Compilation of Rules and Regulations of the State of Georgia
Department 391 - RULES OF GEORGIA DEPARTMENT OF NATURAL RESOURCES
Chapter 391-3 - ENVIRONMENTAL PROTECTION
Subject 391-3-5 - RULES FOR SAFE DRINKING WATER
Rule 391-3-5-.23 - Coliform Sampling

Universal Citation: GA Rules and Regs r 391-3-5-.23

Current through Rules and Regulations filed through September 23, 2024

(1) Routine Coliform Monitoring.

(a) Public water systems must collect total coliform samples at sites which are representative of water throughout the distribution system according to a written sample siting plan. These plans are subject to Division review and revision.

(b) The minimum residential population of a community water system shall be determined by a mathematical calculation of the total number of active residential service connections multiplied by Georgia's average population per household, as published in the most recent Federal Census Bureau Statistics. Multiple residential units served by a single connection (master meter) shall be included in the determination of population for a water system. The minimum monitoring frequency for total coliforms for community water systems is based on the population served by the system, as follows:

Population Served

Minimum Number of Samples per Month

25 to 1,0001

1

1,001 to 2,500

2

2,501 to 3,300

3

3,301 to 4,100

4

4,101 to 4,900

5

4,901 to 5,800

6

5,801 to 6,700

7

6,701 to 7,600

8

7,601 to 8,500

9

8,501 to 12,900

10

12,901 to 17,200

15

17,201 to 21,500

20

21,501 to 25,000

25

25,001 to 33,000

30

33,001 to 41,000

40

41,001 to 50,000

50

50,001 to 59,000

60

59,001 to 70,000

70

70,001 to 83,000

80

83,001 to 96,000

90

96,001 to 130,000

100

130,001 to 220,000

120

220,001 to 320,000

150

320,001 to 450,000

180

450,001 to 600,000

210

600,001 to 780,000

240

780,001 to 970,000

270

970,001 to 1,230,000

300

1,230,001 to 1,520,000

330

1,520,001 to 1,850,000

360

1,850,001 to 2,270,000

390

2,270,001 to 3,020,000

420

3,020,001 to 3,960,000

450

3,960,001 or more

480

1Includes public water systems which have at least 15 service connections, but serve fewer than 25 persons.

If a community water system serving 25 to 1,000 persons has no history of total coliform contamination in its current configuration and a sanitary survey conducted in the past five years shows that the system is supplied solely by a protected ground water source and is free of sanitary defects, the Division may reduce the monitoring frequency specified above, except that in no case shall it be reduced to less than one sample per quarter.

(c) The monitoring frequency for total coliform for non-community water systems is as follows:
1. A non-community water system using only ground water (except ground water under the direct influence of surface water) and serving 1,000 persons or fewer must monitor each calendar quarter that the system provides water to the public, except that the Division may adjust this monitoring frequency in writing, if a sanitary survey shows that the system is free of sanitary defects.

2. A non-community water system using only ground water (except ground water under the direct influence of surface water) and serving more than 1,000 persons during any month must monitor at the same frequency as a like-sized community water system, except that the Division may adjust this monitoring frequency, in writing for any month the system serves 1,000 persons or fewer.

3. A non-community water system using surface water, in total or in part, must monitor at the same frequency as a like-sized community water system, regardless of the number of persons it serves.

4. A non-community water system using ground water under the direct influence of surface water must monitor at the same frequency as a like-sized community water system. The system must begin monitoring at this frequency beginning six months after the Division determines that the ground water is under the direct influence of surface water.

(d) The public water system must collect samples at regular time intervals throughout the month, except that a system which uses only ground water (except ground water under the direct influence of surface water), and serves 4,900 persons or fewer, may collect all required samples on a single day if they are taken from different sites.

(e) Special purpose samples, such as those taken to determine whether disinfection practices are sufficient following pipe placement, replacement, or repair, shall not be used to determine compliance with the MCL for total coliforms. Repeat samples are not considered special purpose samples, and must be used to determine compliance with the MCL for total coliforms.

(2) Repeat Coliform Monitoring.

