Part 5, Subpart 5-1 Public Water Systems

If the results of a monitoring sample analysis exceed the MCL, the supplier of water shall collect one more sample from the same sampling point within 2 weeks or as soon as practical.

An MCL violation for all contaminants listed in this table, except for Arsenic, occurs when the average¹ of the initial sample and any confirmation sample exceeds the MCL.

MCL violations for Arsenic will be determined as follows:

Compliance with the Arsenic MCL shall be determined based on the analytical result(s) obtained at each sampling point.

For systems which are conducting monitoring at a frequency greater than annual, an Arsenic MCL violation occurs when the running annual average^7,8,9 at any sampling point is greater than the MCL. If any one sample would cause the annual average to exceed the MCL at any sampling point, the system is out of compliance with the MCL immediately.

Systems monitoring annually or less frequently whose sample result exceeds the Arsenic MCL⁷ must begin quarterly sampling¹⁰. The system will not be considered in violation of the MCL until it has completed one year of quarterly sampling and the running annual average^7,8,9 at that sampling point is greater than the Arsenic MCL. If any one sample would cause the annual average to exceed the MCL at any sampling point, the system is out of compliance with the MCL immediately.

1. Rounded to the same number of significant figures as the MCL for the contaminant in question.
2. If iron and manganese are present, the total concentration of both should not exceed 0.5 mg/L. Higher levels may be allowed by the State when justified by the supplier of water.
3. Water containing more than 20 mg/L of sodium should not be used for drinking by people on severely restricted sodium diets. Water containing more than 270 mg/L of sodium should not be used for drinking by people on moderately restricted sodium diets.
4. mg/L = milligrams per liter
5. Community and nontransient noncommunity systems using ozone for disinfection or oxidation must comply with the bromate standard. Systems using surface water or ground water under the direct influence of surface water and serving 10,000 or more people must comply by January 1, 2002. Systems using surface water or ground water under the direct influence of surface water and serving fewer than 10,000 people, or systems using ground water must comply by January 1, 2004.
6. Community and nontransient noncommunity systems using chlorine dioxide as a disinfectant or oxidant must comply with the chlorite standard. Systems using surface water or ground water under the direct influence of surface water and serving 10,000 or more people must comply by January 1, 2002. Systems using surface water or ground water under the direct influence of surface water and serving fewer than 10,000 people, or systems using ground water must comply by January 1, 2004.
7. Arsenic sampling results shall be reported to the nearest 0.001 mg/L.
8. Any sample below the method detection limit shall be calculated at zero for the purpose of determining the annual average. If a system fails to collect the required number of samples, compliance (average concentration) will be based on the total number of samples collected.
9. If confirmation samples are collected, the average of the initial sample and any confirmation samples will be used for the determination of compliance and future monitoring requirements.
10. Systems are only required to conduct the increased monitoring frequency at the sampling point where the MCL was exceeded and for only the specific contaminant(s) that triggered the system into the increased monitoring frequency.

1. An MCL of 20 mg/L may be permitted at a noncommunity water system if the supplier of water demonstrates that:
   1. the water will not be available to children under six months of age;
   2. a notice that nitrate levels exceed 10 mg/L and the potential health effects of exposure will be continuously posted according to the requirements of a Tier 1 notification;
   3. the State will be notified annually of nitrate levels that exceed 10 mg/L; and
   4. no adverse health effects shall result.
2. Systems unable to collect an additional sample within 24 hours must issue a Tier 1 notification and must collect the additional sample within two weeks of receiving the initial sample results.

1. Systems using surface water or ground water under the direct influence of surface water and serving 10,000 or more people must comply with the disinfection byproducts standards by January 1, 2002. Systems using surface water or ground water under the direct influence of surface water and serving fewer than 10,000 people, or systems using ground water must comply by January 1, 2004. Until then, community water systems serving fewer than 10,000 persons must comply with an MCL of 0.1 mg/L for total trihalomethanes.
2. A system that is installing granular activated carbon (GAC) or membrane technology to comply with the trihalomethane and haloacetic acid MCLs may apply to the State for an extension of up to 24 months past the compliance dates for those MCLs. Systems must comply with any interim measures and schedules of compliance set by the State.

1. Systems using surface water or ground water under the direct influence of surface water and serving 10,000 or more people must comply by January 1, 2002. Systems using surface water or ground water under the direct influence of surface water and serving fewer than 10,000 people, or systems using ground water must comply by January 1, 2004.
2. In cases where systems switch between the use of chlorine and chloramines for residual disinfection during the year, compliance must be determined by including together all monitoring results of both chlorine and chloramines.

5 NTU^3,4

A violation occurs when the average of two consecutive daily entry point analyses exceeds the MCL rounded off to the nearest whole number.

