near the intake on the same day and must follow either paragraph
(e)(2)(i) or (ii) of this section for sample analysis.
    (i) Systems may composite samples from each source into one sample
prior to analysis. The volume of sample from each source must be
weighted according to the proportion of the source in the total plant
flow at the time the sample is collected.
    (ii) Systems may analyze samples from each source separately and
calculate a weighted average of the analysis results for each sampling
date. The weighted average must be calculated by multiplying the
analysis result for each source by the fraction the source contributed
to total plant flow at the time the sample was collected and then
summing these values.
    (f) Additional Requirements. Systems must submit a description of
their sampling location(s) to the State at the same time as the
sampling schedule required under Sec.  141.702. This description must
address the position of the sampling location in relation to the
system's water source(s) and treatment processes, including
pretreatment, points of chemical treatment, and filter backwash
recycle. If the State does not respond to a system regarding sampling
location(s), the system must sample at the reported location(s).

Sec.  141.704  Analytical methods.

    (a) Cryptosporidium. Systems must analyze for Cryptosporidium using
Method 1623: Cryptosporidium and Giardia in Water by Filtration/IMS/FA,
2005, United States Environmental Protection Agency, EPA-815-R-05-002
or Method 1622: Cryptosporidium in Water by Filtration/IMS/FA, 2005,
United States Environmental Protection Agency, EPA-815-R-05-001, which
are incorporated by reference. The Director of the Federal Register
approves this incorporation by reference in accordance with 5 U.S.C.
552(a) and 1 CFR part 51. You may obtain a copy of these methods online
from http://www.epa.gov/safewater/disinfection/lt2 or from the United

States Environmental Protection Agency, Office of Ground Water and
Drinking Water, 1201 Constitution Ave., NW, Washington, DC 20460
(Telephone:<PHONE_NUMBER>). You may inspect a copy at the Water Docket
in the EPA Docket Center, 1301 Constitution Ave., NW, Washington, DC,
(Telephone:<PHONE_NUMBER>) or at the National Archives and Records
Administration (NARA). For information on the availability of this
material at NARA, call<PHONE_NUMBER>, or go to: http://www.archives.gov/federal_register/code_of_federal_regulations/ibr_locations.html
.

    (1) Systems must analyze at least a 10 L sample or a packed pellet
volume of at least 2 mL as generated by the methods listed in paragraph
(a) of this section. Systems unable to process a 10 L sample must
analyze as much sample volume as can be filtered by two filters
approved by EPA for the methods listed in paragraph (a) of this
section, up to a packed pellet volume of at least 2 mL.
    (2)(i) Matrix spike (MS) samples, as required by the methods in
paragraph (a) of this section, must be spiked and filtered by a
laboratory approved for Cryptosporidium analysis under Sec.  141.705.
    (ii) If the volume of the MS sample is greater than 10 L, the
system may filter all but 10 L of the MS sample in the field, and ship
the filtered sample and the remaining 10 L of source water to the
laboratory. In this case, the laboratory must spike the remaining 10 L
of water and filter it through the filter used to collect the balance
of the sample in the field.
    (3) Flow cytometer-counted spiking suspensions must be used for MS
samples and ongoing precision and recovery (OPR) samples.
    (b) E. coli. Systems must use methods for enumeration of E. coli in
source water approved in Sec.  136.3(a) of this title.
    (1) The time from sample collection to initiation of analysis may
not exceed 30 hours unless the system meets the condition of paragraph
(b)(2) of this section.
    (2) The State may approve on a case-by-case basis the holding of an
E. coli sample for up to 48 hours between sample collection and
initiation of analysis if the State determines that analyzing an E.
coli sample within 30 hours is not feasible. E. coli samples held
between 30 to 48 hours must be analyzed by the Colilert reagent version
of Standard Method 9223B as listed in Sec.  136.3(a) of this title.
    (3) Systems must maintain samples between 0[deg]C and 10[deg]C
during storage and transit to the laboratory.
    (c) Turbidity. Systems must use methods for turbidity measurement
approved in Sec.  141.74(a)(1).

Sec.  141.705  Approved laboratories.