(a) If a routine sample is total coliform-positive, the public water system must collect a set of repeat samples within 24 hours of being notified of the positive result. A system which collects more than one routine sample per month must collect no fewer than three repeat samples for each total coliform-positive sample found. A system which normally collects one routine sample per month or fewer must collect no fewer than four repeat samples for each total coliform-positive sample found. The Division may extend the 24- hour limit on a case-by-case basis if the system has a logistical problem in collecting the repeat samples within 24 hours that is beyond its control.

(b) The system must collect at least one repeat sample from the sampling tap where the original total coliform-positive sample was taken, and at least one repeat sample at a tap within five service connections upstream and at least one repeat sample at a tap within five service connections downstream of the original sampling site. If a total coliform-­positive sample is at the end of the distribution system, or one away from the end of the distribution system, the Division may waive the requirement to collect at least one repeat sample upstream or downstream of the original sampling site.

(c) The system must collect all repeat samples on the same day, except that the Division may allow a system with a single service connection to collect the required set of repeat samples over a four-day period.

(d) If one or more repeat samples in the set is total coliform-positive, the public water system must collect an additional set of repeat samples in the manner specified in paragraph (2). The additional samples must be collected within 24 hours of being notified of the positive result, unless the Division extends the limit as provided in paragraph (2). The system must repeat this process until either total coliforms are not detected in one complete set of repeat samples or the system determines that the MCL for total coliforms has been exceeded and notifies the Division.

(e) If a system collecting fewer than five routine samples per month has one or more total coliform-positive samples and the Division does not invalidate the sample(s), it must collect at least five routine samples during the next month the system provides water to the public, except that the Division may waive this requirement if the conditions specified below are met. The Division cannot waive the requirement for a system to collect repeat samples.
1. The Division may waive the requirement to collect five routine samples the next month the system provides water to the public if the Division, or an agent approved by the Division, performs a site visit before the end of the next month the system provides water to the public. Although a sanitary survey need not be performed, the site visit must be sufficiently detailed to allow the Division to determine whether additional monitoring and/or any corrective action is needed. The Division cannot approve an employee of the system to perform this site visit, even if the employee is an agent approved by the Division to perform sanitary surveys.

2. The Division may waive the requirement to collect five routine samples the next month the system provides water to the public if the Division has determined why the sample was total coliform-positive and establishes that the system has corrected the problem or will correct the problem before the end of the next month the system serves water to the public. The Division cannot waive the requirement to collect five routine samples the next month the system provides water to the public solely on the grounds that all repeat samples are total coliform-negative. Under this paragraph, a system must still take at least one routine sample before the end of the next month it serves water to the public and use it to determine compliance with the MCL for total coliforms, unless the Division has determined that the system has corrected the contamination problem before the system took the set of repeat samples required above, and all repeat samples were total coliform­-negative.

(f) After a system collects a routine sample and before it learns the results of the analysis of that sample, if it collects another routine sample(s) from within five adjacent service connections of the initial sample, and the initial sample, after analysis, is found to contain total coliforms, then the system may count the subsequent sample(s) as a repeat sample instead of as a routine sample.

(g) Results of all routine and repeat samples not invalidated by the Division must be included in determining compliance with the MCL for total coliforms.

(3) Invalidation of Total Coliform Samples. A total coliform-positive sample invalidated under this paragraph does not count towards meeting the minimum monitoring requirements of this Rule.

(a) The Division may invalidate a total coliform-positive sample only if the conditions that follow below are met:
1. The laboratory establishes that improper sample analysis caused the total coliform-­positive result.

2. The Division, on the basis of the results of repeat samples collected as required by this Rule, determines that the total coliform-positive sample resulted from a domestic or other non-distribution system plumbing problem. The Division cannot invalidate a sample on the basis of repeat sample results unless all repeat sample(s) collected at the same tap as the original total coliform-positive sample are also total coliform-positive, and all repeat samples collected within five service connections of the original tap are total coliform-negative (e.g., the Division cannot invalidate a total coliform-positive sample on the basis of repeat samples if all the repeat samples are total coliform-negative, or if the public water system has only one service connection).

3. The Division has substantial grounds to believe that a total coliform-positive result is due to a circumstance or condition which does not reflect water quality in the distribution system. In this case, the system must still collect all repeat samples required under this Rule, and use them to determine compliance with the MCL for total coliforms. The Division may not invalidate a total coliform-positive sample solely on the grounds that all repeat samples are total coliform-negative.