1. The requirements of this table apply to unfiltered systems that the State had determined, in writing pursuant to section 5-1.30 of this Subpart, must install filtration, until filtration is installed.
2. If the daily entry point analysis exceeds one NTU, a repeat sample must be taken as soon as practicable and preferably within one hour. If the repeat sample exceeds one NTU, the supplier of water must make State notification. The repeat sample must be used for the monthly average and the two consecutive day average.
3. If the two consecutive day average exceeds the MCL, the supplier of water shall analyze for microbiological contamination at a point downstream of the first consumer, but as close to the first consumer as is feasible. The additional microbiological sample should be taken within one hour as soon as feasible after determining the two consecutive day average. The supplier of water shall report the result of this microbiological analysis to the State within 48 hours of obtaining the result. The result of this analysis shall not be used for monitoring purposes.
4. NTU = Nephelometric Turbidity Units

1. The standards apply to systems with surface water sources or groundwater sources directly influenced by surface water.
2. NTU= Nephelometric Turbidity Unit
3. The performance standard applies to alternative filtration technologies capable of complying with requirement of section 5-1.30(b) of this Subpart as demonstrated to the department by pilot studies, unless the department sets a turbidity performance standard for a specific system.
4. System serving 10,000 or more people must comply by January 1, 2002. If the combined filter effluent turbidity exceeds 1 NTU, the system must consult with the State in accordance with paragraph 5-1.78 (d)(3) of this Subpart.
5. Systems serving fewer than 10,000 people must comply by January 14, 2005. If the combined filter effluent turbidity exceeds 1 NTU, the system must consult with the State in accordance with paragraph 5-1.78(d)(3) of this Subpart. Until January 14, 2005, the performance standard is 0.5 NTU and the turbidity level of representative samples of the filtered water must at no time exceed 5.0 NTU.

A violation occurs at systems collecting less than 40 samples per month when two or more samples are total coliform positive.

1. Compliance with the MCL for total coliform must be made by a public water system each month the system is required to monitor for total coliform.
2. All samples collected in accordance with Table 11 footnotes 1, 2, 4 and 5 of this section and samples collected in accordance with section 5-1.51(f) of this Subpart shall be included in determining compliance with the MCL unless any of the samples have been invalidated by the State.
3. If any total coliform sample is positive a set of repeat samples must be collected in accordance with Table 11 of this section.
4. For notification purpose, an Escherichia coli (E. coli) MCL violation is a public health hazard.

Gross alpha activity (including radium-226 but excluding radon and uranium)

 
15 picocuries per liter

1. The Radionuclides Rule including the MCLs and minimum monitoring requirements applies only to community water systems.
2. To judge compliance with the maximum contaminant levels, averages of data shall be used and shall be rounded to the same number of significant figures as the maximum contaminant level for the substance in question.
3. For systems monitoring more than once per year, compliance with the MCL is determined by a running annual average at each sampling point. If the average of any sampling point is greater than the MCL, then the system is out of compliance with the MCL.
4. For systems monitoring more than once a year, if any sample result will cause the running average to exceed the MCL at any sample point, e.g., a single sample result is greater than four times of the MCL, the system is out of compliance with the MCL immediately.
5. If a system does not collect all required samples when compliance is based on a running annual average of quarterly samples, compliance will be based on the running average of the samples collected.
6. If a sample result is less than the detection limit, zero will be used to calculate the annual average, unless a gross alpha particle activity is being used in lieu of radium-226 and/or uranium. If the gross alpha particle activity result is less than detection and is substituted for radium-226 and/or uranium, 1/2 the detection limit will be used to calculate the annual average.
7. If the MCL for radionuclides in this Table is exceeded, the community water system must give notice to the State.
8. A system must determine compliance with the MCL for beta particle and photon radioactivity by using the calculation described below:

   pCi/L found in sample (from laboratory results) divided by the pCi/L equivalent of 4 mrem of exposure equals the fraction of the maximum 4 mrem/year exposure limit

9. To determine compliance with the MCL, a system must monitor at a frequency as described in Table 12.
10. If the results show an MCL violation for any of the constituents, the system must conduct monthly monitoring for all species at any sampling point that exceeds the MCL. Monitoring must be conducted in accordance with Table 12 in this section. A system can resume quarterly monitoring if the rolling average of three months of samples is at or below the MCL.