    (a) Cryptosporidium. Systems must have Cryptosporidium samples
analyzed by a laboratory that is approved under EPA's Laboratory
Quality Assurance Evaluation Program for Analysis of Cryptosporidium in
Water or a laboratory that has been certified for Cryptosporidium
analysis by an equivalent State laboratory certification program.
    (b) E. coli. Any laboratory certified by the EPA, the National
Environmental Laboratory Accreditation Conference or the State for
total coliform or fecal coliform analysis under Sec. 141.74 is approved
for E. coli analysis under this subpart when the laboratory uses the
same technique for E. coli that the laboratory uses for Sec.  141.74.
    (c) Turbidity. Measurements of turbidity must be made by a party
approved by the State.

Sec. 141.706  Reporting source water monitoring results.

    (a) Systems must report results from the source water monitoring
required under Sec. 141.701 no later than 10 days after the end of the
first month following the month when the sample is collected.
    (b)(1) All systems serving at least 10,000 people must report the
results from the initial source water monitoring required under Sec.
141.701(a) to EPA electronically at https://intranet.epa.gov/lt2/.

    (2) If a system is unable to report monitoring results
electronically, the system may use an alternative approach for
reporting monitoring results that EPA approves.
    (c) Systems serving fewer than 10,000 people must report results
from the initial source water monitoring required under Sec.
141.701(a) to the State.
    (d) All systems must report results from the second round of source
water monitoring required under Sec.  141.701(b) to the State.
    (e) Systems must report the applicable information in paragraphs
(e)(1) and (2) of this section for the source water monitoring required
under Sec.  141.701.
    (1) Systems must report the following data elements for each
Cryptosporidium analysis:

                              Data element.

1. PWS ID.
2. Facility ID.

3. Sample collection date.
4. Sample type (field or matrix spike).
5. Sample volume filtered (L), to nearest \1/4\ L.
6. Was 100% of filtered volume examined.
7. Number of oocysts counted.

    (i) For matrix spike samples, systems must also report the sample
volume spiked and estimated number of oocysts spiked. These data are
not required for field samples.
    (ii) For samples in which less than 10 L is filtered or less than
100% of the sample volume is examined, systems must also report the
number of filters used and the packed pellet volume.
    (iii) For samples in which less than 100% of sample volume is
examined, systems must also report the volume of resuspended
concentrate and volume of this resuspension processed through
immunomagnetic separation.
    (2) Systems must report the following data elements for each E.
coli analysis:

Data element.

1. PWS ID.
2. Facility ID.
3. Sample collection date.
4. Analytical method number.
5. Method type.
6. Source type (flowing stream, lake/reservoir, GWUDI).
7. E. coli/100 mL.
8. Turbidity.\1\

\1\ Systems serving fewer than 10,000 people that are not required to
  monitor for turbidity under Sec.   141.701 are not required to report
  turbidity with their E. coli results.

Sec.  141.707  Grandfathering previously collected data.

    (a)(1) Systems may comply with the initial source water monitoring
requirements of Sec.  141.701(a) by grandfathering sample results
collected before the system is required to begin monitoring (i.e.,
previously collected data). To be grandfathered, the sample results and
analysis must meet the criteria in this section and the State must
approve.
    (2) A filtered system may grandfather Cryptosporidium samples to
meet the requirements of Sec.  141.701(a) when the system does not have
corresponding E. coli and turbidity samples. A system that grandfathers
Cryptosporidium samples without E. coli and turbidity samples is not
required to collect E. coli and turbidity samples when the system
completes the requirements for Cryptosporidium monitoring under Sec.
141.701(a).
    (b) E. coli sample analysis. The analysis of E. coli samples must
meet the analytical method and approved laboratory requirements of
Sec. Sec.  141.704 through 141.705.
    (c) Cryptosporidium sample analysis. The analysis of
Cryptosporidium samples must meet the criteria in this paragraph.
    (1) Laboratories analyzed Cryptosporidium samples using one of the
analytical methods in paragraphs (c)(1)(i) through (vi) of this
section, which are incorporated by reference. The Director of the
Federal Register approves this incorporation by reference in accordance
with 5 U.S.C. 552(a) and 1 CFR part 51. You may obtain a copy of these
methods on-line from the United States Environmental Protection Agency,
Office of Ground Water and Drinking Water, 1201 Constitution Ave, NW,
Washington, DC 20460 (Telephone:<PHONE_NUMBER>). You may inspect a copy
at the Water Docket in the EPA Docket Center, 1301 Constitution Ave.,
NW, Washington, DC, (Telephone:<PHONE_NUMBER>) or at the National
Archives and Records Administration (NARA). For information on the
availability of this material at NARA, call<PHONE_NUMBER>, or go to:
http://www.archives.gov/federal_ register/code--of--federal--

