PURPOSE: This rule establishes maximum contaminant levels and monitoring requirements for microbiological contaminants. (1) Routine Monitoring.

1. (A) Public water systems must collect total coliform samples according to a written sample siting plan at sites which are representative of water throughout the distribution system. This plan shall be made available to the inspector conducting a sanitary survey or onsite inspection, or to the department upon request and the department will either approve or recommend improvements.

   1. 1. All routine samples should be taken

from the distribution system.

1. 2. Distribution sampling points should

be chosen where both upstream and downstream repeat samples can be taken within five (5) service connections of the principal sampling point. The same distribution points may be used each month, but there must be a separate point for each distribution sample collected each day.

1. 3. Groundwater supplies collecting five

1. (5) or fewer samples per month may collect all samples on the same day with departmental approval; provided, that the samples are all collected from different points. Other supplies shall collect samples at regular intervals throughout the month.

   1. 4. Groundwater supplies under the

direct influence of surface water that do not practice filtration must identify a sample point near the first service connection which is one (1) of twenty percent (20%) of all service connections in the entire system that are nearest the water supply treatment facility as measured by water transport time within the distribution system.

1. 5. Supplies should identify at least five

1. (5) sampling taps since these are needed for five (5) routine samples in the month following an unsafe sample.

   1. (B) The monitoring frequency for total coliforms for community water systems is based on the population served by the system as follows except that systems utilizing surface or ground water under the direct influence of surface water and systems practicing iron removal or lime softening must collect at least five (5) samples per month. In addition, the department may require a greater frequency if necessary:

Total Coliform Monitoring Frequency for Community Water Systems

Minimum Samples

Population Served Per Month 25—1000* 1 1001—2500 2 2501—3300 3 3301—4100 4 Minimum Samples Population Served Per Month 4101—4900 4901—5800 5801—6700 6701—7600 7601—8500 8501—12,900 12,901—17,200 17,201—21,500 21,501—25,000 25,001—33,000 33,001—41,000 41,001—50,000 50,001—59,000 59,001—70,000 70,001—83,000 83,001—96,000 96,001—130,000 130,001—220,000 220,001—320,000 320,001—450,000 450,001—600,000 600,001—780,000 780,001—970,000 970,001—1,230,000 1,230,001—1,520,000 1,520,001—1,850,000 1,850,001—2,270,000 2,270,001—3,020,000 3,020,001—3,960,000 3,960,001—more *Includes public water systems which have at least fifteen (15) service connections but serve fewer than twenty-five (25) persons. (C) The monitoring frequency for total coliforms for noncommunity water systems is as follows, except that the department may require a greater frequency:

1. 1. A noncommunity water system using

only groundwater (except groundwater under the direct influence of surface water) and serving one thousand (1,000) persons or fewer per day must monitor each calendar quarter that the system provides water to the public, except that the department may reduce this monitoring frequency, in writing, if a sanitary survey or on-site inspection shows that the system is free of sanitary defects. Beginning June 29, 1994, the department cannot reduce the monitoring frequency for a noncommunity water system using only groundwater (except groundwater under the direct influence of surface water) and serving one thousand (1,000) persons or fewer per day to less than once per year;

1. 2. A noncommunity water system using

only groundwater (except groundwater under the direct influence of surface water) and serving more than one thousand (1,000) persons per day during any month must monitor at the same frequency as a like-sized community water system, as specified in subsection (1)(B) of this rule, except that the department may reduce this monitoring frequency, in writing, for any month the system serves less than one thousand (<1,000) persons per day. The department cannot reduce the monitoring frequency to less than once per year. For systems using groundwater under the direct influence of surface water, paragraph (1)(C)4. of this rule applies;

1. 3. A noncommunity water system using

surface water, in total or in part, must monitor at the same frequency as a like-sized community water system that uses surface water, as specified in subsection (1)(B) of this rule; and

1. 4. A noncommunity water system using

groundwater under the direct influence of surface water must monitor at the same frequency as a like-sized community water system that uses surface water, as specified in subsection (1)(B) of this rule. The system must begin monitoring at this frequency beginning six (6) months after the department determines that the groundwater is under the direct influence of surface water.