GT = Greater Than
LT = Less Than

1. If a system is not vulnerable to asbestos contamination, either at its source or due to corrosion of asbestos cement pipe, it is not required to monitor if granted a waiver by the State. The waiver must be renewed by the State every nine years. The basis for a waiver must include the following:
   1. Lack of potential asbestos contamination of the water source
   2. No use of asbestos cement pipe for finished water distribution and noncorrosive nature of the water.
2. If asbestos monitoring data collected after January 1, 1990 are consistent with the requirements of this table, the State may allow systems to use that data to satisfy the initial monitoring requirement beginning January 1, 1993.
3. If a system is vulnerable to asbestos contamination due to source water and corrosion of asbestos cement pipe or solely to corrosion of asbestos cement pipe, it shall take one sample at a tap served by asbestos cement pipe and under conditions where asbestos contamination is most likely to occur.
4. If a system is vulnerable to asbestos contamination due to source water only, monitoring shall be conducted as follows:
   • Groundwater - Collect a minimum of one sample at every entry point to the distribution system representative of each well after treatment.
   • Surface water - Collect a minimum of one sample at each entry point to the distribution system after any application of treatment or in the distribution system at a point which is representative of each source after treatment.
5. For both types of water sources the system shall take each sample at the sample sampling point unless conditions make another sampling point more representative of each source or treatment plant. If a system draws water from more than one source and the sources are combined before distribution, the system must sample at an entry point to the distribution system during periods of normal operating conditions when water is representative of all sources.
6. A system which exceeds the MCL for asbestos shall monitor quarterly beginning in the next quarter after the violation occurred.
7. State may decrease the quarterly monitoring requirement to the initial sampling requirement provided that the State has determined that the system is reliably and consistently below the MCL on the basis of a minimum of two quarterly groundwater samples and a minimum of four quarterly samples for surface water.

1. A waiver from the required initial monitoring frequencies may be granted by the State, based upon the following conditions:
   1. A minimum of one sample shall be collected while the waiver is effective.
   2. Surface water systems must have monitored annually for at least three years and groundwater systems must have conducted a minimum of three rounds of monitoring with at least one sample taken since January 1, 1990.
   3. All results must be less than the MCL.
   4. New sources are not eligible for a waiver until completion of three rounds of sampling
   5. Waivers issued by the State shall be made in writing, shall cite the basis for determination and shall not exceed a maximum of nine years.
2. To determine the appropriate reduced monitoring frequency, the State shall consider:
   1. Reported concentrations from all previous monitoring
   2. Variations in reported concentrations; and
   3. other factors which may affect contaminant concentrations such as changes in groundwater pumping rates, changes in the system's configuration, operating procedures, stream flows or other characteristics
3. For all types of water sources the system shall take each sample at the same sampling point unless conditions make another sampling point more representative of each source or treatment plant. If a system draws water from more than one source and the sources are combined before distribution, the system must sample at an entry point to the distribution system during periods of normal operating conditions when water is representative of all sources, or separately at the individual sources. The State may allow systems to composite samples in accordance with the conditions in Appendix 5-C. All samples taken and analyzed in accordance with the monitoring plan must be included in determining compliance, even if the number is greater than the minimum required.
4. The State may decrease the quarterly monitoring requirement to the initial sampling requirement provided that it is determined that the system is reliably and consistently below the MCL on the basis of a minimum of two quarterly groundwater samples and a minimum of four quarterly samples for surface water.
5. If concentrations of a listed contaminant exceed the MCL, the Department requires the collection of an additional sample as soon as possible but not to exceed two weeks.
6. The State may require or the water system may request more frequent monitoring frequencies than is minimally required. The State, at its discretion, may require confirmation samples for positive and negative results.
7. The average of the initial and confirmation sample contaminant concentration at each sampling point shall be used to determine compliance with the MCL.
8. Systems with fewer than 150 service connections may postpone initial monitoring for antimony, beryllium, cyanide, nickel and thallium until 1998, but no later than three years after conducting its last result set of analysis for arsenic, barium, cadmium, mercury, selenium and fluoride.
9. Systems with fewer than 150 service connections may postpone initial monitoring for antimony, beryllium, cyanide, nickel and thallium until 1996.
10. State discretion shall mean requiring monitoring when the State has reason to believe the MCL has been violated, the potential exists for an MCL violation or the contaminant may present a risk to public health.
11. Community and nontransient noncommunity systems using ozone for disinfection or oxidation must comply with the bromate monitoring requirement. Systems using surface water or ground water under the direct influence of surface water and serving 10,000 or more people must comply by January 1, 2002. Systems using surface water or ground water under the direct influence of surface water and serving fewer than 10,000 people, or systems using ground water must comply by January 1, 2004.
12. Community and nontransient noncommunity systems using chlorine dioxide as a disinfectant or oxidant must comply with the chlorite monitoring requirement. Systems using surface water or ground water under the direct influence of surface water and serving 10,000 or more people must comply by January 1, 2002. Systems using surface water or ground water under the direct influence of surface water and serving fewer than 10,000 people, or systems using ground water must comply by January 1, 2004.
13. Systems required to analyze for bromate may reduce monitoring from monthly to once per quarter, if the system demonstrates that the average source water bromide concentration is less than 0.05 mg/L based on representative monthly bromide measurements for one year. A system may remain on reduced bromate monitoring until the running annual average source water bromide concentration, computed quarterly, is equal to or greater than 0.05 mg/L. If the average bromide concentration is equal to or greater than 0.05 mg/L, the system must resume routine monthly bromate monitoring.
14. On each day following a sample result that exceeds the chlorite MCL at the entrance to the distribution system, the system must take three chlorite distribution system samples at the following locations: as close to the first customer as possible, in a location representative of average residence time, and in a location representative of maximum residence time. The samples comprising the three-sample set required for routine monitoring must be collected at the same three locations in the distribution system that are used when following up on a daily MCL exceedance at the entry point. The system may use results of additional monitoring, conducted as the result of an entry point MCL exceedance, to meet the requirement for routine monthly monitoring.
15. Daily chlorite monitoring at the entrance to the distribution system may not be reduced. Monthly chlorite monitoring in the distribution system may be reduced to one three-sample set per quarter after one year of monitoring where no individual chlorite sample taken in the distribution system has exceeded the chlorite MCL. If the system has had to conduct distribution system monitoring as a result of an MCL exceedance at the entry point, the system cannot reduce monitoring. The system may remain on a reduced monitoring schedule until either any of the three individual chlorite samples taken quarterly in the distribution system exceeds the chlorite MCL or the system is required to conduct distribution system monitoring because of an entry point chlorite MCL exceedance.
16. A system must monitor according to its monitoring plan as described in section 5-1.51(c) of this Subpart. Failure to monitor in accordance with the monitoring plan is a monitoring violation.
17. Failure to monitor will be treated as a monitoring violation for the entire period covered by an annual average where compliance is based on an annual average of monthly or quarterly samples or averages and a system's failure to monitor makes it impossible to determine MCL compliance.

