coliform contamination to assess the PWS and take corrective actions. Indicators of coliform contamination include a failure to monitor for total coliform, TC+ sample results, and an E. coli MCL violation.  The type of assessment conducted (Level 1 or Level 2) is based on the severity or frequency of the problem.

Assessments and Corrective Actions

Level 1 and Level 2 Assessments

The purpose of both Level 1 and Level 2 Assessments is to “find and fix” sanitary defects at the PWS including:

  • Sanitary defects that could provide a pathway of entry for microbial contamination, or
  • Sanitary defects that indicate a potential or existing failure of protective barriers against microbial contamination.

Guidance on how to conduct Level 1 and Level 2 Assessments and how to correct sanitary defects found during the Assessments can be found at: Revised Total Coliform Rule Assessments and Corrective Actions Guidance Manual

Corrective Actions

When sanitary defects are identified during a Level 1 or Level 2 Assessment, they should be corrected as soon as possible to protect public health. 

The PWS must complete all corrective actions by one of the following timeframes:

  • Before the assessment form is submitted to DEQ, which must be within 30 days of triggering the assessment, or
  • According to a DEQ-approved schedule proposed in the assessment form.

Level 1 Assessments (Level 1 Assessments Form)

Level 1 Assessment Triggers

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

  • Two or more TC+ samples in the same month (for PWSs collecting less than 40 samples per month)
  • At least 5% of samples are TC+ in the same month (for PWSs collecting at least 40 samples per month)
  • A PWS fails to collect all required repeat samples after a TC+ sample

Conducting Level 1 Assessments

  • Level 1 Assessments must be performed by the PWS owner or operator each time a Level 1 Assessment is triggered.  PWSs may utilize assistance from any of the following to conduct Level 1 Assessments: DEQ, a certified operator, a consultant, a licensed plumber, a licensed well driller, or an Oklahoma Rural Water Association circuit rider.
  • The PWS must submit the completed Level 1 Assessment form to DEQ within 30 days of the trigger to perform the assessment.

Level 2 Assessments (Level 2 Assessments Form)

Level 2 Assessment Triggers

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

  • A PWS incurs an E. coli MCL violation
  • A PWS has a second Level 1 Assessment triggered within a rolling 12-month period

Conducting Level 2 Assessments

  • Level 2 Assessments triggered by an E. coli MCL violation must be performed by qualified DEQ staff.
  • Level 2 Assessments triggered by a second Level 1 Assessment in a rolling 12-month period may only be conducted by (1) qualified DEQ staff, (2) a current Class A waterworks certified operator or a certified operator with at least a level of certification higher than required for the PWS being assessed, (3) an Oklahoma Rural Water Association circuit rider, or (4) a consulting professional engineer. 
  • The PWS must submit the completed Level 2 Assessment form to DEQ within 30 days of the trigger to perform the assessment.


Seasonal System Provisions

The Revised Total Coliform Rule defines seasonal systems and specifies additional requirements for these types of PWSs:

  • A seasonal system is defined as a non-community PWS that does not operate year round, such as having a depressurized distribution system for any part of the year or when public access is restricted for a period of at least 60 consecutive days. 
  • A seasonal system starts up and shuts down at the beginning and end of each operating season.
  • At the beginning of each operating season, before serving water to the public, seasonal water systems must accomplish the following:

Start-Up Procedure and Monthly Monitoring for Seasonal Systems

Start-up Procedure for Seasonal Systems

The DEQ-approved start-up procedure for seasonal systems, which must be completed prior to serving water to the public, includes:

  1. Inspect and repair your water system before you deliver water to your customers.  Some parts of your water system may have broken down or become worn out during the off-season.
  2. Flush all pipes and drain storage tanks to remove buildup and dirty water that gathered during the off-season.  Inspect drained storage tanks and clean all interior surfaces of the tanks if gunk or build up is visible.
  3. Disinfect pipes and storage tanks by filling them with disinfected water and ensure the disinfected water is present in all areas of your water pipes.  After allowing the disinfected water to remain in the pipes for at least 24 hours, flush the system again. Refer to DEQ’s “Disinfection of Individual Water Wells” factsheet.
  4. Refill all pipes and storage tanks with new fresh water.
  5. Collect at least one sample that is absent of coliforms (safe or negative) daily for two consecutive days. 

The start-up procedure must be completed and the start-up certification form, including TC- sample results, must be submitted to DEQ before serving water to the public.

Routine Monitoring for Seasonal Systems

All seasonal PWSs must monitor monthly for the entire season that the PWS serves water to the public.

 

Major Violations of the Revised Total Coliform Rule

E. coli MCL Violations

A PWS will receive an E. coli MCL Violation when any of these Routine/Repeat sample combinations occur:

Routine/Repeat Sample Combinations

Routine Sample Result:

Repeat Sample Status:

EC+

TC+

EC+

EC+

EC+

 Any missing repeat sample

TC+

EC+

TC+

TC+ (but no E. coli analysis)

Treatment Technique Violations

A PWS will receive a treatment technique violation when any of these 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 a DEQ-approved schedule.
  • Failure of a seasonal system to complete the DEQ-approved start-up procedures prior to serving water to the public.

Key Points for Public Water Systems to Remember
Find and fix sanitary defects as soon as you become aware of them.

    • This can help reduce E. coli MCL violations, which trigger a Level 2 Assessment.
    • This can help reduce TC+ sample results, which may trigger a Level 1 Assessment.

Be sure to collect all routine and repeat samples as required.

    • Timely and correct monitoring can prevent triggering a Level 1 or Level 2 Assessment because:
      • A failure to conduct repeat monitoring automatically triggers an assessment.
      • A Level 1 Assessment triggered twice within a certain timeframe triggers a Level 2 Assessment.

For questions about the Revised Total Coliform Rule, please contact Michele Welsh

Additional Resources