1. (D) The public water system must collect samples at regular time intervals throughout the monitoring period, except that a system which uses groundwater (except groundwater under the direct influence of surface water) and serves four thousand nine hundred (4,900) persons or fewer, may collect, with departmental approval, all samples on a single day if they are taken from different sites.
2. (E) A public water system that uses groundwater under the direct influence of surface water and does not practice filtration must collect at least one (1) sample near the first service connection each day the turbidity level of the source water, measured as specified in 10 CSR 60-5.010(1), exceeds one

1. (1) nephelometric turbidity unit (NTU). This sample must be analyzed for the presence of total coliforms. When one (1) or more turbidity measurements in any day exceeds one
2. (1) NTU, the system must collect this coliform sample within twenty-four (24) hours of the exceedance unless the department determines that the system, for logistical reasons outside its control, cannot have the sample analyzed within thirty (30) hours of collection. Sample results from this coliform monitoring must be included in determining compliance with the maximum contaminant levels (MCLs) for total coliforms in section

3. (7) of this rule.

   1. (F) 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 in section (7) of this rule. Repeat samples taken pursuant to section (2) of this rule are not considered special purpose samples and must be used to determine compliance with the MCL for total coliforms in section (7) of this rule.

4. (2) Repeat Monitoring.

   1. (A) If a routine sample is total coliformpositive, the public water system must collect a set of repeat samples within twenty-four

5. (24) hours of being notified of the positive result. The department may extend the twenty-four (24)-hour limit on a case-by-case basis if the system has a logistical problem in collecting repeat samples that is beyond its control. In the case of an extension, the department must specify how much time the system has to collect the repeat samples. A system which collects more than one (1) routine sample per month must collect no fewer than three (3) repeat samples for each total coliform-positive sample found. A system which collects one (1) routine sample per month or fewer must collect no fewer than four (4) repeat samples for each total coliform-positive sample found.

   1. (B) The system must collect at least one (1) repeat sample from the sampling tap where the original total coliform-positive sample was taken and at least one (1) repeat sample at a tap within five (5) service connections upstream and at least one (1) repeat sample at a tap within five (5) service connections downstream of the original sampling site. If a total coliform-positive sample is at the end of the distribution system, or one (1) away from the end of the distribution system, the department may waive the requirement to collect at least one (1) repeat sample upstream or downstream of the original sampling site except that the total number of repeat samples shall not be reduced.
   2. (C) The system must collect all repeat samples on the same day, except that the department may allow a system with a single service connection to collect the required set of repeat samples over a four (4)-day period or to collect a larger volume repeat sample(s) in one (1) or more sample containers of any size, as long as the total volume collected is at least four hundred milliliters (400 ml) (three hundred milliliters (300 ml) for systems which collect more than one (1) routine sample per month). Systems with more than one (1) service connection, but fewer service connections than the required number of repeat samples, shall collect repeat samples as directed by the department.
   3. (D) If one (1) 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 subsections (2)(A)–(C) of this rule. The additional samples must be collected within twenty-four (24) hours of being notified of the positive result, unless the department extends the limit as provided in subsection (2)(A) of this rule. The system must repeat this process until either total coliforms are not detected in one (1) complete set of repeat samples or the system determines that the MCL for total coliforms in section (7) of this rule has been exceeded and notifies the department.
   4. (E) If a system collecting fewer than five

6. (5) routine samples per month has one (1) or more total coliform-positive samples and the department does not invalidate the sample(s) under section (3) of this rule, it must collect at least five (5) routine samples during the next month the system provides water to the public, except that the department may waive this requirement if the following conditions are met (the department cannot waive the requirement for a system to collect repeat samples in subsections (2)(A)–(D) of this rule):

   1. 1. The department may waive the

requirement to collect five (5) routine samples the next month the system provides water to the public if the department, or an agent approved by the department, 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 department to determine whether additional monitoring, any corrective action, or both, is needed. The department cannot approve an employee of the system to perform this site visit, even if the employee is an agent approved by the department to perform sanitary surveys; and

1. 2. The department may waive the

requirement to collect five (5) routine samples the next month the system provides water to the public if the department has determined why the sample was total coliformpositive 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. In this case, the department must document this decision to waive the following month’s additional monitoring requirement in writing, have it approved and signed by the supervisor of the department official who recommends the decision, and make this document available to the Environmental Protection Agency (EPA) and the public upon request. The written documentation must describe the specific cause of the total coliform-positive sample and what action the system has taken, or will take, to correct this problem. The department 10 CSR 60-4

cannot waive the requirement to collect five (5) 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 (1) 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 in section (7) of this rule, unless the department has determined that the system has corrected the contamination problem before the system took the set of repeat samples required in subsections (2)(A)–(D) of this rule and all repeat samples were total coliform-negative.