regulations/ibr--locations.html.
    (i) Method 1623: Cryptosporidium and Giardia in Water by
Filtration/IMS/FA, 2005, United States Environmental Protection Agency,
EPA-815-R-05-002.
    (ii) Method 1622: Cryptosporidium in Water by Filtration/IMS/FA,
2005, United States Environmental Protection Agency, EPA-815-R-05-001.
    (iii) Method 1623: Cryptosporidium and Giardia in Water by
Filtration/IMS/FA, 2001, United States Environmental Protection Agency,
EPA-821-R-01-025.
    (iv) Method 1622: Cryptosporidium in Water by Filtration/IMS/FA,
2001, United States Environmental Protection Agency, EPA-821--R-01-026.
    (v) Method 1623: Cryptosporidium and Giardia in Water by
Filtration/IMS/FA, 1999, United States Environmental Protection Agency,
EPA-821-R-99-006.
    (vi) Method 1622: Cryptosporidium in Water by Filtration/IMS/FA,
1999, United States Environmental Protection Agency, EPA-821-R-99-001.
    (2) For each Cryptosporidium sample, the laboratory analyzed at
least 10 L of sample or at least 2 mL of packed pellet or as much
volume as could be filtered by 2 filters that EPA approved for the
methods listed in paragraph (c)(1) of this section.
    (d) Sampling location. The sampling location must meet the
conditions in Sec.  141.703.
    (e) Sampling frequency. Cryptosporidium samples were collected no
less frequently than each calendar month on a regular schedule,
beginning no earlier than January 1999. Sample collection intervals may
vary for the conditions specified in Sec.  141.702(b)(1) and (2) if the
system provides documentation of the condition when reporting
monitoring results.
    (1) The State may approve grandfathering of previously collected
data where there are time gaps in the sampling frequency if the system
conducts additional monitoring the State specifies to ensure that the
data used to comply with the initial source water monitoring
requirements of Sec.  141.701(a) are seasonally representative and
unbiased.
    (2) Systems may grandfather previously collected data where the
sampling frequency within each month varied. If the Cryptosporidium
sampling frequency varied, systems must follow the monthly averaging
procedure in Sec.  141.710(b)(5) or Sec.  141.712(a)(3), as applicable,
when calculating the bin classification for filtered systems or the
mean Cryptosporidium concentration for unfiltered systems.
    (f) Reporting monitoring results for grandfathering. Systems that
request to grandfather previously collected monitoring results must
report the following information by the applicable dates listed in this
paragraph. Systems serving at least 10,000 people must report this
information to EPA unless the State approves reporting to the State
rather than EPA. Systems serving fewer than 10,000 people must report
this information to the State.
    (1) Systems must report that they intend to submit previously
collected monitoring results for grandfathering. This report must
specify the number of previously collected results the system will
submit, the dates of the first and last sample, and whether a system
will conduct additional source water monitoring to meet the
requirements of Sec.  141.701(a). Systems must report this information
no later than the date the sampling schedule under Sec.  141.702 is
required.
    (2) Systems must report previously collected monitoring results for
grandfathering, along with the associated documentation listed in
paragraphs (f)(2)(i) through (iv) of this section, no later than two
months after the applicable date listed in Sec.  141.701(c).
    (i) For each sample result, systems must report the applicable data
elements in Sec.  141.706.
    (ii) Systems must certify that the reported monitoring results
include all results the system generated during the time period
beginning with the first reported result and ending with the final
reported result. This applies to samples that were collected from the