1. The State may require, or the water system may request, more frequent monitoring frequencies than is minimally required. The State at its discretion may require confirmation samples for positive and negative results.
2. Noncommunity water systems must sample annually beginning 1/1/93 regardless of the water source.
3. The frequency may be reduced to annual if the State determines the systems contaminant concentration is consistently and reliably less than the MCL and annual samples are collected during the quarter(s) having the highest analytical results.
4. A surface water shall return to quarterly monitoring if any one sample is GT 50 percent of MCL.
5. State discretion shall mean requiring monitoring when the State has reason to believe the MCL has been violated, the potential exists for an MCL violation or the contaminant may present a risk to public health.
6. For both types of water sources the system shall take each sample at the same sampling point unless conditions make another sampling point more representative of each source or treatment plant. If a system draws water from more than one source and the sources are combined before distribution, the system must sample at an entry point to the distribution system during periods of normal operating conditions when water is representative of all sources.

1. All community systems with sodium levels exceeding 20 mg/l will be required to sample for sodium analysis.
2. State discretion shall mean requiring monitoring when the State has reason to believe the MCL has been violated, the potential exists for an MCL violation or the contaminant may present a risk to public health.

Haloacetic Acids

1. A system must monitor according to its monitoring plan as described in section 5-1.51 (c) of this Subpart. Failure to monitor in accordance with the monitoring plan is a monitoring violation.
2. Effective January 1, 2002.
3. Failure to monitor will be treated as a monitoring violation for the entire period covered by an annual average where compliance is based on an annual average of monthly or quarterly samples or averages and a system's failure to monitor makes it impossible to determine MCL compliance. If a system fails to complete four consecutive quarters of monitoring, compliance with the MCL will be based on an average of the available data.
4. If, during the first year of monitoring, any individual quarter's average will cause the annual average of that system to exceed the MCL the system is out of compliance at the end of that quarter.
5. System may reduce monitoring if at least one year of samples have been collected and the annual average of total THMs is less than or equal to 0.040 mg/L and the annual average of haloacetic acids is less than or equal to 0.030 mg/L. In order to be eligible for reduced monitoring, the source water annual average total organic carbon (TOC) level, before any treatment, must be less than or equal to 4.0 mg/L. Systems on a reduced monitoring schedule may remain on that reduced schedule as long as the average of all samples taken in the year is no more than 0.060 mg/L and 0.045 mg/L for total trihalomethanes and haloacetic acids, respectively. Systems that exceed these levels must resume monitoring at the routine frequency in the quarter immediately following the exceedance.
6. If a system elects to sample more frequently than the minimum required, at least 25% of all samples collected each quarter (including those taken in excess of the required frequency) must be taken at locations that represent the maximum residence time of the water in the distribution system. The remaining samples must be taken at locations representative of at least average residence time in the distribution system. A system must sample at locations identified in a monitoring plan approved by the State.
7. Effective January 1, 2004. Until then, monitoring of these systems is at State's discretion.
8. State discretion shall mean requiring monitoring when the State has reason to believe the MCL has been violated, the potential exists for an MCL violation or the contaminant may present a risk to public health.
9. System may switch from routine monitoring to reduced monitoring if at least one year of samples have been collected and the annual average of total THMs is less than or equal to 0.040 mg/L and the annual average of haloacetic acids is less than or equal to 0.030 mg/L. Systems on a reduced monitoring schedule may remain on that reduced schedule as long as the result of the sample for the year is no more than 0.060 mg/L and 0.045 mg/L for total trihalomethanes and haloacetic acids, respectively. Systems that exceed these levels must resume quarterly monitoring in the quarter immediately following the exceedance.
10. The State may allow multiple wells drawing water from a single aquifer to be considered one treatment plant for determining the minimum number of samples required.
11. System may reduce monitoring if at least one year of samples have been collected and the annual average of total THMs is less than or equal to 0.040 mg/L and the annual average of haloacetic acids is less than or equal to 0.030 mg/L for two consecutive years, or if the annual average of total THMs is less than or equal to 0.020 mg/L and the annual average of haloacetic acids is less than 0.015 mg/L for one year. If a system qualifies for reduced monitoring, the three-year cycle will begin on January 1 following the quarter in which the system qualifies. Systems on a reduced monitoring schedule may remain on that reduced schedule as long as the result of the last sample is no more than 0.060 mg/L and 0.045 mg/L for total trihalomethanes and haloaceteric acids, respectively. Systems that exceed these levels must resume yearly monitoring in the year immediately following the exceedance.