1. (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 (5) 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.
2. (G) Results of all routine and repeat samples not invalidated by the department must be included in determining compliance with the MCL for total coliforms in section (7) of this rule.

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

   1. (A) The department may invalidate a total coliform-positive sample only if any one (1) of the following conditions is met:

      1. 1. The laboratory establishes that

improper sample analysis caused the total coliform-positive result;

1. 2. The department, on the basis of the

results of repeat samples collected as required by subsections (2)(A)–(D) of this rule, determines that the total coliform-positive sample resulted from a domestic or other nondistribution system plumbing problem. The department cannot invalidate a sample on the basis of repeat sample results unless all repeat samples collected at the same tap as the original total coliform-positive sample are also total coliform-positive, and all repeat samples collected within five (5) service connections of the original tap are total coliform-negative (that is, the department 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 (1) service connection); or

1. 3. The department 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 in subsections (2)(A)–(D) of this rule and then use them to determine compliance with the MCL for total coliforms in section (7) of this rule. To invalidate a total coliform-positive sample under this section, the decision with the rationale for the decision must be documented in writing, and approved and signed by the supervisor of the department official who recommended the decision. The department must make this document available to the EPA and to the public upon request. The written documentation must state the specific cause of the total coliformpositive sample and what action the system has taken, or will take, to correct this problem. The department may not invalidate a total coliform-positive sample solely on the grounds that all repeat samples are total coliform-negative.

1. (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 (that is, the multiple-tube fermentation (MTF) 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 (that is, membrane filter technique (MFT)). When a laboratory invalidates a sample because of this interference, the system must collect another sample from the same location as the original sample within twenty-four (24) hours of being notified of the invalidation and have it analyzed for the presence of total coliform. The system must continue to resample within twenty-four (24) hours and have the samples analyzed until it obtains a valid result. The department may extend the twenty-four (24)- hour limit on a case-by-case basis if the system has a logistical problem in collecting the sample that is beyond its control. In the case of an extension, the department must specify how much time the system has to collect the replacement samples.

1. (4) Sanitary Surveys.

   1. (A) Public water systems which do not collect five (5) or more routine samples per month must undergo an initial sanitary survey or on-site inspection by June 29, 1994, for community public water systems and June 29, 1999, for noncommunity water systems. After that, systems must undergo another sanitary survey or on-site inspection every five (5) years, except that noncommunity water systems using only protected and disinfected groundwater, as defined by the department, must undergo subsequent sanitary surveys or on-site inspections at least every ten (10) years after the initial sanitary survey or on-site inspection. The department must review the results of each sanitary survey or on-site inspection to determine whether the existing monitoring frequency is adequate and what additional measure, if any, the system needs to undertake to improve drinking water quality.
   2. (B) Sanitary surveys or on-site inspections must be performed by the department or an agent approved by the department. The system is responsible for ensuring that the sanitary survey or on-site inspection takes place. Agents that can be approved by the department to conduct sanitary surveys include engineers. Agents that can be approved by the department to conduct on-site inspections include, but are not limited to, sanitarians and environmental specialists from other state agencies acting in their official capacity. Reports of sanitary surveys and on-site inspections shall include completed forms approved by the department. Sanitary surveys and on-site inspections shall be done in accordance with criteria established by the department.

2. (5) Fecal Coliforms/Escherichia coli (E. coli) Testing.

   1. (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

3. E. coli are present, the system must notify the department by the end of the day when the system is notified of the result, unless the system is notified of the result after the department office is closed, in which case the system must notify the department before the end of the next business day.