sampling location specified for source water monitoring under this
subpart, not spiked, and analyzed using the laboratory's routine
process for the analytical methods listed in this section.
    (iii) Systems must certify that the samples were representative of
a plant's source water(s) and the source water(s) have not changed.
Systems must report a description of the sampling location(s), which
must address the position of the sampling location in relation to the
system's water source(s) and treatment processes, including points of
chemical addition and filter backwash recycle.
    (iv) For Cryptosporidium samples, the laboratory or laboratories
that analyzed the samples must provide a letter certifying that the
quality control criteria specified in the methods listed in paragraph
(c)(1) of this section were met for each sample batch associated with
the reported results. Alternatively, the laboratory may provide bench
sheets and sample examination report forms for each field, matrix
spike, IPR, OPR, and method blank sample associated with the reported
results.
    (g) If the State determines that a previously collected data set
submitted for grandfathering was generated during source water
conditions that were not normal for the system, such as a drought, the
State may disapprove the data. Alternatively, the State may approve the
previously collected data if the system reports additional source water
monitoring data, as determined by the State, to ensure that the data
set used under Sec.  141.710 or Sec.  141.712 represents average source
water conditions for the system.
    (h) If a system submits previously collected data that fully meet
the number of samples required for initial source water monitoring
under Sec.  141.701(a) and some of the data are rejected due to not
meeting the requirements of this section, systems must conduct
additional monitoring to replace rejected data on a schedule the State
approves. Systems are not required to begin this additional monitoring
until two months after notification that data have been rejected and
additional monitoring is necessary.

Disinfection Profiling and Benchmarking Requirements

Sec.  141.708  Requirements when making a significant change in
disinfection practice.

    (a) Following the completion of initial source water monitoring
under Sec.  141.701(a), a system that plans to make a significant
change to its disinfection practice, as defined in paragraph (b) of
this section, must develop disinfection profiles and calculate
disinfection benchmarks for Giardia lamblia and viruses as described in
Sec.  141.709. Prior to changing the disinfection practice, the system
must notify the State and must include in this notice the information
in paragraphs (a)(1) through (3) of this section.
    (1) A completed disinfection profile and disinfection benchmark for
Giardia lamblia and viruses as described in Sec.  141.709.
    (2) A description of the proposed change in disinfection practice.
    (3) An analysis of how the proposed change will affect the current
level of disinfection.
    (b) Significant changes to disinfection practice are defined as
follows:
    (1) Changes to the point of disinfection;
    (2) Changes to the disinfectant(s) used in the treatment plant;
    (3) Changes to the disinfection process; or
    (4) Any other modification identified by the State as a significant
change to disinfection practice.

Sec.  141.709  Developing the disinfection profile and benchmark.