1. The location for sampling of each groundwater source of supply shall be between the individual well and at or before the first service connection and before mixing with other sources, unless otherwise specified by the State to be at the entry point representative of the individual well. Public water systems which rely on a surface water shall sample at points in the distribution system representative of each source or at an entry point or points to the distribution system after any water treatment plant.
2. The State may decrease the quarterly monitoring requirement to annually provided that the system is reliably and consistently below the MCL based on a minimum of two quarterly samples from a groundwater source and four quarterly samples from a surface water source. Systems which monitor annually must monitor during the quarter which previously yielded the highest analytical result.
3. The State may reduce the frequency of monitoring of a groundwater source to once every three years for a public water system which has three consecutive annual samples with no detection of a contaminant.
4. The State may determine that a public water system is invulnerable to a contaminant or contaminants after evaluating every three years the following factors:
   1. Knowledge of previous use (including transport, storage, or disposal) of the contaminant within the watershed or zone of influence of the system. If a determination by the State reveals no previous use of the contaminant within the watershed or zone of influence, a waiver can be granted.
   2. If previous use of the contaminant is unknown or it has been used previously, then the following factors shall be used to determine whether a waiver can be granted.
      1. Previous analytical results.
      2. The proximity of the system to a potential point or nonpoint source of contamination. Point sources include spills and leaks of chemicals at or near a water treatment facility or at manufacturing, distribution, or storage facilities, or from hazardous and municipal waste landfills and other waste handling or treatment facilities.
      3. The environmental persistence and transport of the contaminants.
      4. The number of persons served by the public water system and the proximity of a smaller system to a larger system.
      5. How well the water source is protected against contamination, such as whether it is a surface or groundwater system. Groundwater systems must consider factors such as depth of the well, the type of soil, and wellhead protection. Surface water systems must consider watershed protection.
5. The State may reduce the initial monitoring requirement to one sample if the State determines that the system is invulnerable in accordance with footnote 4.
6. State discretion shall mean requiring monitoring when the State has reason to believe the MCL has been violated, the potential exists for an MCL violation or the contaminant may present a risk to public health.
7. The initial requirement does not apply to MTBE monitoring

1. If monitoring data collected after January 1, 1990 are consistent with the requirements of Appendix 5-C then the State may allow systems to use that data to satisfy the initial requirement. Systems serving a population of less than 3,300 persons shall not be required to collect additional quarterly monitoring for a specific contaminant or contaminants, if monitoring for only one quarter prior to October 1, 1993 did not detect the presence of such contaminant or contaminants.
2. The location for sampling of each groundwater source of supply shall be between the individual well and at or before the first service connection and before mixing with other sources, unless otherwise specified by the State to be at the entry point representative of the individual well. Public water systems which take water from a surface water body or watercourse shall sample at points in the distribution system representative of each source or at entry point or points to the distribution system after any water treatment plant.
3. The State may decrease the quarterly monitoring requirement to annually provided that system is reliably and consistently below the MCL based on a minimum of two quarterly samples from a groundwater source and four quarterly samples from a surface water source. Systems which monitor annually must monitor during the quarter that previously yielded the highest analytical result. Systems serving fewer than 3,300 persons and which have three consecutive annual samples without detection may apply to the State for a waiver in accordance with footnote 6.
4. The State may allow a system to postpone monitoring for a maximum of two years, if an approved laboratory is not reasonably available to do a required analysis within the scheduled monitoring period.
5. The State may waive the monitoring requirement for a public water system that submits information every three years to demonstrate that a contaminant or contaminants was not used, transported, stored or disposed within the watershed or zone of influence of the system.
6. The State may reduce the monitoring requirement for a public water system that submits information every three years to demonstrate that the public water system is invulnerable to contamination. If previous use of the contaminant is unknown or it has been used previously, then the following factors shall be used to determine whether a waiver is granted.
   1. Previous analytical results.
   2. The proximity of the system to a potential point or nonpoint source of contamination. Point sources include spills and leaks of chemicals at or near a water treatment facility or at manufacturing, distribution, or storage facilities, or from hazardous and municipal waste landfills and other waste handling or treatment facilities. Nonpoint sources include the use of pesticides to control insect and weed pests on agricultural areas, forest lands, home and gardens, and other land application uses.
   3. The environmental persistence and transport of the pesticide or PCBs.
   4. How well the water source is protected against contamination due to such factors as depth of the well and the type of soil and the integrity of the well casing.
   5. Elevated nitrate levels at the water supply source.
   6. Use of PCBs in equipment used in production, storage or distribution of water.
7. The State may allow systems to composite samples in accordance with the conditions in Appendix 5-C of this Title.
8. State discretion shall mean requiring monitoring when the State has reason to believe the MCL has been violated, the potential exists for an MCL violation or the contaminant may present a risk to public health.
9. If a contaminant is detected, repeat analysis must include all analytes contained in the approved analytical method in Appendix 5-C of this Title for the detected contaminant.
10. Detected as used in the table shall be defined as reported by the State approved laboratory to be greater than or equal to the method detection levels as specified in Appendix 5-C of this Title.