(b) A laboratory must invalidate a total coliform sample (unless total coliforms are detected) if the sample produces a turbid culture in the absence of gas production using an analytical method where gas formation is examined (e.g., the Multiple-Tube Fermentation Technique), produces a turbid culture in the absence of an acid reaction in the Presence-Absence (P-A) Coliform Test, or exhibits confluent growth or produces colonies too numerous to count with an analytical method using a membrane filter (e.g., Membrane Filter Technique). If a laboratory invalidates a sample because of such interference, the system must collect another sample from the same location as the original sample within 24 hours of being notified of the interference problem, and have it analyzed for the presence of total coliforms. The system must continue to re-sample within 24 hours and have the samples analyzed until it obtains a valid result. The Division may waive the 24-hour time limit on a case-by-case basis.

(4) Sanitary Surveys.

(a) All ground water systems must undergo sanitary surveys no less frequently than every three years for community systems, except as provided in paragraph (4)(b), and no less frequently than every five years for non-community systems. The initial sanitary survey for each community ground water system must be conducted by December 31, 2012, unless the system meets requirements of paragraph (4)(b).

(b) For community ground water systems determined by the Division to have outstanding performance based on prior sanitary surveys, or that provide at least 4-log (99.99%) treatment of viruses (using inactivation, removal, or a combination of the two) subsequent sanitary surveys may be conducted no less than every five years. The initial sanitary survey for community systems that meet these requirements and for each non-community system must be conducted by December 31, 2014.

(c) All surface water systems (including ground water under the influence) must undergo sanitary surveys no less frequently than every three years for community systems and no less frequently than every five years for non-community systems. For community systems determined by the Division to have outstanding performance based on prior sanitary surveys, subsequent sanitary surveys may be conducted no less than every five years.

(d) Sanitary surveys must be performed by the Division or an agent approved by the Division. The system is responsible for ensuring the survey takes place.

(5) Fecal Coliforms - Escherichia coli (E. coli) Testing.

(a) If any routine or repeat sample is total coliform-positive, the system must analyze that total coliform-positive culture medium to determine if fecal coliforms are present, except that the system may test for E. coli in lieu of fecal coliforms. If fecal coliforms or E. coli are present, the system must notify the Division by the end of the day when the system is notified of the test result, unless the system is notified of the result after the Division office is closed, in which case the system must notify the Division before the end of the next business day.

(b) The Division has the discretion to allow a public water system, on a case-by-case basis, to forego fecal coliform or E. coli testing on a total coliform-positive sample if that system assumes that the total coliform-positive sample is fecal coliform-positive or E. coli-positive. Accordingly, the system must notify the Division as specified in this Rule and the MCL applies.

(6) Analytical Methodology.

(a) The standard sample volume required for total coliform analysis, regardless of analytical method used, is 100 mL.

(b) Public water systems need only determine the presence or absence of total coliforms; a determination of total coliform density is not required.

(c) Public water systems must conduct total coliform analyses in accordance with 40 CFR § 141.21.

(d) Public water systems must conduct fecal coliform analyses in accordance with 40 CFR § 141.21.

(7) Response to Violation.

(a) A public water system which has exceeded the MCL for total coliforms must report the violation to the Division no later than the end of the next business day after it learns of the violation, and notify the public in accordance with this chapter.

(b) A public water system which has failed to comply with a coliform monitoring requirement, including the sanitary survey requirement, must report the monitoring violation to the Division within ten days after the system discovers the violation, and notify the public in accordance with this chapter.

(8) The provisions of paragraphs (1) and (4) are applicable until March 31, 2016. The provisions of paragraphs (2), (3), (5), (6), and (7) are applicable until all required repeat monitoring under paragraph (2) and fecal coliform or E. coli testing under paragraph (5) that was initiated by a total coliform-positive sample taken before April 1, 2016 is completed, as well as analytical method, reporting, recordkeeping, public notification, and consumer confidence report requirements associated with that monitoring and testing. Beginning April 1, 2016, the provisions of Rule 391-3-5-.55 are applicable, with systems required to begin regular monitoring at the same frequency as the system-specific frequency required on March 31, 2016, except for seasonal systems which must monitor monthly beginning April 1, 2016.

O.C.G.A. § 12-5-170 et seq.

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