    (a) Systems required to develop disinfection profiles under Sec.
141.708 must follow the requirements of this section. Systems must
monitor at least weekly for a period of 12 consecutive months to
determine the total log inactivation for Giardia lamblia and viruses.
If systems monitor more frequently, the monitoring frequency must be
evenly spaced. Systems that operate for fewer than 12 months per year
must monitor weekly during the period of operation. Systems must
determine log inactivation for Giardia lamblia through the entire
plant, based on CT99.9 values in Tables 1.1 through 1.6, 2.1
and 3.1 of Sec.  141.74(b) as applicable. Systems must determine log
inactivation for viruses through the entire treatment plant based on a
protocol approved by the State.
    (b) Systems with a single point of disinfectant application prior
to the entrance to the distribution system must conduct the monitoring
in paragraphs (b)(1) through (4) of this section. Systems with more
than one point of disinfectant application must conduct the monitoring
in paragraphs (b)(1) through (4) of this section for each disinfection
segment. Systems must monitor the parameters necessary to determine the
total inactivation ratio, using analytical methods in Sec.  141.74(a).
    (1) For systems using a disinfectant other than UV, the temperature
of the disinfected water must be measured at each residual disinfectant
concentration sampling point during peak hourly flow or at an
alternative location approved by the State.
    (2) For systems using chlorine, the pH of the disinfected water
must be measured at each chlorine residual disinfectant concentration
sampling point during peak hourly flow or at an alternative location
approved by the State.
    (3) The disinfectant contact time(s) (t) must be determined during
peak hourly flow.
    (4) The residual disinfectant concentration(s) (C) of the water
before or at the first customer and prior to each additional point of
disinfectant application must be measured during peak hourly flow.
    (c) In lieu of conducting new monitoring under paragraph (b) of
this section, systems may elect to meet the requirements of paragraphs
(c)(1) or (2) of this section.
    (1) Systems that have at least one year of existing data that are
substantially equivalent to data collected under the provisions of
paragraph (b) of this section may use these data to develop
disinfection profiles as specified in this section if the system has
neither made a significant change to its treatment practice nor changed
sources since the data were collected. Systems may develop disinfection
profiles using up to three years of existing data.
    (2) Systems may use disinfection profile(s) developed under Sec.
141.172 or Sec. Sec.  141.530 through 141.536 in lieu of developing a
new profile if the system has neither made a significant change to its
treatment practice nor changed sources since the profile was developed.
Systems that have not developed a virus profile under Sec.  141.172 or
Sec. Sec.  141.530 through 141.536 must develop a virus profile using
the same monitoring data on which the Giardia lamblia profile is based.
    (d) Systems must calculate the total inactivation ratio for Giardia
lamblia as specified in paragraphs (d)(1) through (3) of this section.
    (1) Systems using only one point of disinfectant application may
determine the total inactivation ratio for the disinfection segment
based on either of the methods in paragraph (d)(1)(i) or (ii) of this
section.
    (i) Determine one inactivation ratio (CTcalc/CT99.9)
before or at the first customer during peak hourly flow.
    (ii) Determine successive CTcalc/CT99.9 values,
representing sequential inactivation ratios, between the point of
disinfectant application and a point before or at the first customer
during peak hourly flow. The system must

calculate the total inactivation ratio by determining (CTcalc/
CT99.9) for each sequence and then adding the (CTcalc/
CT99.9) values together to determine ([Sigma] (CTcalc/
CT99.9)).
    (2) Systems using more than one point of disinfectant application
before the first customer must determine the CT value of each
disinfection segment immediately prior to the next point of
disinfectant application, or for the final segment, before or at the
first customer, during peak hourly flow. The (CTcalc/CT99.9)
value of each segment and ([Sigma] (CTcalc/CT99.9)) must be
calculated using the method in paragraph (d)(1)(ii) of this section.
    (3) The system must determine the total logs of inactivation by
multiplying the value calculated in paragraph (d)(1) or (d)(2) of this
section by 3.0.
    (4) Systems must calculate the log of inactivation for viruses
using a protocol approved by the State.
    (e) Systems must use the procedures specified in paragraphs (e)(1)
and (2) of this section to calculate a disinfection benchmark.
    (1) For each year of profiling data collected and calculated under
paragraphs (a) through (d) of this section, systems must determine the
lowest mean monthly level of both Giardia lamblia and virus
inactivation. Systems must determine the mean Giardia lamblia and virus
inactivation for each calendar month for each year of profiling data by
dividing the sum of daily or weekly Giardia lamblia and virus log
inactivation by the number of values calculated for that month.
    (2) The disinfection benchmark is the lowest monthly mean value
(for systems with one year of profiling data) or the mean of the lowest
monthly mean values (for systems with more than one year of profiling
data) of Giardia lamblia and virus log inactivation in each year of
profiling data.

Treatment Technique Requirements

Sec.  141.710  Bin classification for filtered systems.