1. The requirements of this table apply to unfiltered systems that the State has determined, in writing pursuant to section 5-1.30 of this Subpart, must install filtration. These requirements only apply until filtration is installed.
2. State discretion shall mean requiring monitoring when the State has reason to believe the MCL has been violated, the potential exists for an MCL violation or the contaminant may present a risk to public health.

1. Surface water sources or groundwater sources directly influenced by surface water.
2. Effective January 1, 2002 systems serving 10,000 or more people must record the results of individual filter monitoring every fifteen minutes, and combined filter effluent every four hours. Effective January 14, 2005 systems serving fewer than 10,000 persons must record the results of individual filter monitoring every fifteen minutes, and combined filter effluent every four hours. Until January 14, 2005, systems serving fewer than 10,000 persons must continuously monitor the composite filter effluent turbidity, or record the turbidity every four hours. The state may allow systems with two filters to monitor the combined filter effluent continuously (recording every 15 minutes) in lieu of monitoring individual filter turbidity. Results of individual filter monitoring must be maintained for at least three years.
3. If there is a failure in the continuous turbidity monitoring equipment, the system must conduct grab sampling every four hours instead of continuous monitoring, but for no more than five working days following the failure of the equipment.
4. For systems using slow sand filtration or filtration treatment, other than conventional treatment, direct filtration or D.E. filtration, the State may reduce sampling frequency to once per day if it determines that less frequent monitoring is sufficient to indicate effective filtration performance.
5. If a system uses continuous monitoring, it must use the turbidity values recorded every four hours to determine if a treatment technique violation occurs, unless the State has approved in writing a different time interval.
6. State discretion shall mean requiring monitoring when the State has reason to believe the MCL has been violated, the potential exists for an MCL violation or the contaminant may present a risk to public health.

1. Public water supply systems must collect total coliform samples at sites which are representative of water throughout the distribution system and throughout the reporting period according to a written sample site plan which is subject of State review and revision.
2. Public water systems using surface water or groundwater directly influenced by surface water, and which do not provide filtration, must collect and analyze at least one sample for total coliforms near the first service connection each day the turbidity level of the raw water exceeds 1.49 NTU. This sample shall be collected within 24 hours. Results of this sample must be included in determining compliance with the MCL of total coliforms in Table 6 of this section.
3. Samples taken to determine disinfection practices after pipe repair, replacement, etc. are not to be used for determining MCL compliance for total coliforms in Table 6 of this section.
4. After any total coliform positive sample the system must collect at least four repeat samples on the same day and within 24 hours of being notified. One repeat sample must be from the same sampling site that the original coliform positive sample was collected, one repeat sample within five service connections upstream and one repeat sample within five service connections downstream and one taken at random in the distribution system. If one or more repeat samples are total coliform positive, another set of repeat samples must be collected. This process must be repeated until total coliform are not detected in one complete set or it is determined that the MCL has been violated. For systems with a single service connection a single repeat sample of at least 400 milliliters volume must be collected.
5. The month following repeat sample collection, the system must collect a minimum of five routine samples. The State may waive, in writing, the requirement to collect five routine samples the next month the system provides water to the public, if the State carries out an onsite visit before the end of the next month and the State determines why the sample was total coliform positive and establishes that the system has corrected the problem. The State can not waive the requirement to collect five routine samples solely on the basis that all the repeat samples were total coliform negative. A system must take at least one routine sample before the end of the next month it serves water to the public and the sample is to be used to determine compliance with the MCL in accordance with Table 6 of this section, unless the State determines that the system has corrected the problem before the system collected the sample required in Table 11, footnote 4 of this section and all repeat samples were total coliform negative.
6. If chlorine is used as the disinfectant, a free chlorine residual determination shall be made at the same time and location that the sample is collected for total coliform analysis. Monitoring for heterotrophic bacteria may be substituted for free chlorine residuals. A heterotrophic plate count result equal to or less than 500 colonies per milliliter is considered to be equivalent to a measurable free chlorine residual.
7. The State may, in writing, reduce the monitoring frequency to quarterly for a community water system serving 1,000 or fewer persons if the system has no history of total coliform contamination and a sanitary survey conducted in the past five years shows that the system is supplied solely by a protected groundwater source and the system and groundwater source are free of sanitary defects.

