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Total Coliform Rule

The Total Coliform Rule requires all public water systems to monitor water in the distribution system for the presence of total coliform.

The Total Coliform Rule (TCR) was enacted by the Environmental Protection Agency (EPA) in 1990. The rule sets both health goals and legal limits for the presence of total coliform in drinking water. Every public water system (PWS) is required to monitor for the presence of coliform bacteria to protect customers from waterborne illness. The specific monitoring requirements for your system are based on the number of customers you serve and the type of system you operate.

Questions and Answers

What is the purpose?

Monitoring for the presence of microbes, specifically for coliform bacteria, is a method to determine whether the water in the distribution system of a PWS is contaminated with a variety of bacteria, parasites, and viruses which can cause health problems when humans ingest them. Testing water for each of these pathogens separately would be difficult and expensive. Instead, water systems must measure coliform levels. The presence of any coliform in drinking water suggests that there may be disease-causing agents in the water.
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Does this rule address private water systems? If not, how does the TCEQ help protect them?

This rule does not address private water systems because they are not under the jurisdiction of the Safe Drinking Water Act and are therefore not subject to TCEQ regulation. The TCEQ has provided outreach material to homeowners to help them understand how to manage their systems. The TCEQ recommends that private water system owners periodically test their water for microbial and chemical contaminants and properly maintain their system. More information is available on the EPA's Private Wells Web site.Exit the TCEQ
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What are the basic requirements of the Total Coliform Rule?

The risk-targeting strategy incorporated into the rule provides for:

  • monthly bacteriological testing
  • repeat sampling when a routine sample result is coliform positive, and, in the case of groundwater systems, triggered source monitoring (Ground Water Rule)
  • increased monitoring for smaller PWS (those that take fewer than five monthly samples) on the month following a total coliform positive sample result
  • public notices posted to inform customers following any Total Coliform Rule violation

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What are the monitoring provisions?

Total coliform samples must be collected at sites which are representative of water quality throughout the distribution system according to a written sample monitoring plan. More information on creating a monitoring plan is available in the TCEQ's manual, How to Develop a Monitoring Plan.

Samples must be collected at regular time intervals throughout the month, except for groundwater systems serving 4,900 persons or fewer may collect them on the same day. Following sample collection, samples must be immediately taken to a TCEQ-certified testing lab. Monthly sampling requirements are based on population served (see table below for the minimum sampling frequency).

ROUTINE Monitoring Frequencies for Public Water Systems

Note: If your PWS serves fewer than 25 people but has at least 15 service connections, you must take at least one routine monitoring sample each month.

Other PWSs:

  • Serving 25–25,000 people, see Table 1
  • Serving 25,001–450,000 people, see Table 2
  • Serving more than 450,000 people, see Table 3

Table 1. PWSs serving 25–25,000 people
If your PWS serves
this many people:
Take at least
this many samples each month:
25-1,000 1
1,001-2,500 2
2,501-3,300 3
3,301-4,100 4
4,101-4,900 5
4,901-5,800 6
5,801-6,700 7
6,701-7,600 8
7,601-8,500 9
8,501-12,900 10
12,901-17,200 15
17,201-21,500 20
21,501-25,000 25

 

Table 2. PWSs serving 25,001–450,000 people
If your PWS serves
this many people:
Take at least
this many samples each month:
25,001-33,000 30
33,001-41,000 40
41,001-50,000 50
50,001-59,000 60
59,001-70,000 70
70,001-83,000 80
83,001-96,000 90
96,000-130,000 100
130,001-220,000 120
220,001-320,000 150
320,001-450,000 180

 

Table 3. PWSs serving more than 450,001 people
If your PWS serves
this many people:
Take at least
this many samples each month:
450,001-600,000 210
 600,001-780,000 240
 780,001-970,000 270
 970,001-1,230,000 300
 1,230,001-1,520,000 330
 1,520,001-1,850,000 360
 1,850,001-2,270,000 390
 2,270,001-3,020,000 420
 3,020,001-3,960,000 450
 over 3,960,000 480

Each total coliform–positive ROUTINE sample must be tested for the presence of fecal coliforms or E. coli. If any ROUTINE sample is total coliform–positive, REPEAT samples are required.

REPEAT Sampling Requirements

Within 24 hours of learning of a total coliform–positive 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 tap as the original sample.
  • One REPEAT sample must be collected within five service connections upstream.
  • One REPEAT sample must be collected within five service connections downstream.
  • Systems that collect only one ROUTINE sample per month must collect a 4th REPEAT sample within five service connections in either direction of the original sample tap.

If any REPEAT sample is total coliform–positive:

  • The system must analyze that total coliform–positive culture for fecal coliform or E. coli.
  • The system must collect another set of REPEAT samples, as before, unless the Maximum Contaminant Level (MCL) for coliform has been reached and the system has notified the state.

Additional sample requirements in the event of a coliform positive ROUTINE sample:

  • If your PWS is a groundwater system, you may need to also take RAW samples from each of your wells and/or contact your groundwater wholesaler/purchaser. For more information on RAW sample and reporting requirements, please visit the Ground Water Rule webpage.
  • A positive ROUTINE or REPEAT total coliform result requires a minimum of five ROUTINE samples to be collected the following month. If the PWS regularly takes five or more samples per month, no change in sampling is necessary.

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Where can I find a certified lab to take my samples?

Samples must be delivered to a laboratory accredited by the State of Texas under the National Environmental Accreditation Program (NELAP) within 24 hours of collection. A complete list of NELAP certified labs can be found here.

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What violations are associated with the Total Coliform Rule?

There are several violations that can be committed under the the Total Coliform Rule:

  • failure to collect any or all ROUTINE samples for each month
  • failure to collect any or all REPEAT samples following a ROUTINE coliform positive sample
  • failure to collect any or all increased monitoring ROUTINE samples the month following a coliform positive sample
  • reaching the MCL during any one month
  • reaching an Acute MCL during any one month.

A Monthly MCL violation is triggered if:

  • a system collecting fewer than 40 samples per month has greater than one ROUTINE/REPEAT sample per month which is total coliform–positive.
  • a system collecting at least 40 samples per month has a greater than 5.0 percent of the ROUTINE/REPEAT samples in a month total coliform–positive

An Acute MCL violation is triggered if:

  • any public water system has any fecal coliform– or E. coli–positive REPEAT sample result
  • a fecal coliform– or E. coli–positive ROUTINE sample is followed by a total coliform–positive REPEAT sample result

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What are the Public Notification and Reporting Requirements?

For a Monthly MCL Violation:

  • The violation must be reported to the TCEQ no later than the end of the next business day after the system learns of the violation.
  • The public must be notified within 30 days after the system learns of the violation.

For an Acute MCL violation:

  • The violation must be reported to the TCEQ no later than end of the next business day after the system learns of the violation.
  • The public must be notified within 24 hours after the the system learns of the violation.
  • Systems with ROUTINE or REPEAT samples that are fecal coliform– or E. coli–positive must notify the TCEQ by the end of the day they are notified of the result or by the end of the next business day if the TCEQ office is already closed.

For more information on public notices, including the mandatory language and certificate of delivery forms, please visit the Public Notice Web page.

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Where can I access more documents related to the Total Coliform Rule?

The following links are to other forms associated with the Total Coliform Rule:

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