    (a) Following completion of the initial round of source water
monitoring required under Sec.  141.701(a), filtered systems must
calculate an initial Cryptosporidium bin concentration for each plant
for which monitoring was required. Calculation of the bin concentration
must use the Cryptosporidium results reported under Sec.  141.701(a)
and must follow the procedures in paragraphs (b)(1) through (5) of this
section.
    (b)(1) For systems that collect a total of at least 48 samples, the
bin concentration is equal to the arithmetic mean of all sample
concentrations.
    (2) For systems that collect a total of at least 24 samples, but
not more than 47 samples, the bin concentration is equal to the highest
arithmetic mean of all sample concentrations in any 12 consecutive
months during which Cryptosporidium samples were collected.
    (3) For systems that serve fewer than 10,000 people and monitor for
Cryptosporidium for only one year (i.e., collect 24 samples in 12
months), the bin concentration is equal to the arithmetic mean of all
sample concentrations.
    (4) For systems with plants operating only part of the year that
monitor fewer than 12 months per year under Sec.  141.701(e), the bin
concentration is equal to the highest arithmetic mean of all sample
concentrations during any year of Cryptosporidium monitoring.
    (5) If the monthly Cryptosporidium sampling frequency varies,
systems must first calculate a monthly average for each month of
monitoring. Systems must then use these monthly average concentrations,
rather than individual sample concentrations, in the applicable
calculation for bin classification in paragraphs (b)(1) through (4) of
this section.
    (c) Filtered systems must determine their initial bin
classification from the following table and using the Cryptosporidium
bin concentration calculated under paragraphs (a)-(b) of this section:

              Bin Classification Table for Filtered Systems
------------------------------------------------------------------------
                                With a Cryptosporidium       The bin
     For systems that are:      bin concentration of .   classification
                                        . .\1\              is . . .
------------------------------------------------------------------------
. . . required to monitor for   Cryptosporidium < 0.075  Bin 1.
 Cryptosporidium under Sec.      oocyst/L.
 141.701.
                                 0.075 oocysts/L        Bin 2.
                                 < =Cryptosporidium
                                 < 1.0 oocysts/L.
                                 1.0 oocysts/L          Bin 3.
                                 < =Cryptosporidium
                                 < 3.0 oocysts/L.
                                 Cryptosporidium >=3.0  Bin 4.
                                 oocysts/L.
. . . serving fewer than        NA....................  Bin 1.
 10,000 people and NOT
 required to monitor for
 Cryptosporidium under Sec.
 141.701(a)(4).
------------------------------------------------------------------------
\1\ Based on calculations in paragraph (a) or (d) of this section, as
  applicable.

    (d) Following completion of the second round of source water
monitoring required under Sec.  141.701(b), filtered systems must
recalculate their Cryptosporidium bin concentration using the
Cryptosporidium results reported under Sec.  141.701(b) and following
the procedures in paragraphs (b)(1) through (4) of this section.
Systems must then redetermine their bin classification using this bin
concentration and the table in paragraph (c) of this section.
    (e)(1) Filtered systems must report their initial bin
classification under paragraph (c) of this section to the State for
approval no later than 6 months after the system is required to
complete initial source water monitoring based on the schedule in Sec.
141.701(c).
    (2) Systems must report their bin classification under paragraph
(d) of this section to the State for approval no later than 6 months
after the system is required to complete the second round of source
water monitoring based on the schedule in Sec.  141.701(c).
    (3) The bin classification report to the State must include a
summary of source water monitoring data and the calculation procedure
used to determine bin classification.
    (f) Failure to comply with the conditions of paragraph (e) of this
section is a violation of the treatment technique requirement.

Sec.  141.711  Filtered system additional Cryptosporidium treatment
requirements.

    (a) Filtered systems must provide the level of additional treatment
for Cryptosporidium specified in this paragraph based on their bin
classification as determined under Sec.  141.710 and according to the
schedule in Sec.  141.713.

----------------------------------------------------------------------------------------------------------------
                         And the system uses the following filtration treatment in full compliance with subparts
                         H, P, and T of this part (as applicable), then the additional Cryptosporidium treatment
   If the system bin                                     requirements are . . .
 classification is . . -----------------------------------------------------------------------------------------
           .                 Conventional                                 Slow sand or           Alternative
                         filtration treatment    Direct filtration     diatomaceous earth        filtration
                        (including softening)                              filtration           technologies
----------------------------------------------------------------------------------------------------------------
Bin 1.................  No additional          No additional          No additional         No additional
                         treatment.             treatment.             treatment.            treatment.
Bin 2.................  1-log treatment......  1.5-log treatment....  1-log treatment.....  (\1\)
Bin 3.................  2-log treatment......  2.5-log treatment....  2-log treatment.....  (\2\)
Bin 4.................  2.5-log treatment....  3-log treatment......  2.5-log treatment...  (\3\)
----------------------------------------------------------------------------------------------------------------
\1\ As determined by the State such that the total Cryptosporidium removal and inactivation is at least 4.0-log.