1. The monitoring requirement applies to surface water sources and groundwater sources directly influenced by surface water.
2. Either fecal or total coliform density measurements are acceptable. If both analyses are performed, the fecal coliform results will take precedence.
3. Monitoring sampling must be performed on separate days.
4. Samples must be taken and analyzed every day the system serves water to the public and the turbidity of the raw water exceeds 1.49 NTU. The samples count toward the weekly sampling requirement.

One sample every nine years at every entry point when monitoring results are below the detection limit.^7,8

One sample every six years at every entry point when monitoring results are at or above the detection limit but below half of the MCL.^7,8

One sample every three years at every entry point when monitoring results are above half of the MCL but at or below the MCL.^7,8

1. All radiological samples must be collected at every entry point to distribution systems (EPTDS).
2. The State may allow systems to reduce the frequency of monitoring based on initial monitoring or historical results as noted in footnote 4 below.
3. Systems on a reduced monitoring schedule must perform quarterly sampling if a sample result exceeds the MCL.
4. The State may allow historical monitoring data collected between June 2000 and December 8, 2003 for systems with:

   (1) only one entry point to the distribution system;

   (2) multiple entry points and having appropriate historical monitoring data for each entry point to the distribution system;

   (3) appropriate historical data for a representative point in the distribution system, provided that the State finds that the historical data satisfactorily demonstrate that each entry point to the distribution system is expected to be in compliance based upon the historical data and reasonable assumptions about the variability of contaminant levels between entry points.

5. The State may waive the final two quarters of initial monitoring for a sampling point if the results of the samples from the previous two quarters are below the detection limit.
6. If the average of the initial monitoring results for a sampling point is above the MCL, the system must collect and analyze quarterly samples at the sampling point until the system has results from four consecutive quarters that are at or below the MCL.
7. A gross alpha particle activity measurement may be substituted for the required radium-226 measurement provided that the measured gross alpha particle activity does not exceed 5 pCi/L. A gross alpha particle activity measurement may be substituted for the required uranium measurement provided that the measured gross alpha particle does not exceed 15 pCi/L. The gross alpha measurement shall have a confidence interval of 95% (1.65σ, where σ is the standard deviation of the net counting rate of the sample) for radium-226 and uranium. When a system uses a gross alpha particle activity measurement in lieu of a radium-226 and/or uranium measurement, the gross alpha particle activity analytical result will be used to determine the future monitoring frequency for radium-226 and/or uranium. If the gross alpha particle activity result is less than detection, 1/2 the detection limit can be used to substitute to radium-226 and determine compliance for future monitoring frequency.
8. Radium-228 measurement can not be substituted by the gross alpha particle activity result.
9. For systems in the vicinity of a nuclear facility, the State may allow the CWS to utilize environmental surveillance data collected by the nuclear facility in lieu of monitoring the systems entry point(s), where the State determines that such data is applicable.
10. Systems already designated by the State must continue to sample until the State reviews and either reaffirms or removes the designation.
11. Quarterly monitoring for gross beta particle activity shall be based on the analysis of monthly samples or the analysis of a composite of three monthly samples.
12. Annual monitoring for Sr-90 and tritium shall be conducted by means of the analysis of a composite of four consecutive quarterly samples or analysis of four quarterly samples.
13. For iodine-131, a composite of five consecutive daily samples shall be analyzed once each quarter. As ordered by the State, more frequent monitoring shall be conducted when iodine-131 is identified in the finished water.
14. Systems must collect all samples for beta emitters, tritium and strontium-90 during the reduced monitoring period.
15. A system that exceeds the gross beta particle activity minus the naturally occurring potassium-40 beta particle screening level (50 pCi/L for vulnerable systems or 15 pCi/L for systems utilizing waters contaminated by effluents from nuclear facilities), must further analyze the sample for the major radioactive constitutents. The potassium-40 beta particle activity must be calculated by multiplying elemental potassium concentrations in mg/L by a factor of 0.82.

