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:

a. Lack of potential asbestos contamination of the water source.

b. 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 each 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 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.

⁶ A system which exceeds the MCL for asbestos shall monitor quarterly beginning in the next quarter after the violation occurred.

⁷ The 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.

GT - Greater Than

LT - Less Than

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 system's 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. The average of the initial and confirmation sample contaminant concentration at each sampling point shall be used to determine compliance with the MCL.

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.

¹ Notification must contain mandatory health effect language.

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 15 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 15 minutes, and combined filter effluent every four hours. Until January 14, 2005, systems serving fewer then 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 an MCL 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 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.

¹ All radiological samples must be collected at every entry point to distribution system (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 activity 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 activity measurement in lieu of a radium-226 and/or uranium measurement, the gross alpha particle activity analytical result will be used be determine the future monitoring frequency for radium-226 and/or or uranium. If the gross alpha particle activity result is less than detection, ½ 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.

¹⁰Systems already designed by the State must continue to sample until the State reviews and either reaffirms or removes the designation.

¹¹Quarterly 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.

¹²Annual 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.

¹³For 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.

¹⁴Systems must collect all samples for beta emitters, tritium and strontium-90 during the reduced monitoring period.

¹⁵A 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 constituents. The potassium-40 beta particle activity must be calculated by multiplying elemental potassium concentrations in mg/L by a factor of 0.82.

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 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 temperatures 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 Subpart.

¹ See also Table 15A for distribution system disinfectant residual sampling locations and frequency depending on disinfectant used.

² If at any time chlorine residual concentration falls below 0.2 mg/L at the entry point for a surface water or GWUDI system, 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.

³ Entry point samples collected at Surface Water or GWUDI systems.

⁴ The day's grab samples may not be conducted at the same time.

⁵ 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 (14 working days for ground water systems) following the failure of the equipment.

⁶ If at any time the disinfectant concentration at a ground water system falls below the minimum required in the process compliance monitoring plan approved by the State, the system must collect and analyze a grab sample every four hours until the disinfectant residual concentration is again at or above minimum required levels, without exceeding other applicable concentration requirements in Table 3A.

⁷ Any ground water system required to provide 4-log virus treatment because of fecal contamination of the source or because of significant deficiencies in system operation, and using chemical disinfection, must demonstrate minimum disinfectant residual at a location that demonstrates adequate concentration to provide the required treatment at the first customer during peak flow according to the sampling plan developed for the system. These samples to confirm the minimum disinfection residual are to be collected at the frequency in this table.

⁸ Lowest daily concentration must be recorded on operation report.

⁹ A minimum of one disinfectant residual concentration must be recorded on operation report every day.

¹ Community Water Systems 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 5, 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 Maximum Residual Disinfectant Level (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 three samples as close to the first customer as possible, at intervals of at least six 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.