   1. (B) The department has the discretion to allow a public water system, on a case-bycase basis, to forego fecal coliform or E. coli testing on a total coliform-positive sample if that system assumes that the total coliformpositive sample is fecal coliform-positive or

4. E. coli-positive. The system must notify the department as specified in subsection (5)(A) of this rule, except as provided in subsection (5)(C) of this rule, and must provide Tier 1 notice to the public as specified in 10 CSR 60-8.010, including the mandatory health effects language for fecal coliform/E.coli.

   1. (C) The department, after consideration of the circumstances surrounding a specific incident, may reduce or extend the public notice period for acute violations, as it deems appropriate.

5. (6) Response to Violation.

   1. (A) A public water system which has exceeded the MCL for total coliforms in section (7) of this rule must report the violation to the department no later than the end of the next business day after it learns of the violation and notify the public in accordance with 10 CSR 60-8.010.
   2. (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 department within ten (10) days after the system discovers the violation and notify the public in accordance with the applicable requirement in 10 CSR 60-8.010.

6. (7) Maximum Contaminant Levels (MCL) for Microbiological Contaminants.

   1. (A) Until March 31, 2016, the total coliform MCL is based on the presence or absence of total coliforms in a sample, rather than coliform density. Public water systems need only determine the presence or absence of total coliforms; a determination of total coliform density is not required.

      1. 1. For a system which collects at least

forty (40) samples per month, if no more than five percent (5.0%) of the samples collected during a month are total coliform-positive, the system is in compliance with the MCL for total coliforms.

1. 2. For a system which collects fewer than

forty (40) samples per month, if no more than one (1) sample collected during a month is total coliform-positive, the system is in compliance with the MCL for total coliforms.

1. (B) Until March 31, 2016, any fecal coliform-positive repeat sample or E. coli-positive repeat sample, or any total coliform-positive repeat sample following a fecal coliform-positive or E. coli-positive routine sample constitutes a violation of the MCL for total coliforms. For purposes of the public notification requirements in 10 CSR 60- 8.010, this is a violation that may pose an acute risk to health.
2. (C) Beginning April 1, 2016, a system is in compliance with the MCL for E. coli for samples taken under the provisions of 10 CSR 60-4.022 of this section unless any of the conditions identified in paragraphs (7)(C)1. through (7)(C)4. of this rule occur. For purposes of the public notification requirements in 10 CSR 60-8.010, violation of the MCL for

1. E. coli may pose an acute risk to health.

   1. 1. The system has an E. coli-positive

repeat sample following a total coliform-positive routine sample.

1. 2. The system has a total coliform-posi-

tive repeat sample following an E. coli-positive routine sample.

1. 3. The system fails to take all required

repeat samples following an E. coli-positive routine sample.

1. 4. The system fails to test for E. coli

when any repeat sample tests positive for total coliform.

1. (D) Until March 31, 2016, a public water system must determine compliance with the MCL for total coliforms in subsections (7)(A) and (B) of this rule for each month in which it is required to monitor for total coliforms. Beginning April 1, 2016, a public water system must determine compliance with the MCL in subsection (7)(C) of this rule for each month in which it is required to monitor for total coliforms.

1. (8) Coliform sampling. The provisions of sections (1) and (4) of this rule are applicable until March 31, 2016. The provisions of sections (2), (3), (5), and (6) of this rule and 10 CSR 60-5.010(3) are applicable until all required repeat monitoring under section (2) of this rule and fecal coliform or E. coli testing under section (5) of this rule 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 on April 1, 2016, the provisions of 10 CSR 60-4.022 are applicable, with systems required to begin regular monitoring at the same frequency as the system-specified frequency required on March 31, 2016.

AUTHORITY: section 640.100, RSMo Supp. 2014.* Original rule filed May 4, 1979, effective Sept. 14, 1979. Amended: Filed April 14, 1981, effective Oct. 11, 1981. Rescinded and readopted: Filed Dec. 4, 1990, effective July 8, 1991. Amended: Filed Feb. 1, 1996, effective Oct. 30, 1996. Amended: Filed March 17, 2003, effective Nov. 30, 2003. Amended: Filed Aug. 12, 2015, effective March 30, 2016. *Original authority: 640.100, RSMo 1939, amended 1978, 1981, 1982, 1988, 1989, 1992, 1993, 1995, 1996, 1998, 1999, 2002, 2006, 2012, 2014.