1. MCL-maximum contaminant level, MRDL-maximum residual disinfectant level, TT-treatment technique
2. State notification must be made by the supplier of water within 24 hours of learning of an E. coli positive sample.
3. Public notification normally does not have to be issued for an E. coli positive sample prior to the results of the repeat samples. However, there may be situations where the State determines that a Tier 1 notification is necessary to protect the public health. The supplier of water must provide the Tier 1 notification no later than 24 hours after learning of the State's determination.
4. Failure to test for E. coli requires a Tier 1 notification if testing is not done after any repeat sample tests positive for coliform. All other E. coli monitoring and testing procedure violations require Tier 3 notification.
5. Tier 2 notification is normally required, however, there may be situations where the State determines that a Tier 1 notification is necessary to protect the public health. The supplier of water must provide the Tier 1 notification no later than 24 hours after learning of the State's determination.
6. Tier 1 notification is required if the situation meets the definition of a public health hazard.
7. If the daily entry point analysis exceeds one NTU, a repeat sample must be taken as soon as practicable and preferably within one hour. If the repeat sample exceeds one NTU, the supplier of water must make state notification.
8. Systems must consult with the State within 24 hours after learning of the violation. Based on this consultation, the State may subsequently decide to elevate the violation from a Tier 2 to a Tier 1 notification. If consultation does not take place within the 24 hour period, the water system must distribute a Tier 1 notification no later than 48 hours after the system learns of the violation.
9. These violations include the following: failure to comply with the treatment technique or monitoring requirements in section 5-1.30(b), (c), and (g) of this Subpart; failure to comply with the avoidance criteria in section 5-1.30(c) of this Subpart; and failure to install filtration or disinfection treatment facilities required by section 5-1.30 of this Subpart; failure to report to the state information required in section 5-1.72(c)(3) of this Subpart; and failure to maintain records required in section 5-1.72(c)(7) of this Subpart.
10. Applies to systems that have surface water or groundwater directly influenced by surface water as a source and use chlorine. The system must make State notification whether the residual was restored to at least 0.2 mg/L within four hours.
11. Failure to take a confirmation sample within 24 hours for nitrate or nitrite after an initial sample exceeds the MCL requires a Tier 1 notification. Other monitoring violations for nitrate or nitrite require a Tier 3 notification.
12. Failure to monitor for chlorine dioxide at the entrance to the distribution system the day after exceeding the MRDL at the entrance to the distribution system requires a Tier 2 notification. Other monitoring violations for chlorine dioxide at the entrance to the distribution system require a Tier 3 notification.
13. If any daily sample taken at the entrance to the distribution system exceeds the MRDL for chlorine dioxide and one or more samples taken in the distribution system the next day exceed the MRDL, Tier 1 notification is required. Failure to take the required samples in the distribution system the day after the MRDL is exceeded at the entry point also triggers Tier 1 notification.
14. State notification must be made by the supplier of water within 24 hours of learning of the violation.

1. These CT values achieve greater than a 99.99 percent inactivation of viruses. CT values between the indicated pH values may be determined by linear interpolation. CT values between the indicated temperatures of different tables may be determined by linear interpolation. If no interpolation is used, use the CT_99.9 value at the lower temperature, and at the higher pH.

1. These CT values achieve greater than a 99.99 percent inactivation of viruses. CT values between the indicated pH values may be determined by linear interpolation. CT values between the indicated temperatures of different tables may be determined by linear interpolation. If no interpolation is used, use the CT_99.9 value at the lower temperature, and at the higher pH.

1. These CT values achieve greater than a 99.99 percent inactivation of viruses. CT values between the indicated pH values may be determined by linear interpolation. CT values between the indicated temperatures of different tables may be determined by linear interpolation. If no interpolation is used, use the CT_99.9 value at the lower temperature, and at the higher pH.

1. These CT values achieve greater than a 99.99 percent inactivation of viruses. CT values between the indicated pH values may be determined by linear interpolation. CT values between the indicated temperatures of different tables may be determined by linear interpolation. If no interpolation is used, use the CT_99.9 value at the lower temperature, and at the higher pH.

1. These CT values achieve greater than a 99.99 percent inactivation of viruses. CT values between the indicated pH values may be determined by linear interpolation. CT values between the indicated temperatures of different tables may be determined by linear interpolation. If no interpolation is used, use the CT_99.9 value at the lower temperature, and at the higher pH.

1. These CT values achieve greater than a 99.99 percent inactivation of viruses. CT values between the indicated pH values may be determined by linear interpolation. If no interpolation is used, use the CT_99.9 value at the lower temperature for determining CT_99.9 values between indicated temperatures.
2. The use of these alternative disinfectants shall be approved in accordance with the provisions of section 5-1.22 of this Section.

1. If at any time the chlorine residual concentration falls below 0.2 mg/L the system must collect and analyze a grab sample every four hours until the chlorine residual concentration is again equal to or greater than 0.2 mg/L.
2. The day's grab samples may not be conducted at the same time.
3. If there is a failure in the continuous monitoring equipment, grab samples, every four hours, may be conducted in lieu of continuous monitoring, but for no more than five working days following the failure of the equipment.

1. CWS using surface water or ground water under the direct influence of surface water may use heterotrophic plate count results of equal to or less than 500 colonies per milliliter as equivalent to a free chlorine residual as outlined in table 11, footnote 6 in lieu of taking separate samples for disinfection residuals.
2. Monitoring is required if chlorine dioxide is used for either oxidation or disinfection.
3. If the MRDL of 0.8 mg/L is exceeded, the system must take three samples in the distribution system on the following day. If chlorine dioxide or chloramines are used to maintain a disinfectant residual in the distribution system, or if chlorine is used and there are no rechlorination stations, the system must take 3 samples as close to the first customer as possible, at intervals of at least 6 hours. If chlorine is used and there is a rechlorination station, the system must take one sample as close to the first customer as possible, one sample representing average residence time, and one sample representing maximum residence time.