\2\ As determined by the State such that the total Cryptosporidium removal and inactivation is at least 5.0-log.

\3\ As determined by the State such that the total Cryptosporidium removal and inactivation is at least 5.5-log.

    (b)(1) Filtered systems must use one or more of the treatment and
management options listed in Sec.  141.715, termed the microbial
toolbox, to comply with the additional Cryptosporidium treatment
required in paragraph (a) of this section.
    (2) Systems classified in Bin 3 and Bin 4 must achieve at least 1-
log of the additional Cryptosporidium treatment required under
paragraph (a) of this section using either one or a combination of the
following: bag filters, bank filtration, cartridge filters, chlorine
dioxide, membranes, ozone, or UV, as described in Sec. Sec.  141.716
through 141.720.
    (c) Failure by a system in any month to achieve treatment credit by
meeting criteria in Sec. Sec.  141.716 through 141.720 for microbial
toolbox options that is at least equal to the level of treatment
required in paragraph (a) of this section is a violation of the
treatment technique requirement.
    (d) If the State determines during a sanitary survey or an
equivalent source water assessment that after a system completed the
monitoring conducted under Sec.  141.701(a) or Sec.  141.701(b),
significant changes occurred in the system's watershed that could lead
to increased contamination of the source water by Cryptosporidium, the
system must take actions specified by the State to address the
contamination. These actions may include additional source water
monitoring and/or implementing microbial toolbox options listed in
Sec.  141.715.

Sec.  141.712  Unfiltered system Cryptosporidium treatment
requirements.

    (a) Determination of mean Cryptosporidium level. (1) Following
completion of the initial source water monitoring required under Sec.
141.701(a), unfiltered systems must calculate the arithmetic mean of
all Cryptosporidium sample concentrations reported under Sec.
141.701(a). Systems must report this value to the State for approval no
later than 6 months after the month the system is required to complete
initial source water monitoring based on the schedule in Sec.
141.701(c).
    (2) Following completion of the second round of source water
monitoring required under Sec.  141.701(b), unfiltered systems must
calculate the arithmetic mean of all Cryptosporidium sample
concentrations reported under Sec.  141.701(b). Systems must report
this value to the State for approval no later than 6 months after the
month the system is required to complete the second round of source
water monitoring based on the schedule in Sec.  141.701(c).
    (3) If the monthly Cryptosporidium sampling frequency varies,
systems must first calculate a monthly average for each month of
monitoring. Systems must then use these monthly average concentrations,
rather than individual sample concentrations, in the calculation of the
mean Cryptosporidium level in paragraphs (a)(1) or (2) of this section.
    (4) The report to the State of the mean Cryptosporidium levels
calculated under paragraphs (a)(1) and (2) of this section must include
a summary of the source water monitoring data used for the calculation.
    (5) Failure to comply with the conditions of paragraph (a) of this
section is a violation of the treatment technique requirement.
    (b) Cryptosporidium inactivation requirements. Unfiltered systems
must provide the level of inactivation for Cryptosporidium specified in
this paragraph, based on their mean Cryptosporidium levels as
determined under paragraph (a) of this section and according to the
schedule in Sec.  141.713.
    (1) Unfiltered systems with a mean Cryptosporidium level of 0.01
oocysts/L or less must provide at least 2-log Cryptosporidium
inactivation.
    (2) Unfiltered systems with a mean Cryptosporidium level of greater
than 0.01 oocysts/L must provide at least 3-log Cryptosporidium
inactivation.
    (c) Inactivation treatment technology requirements. Unfiltered
systems must use chlorine dioxide, ozone, or UV as described in Sec.
141.720 to meet the Cryptosporidium inactivation requirements of this
section.
    (1) Systems that use chlorine dioxide or ozone and fail to achieve
the Cryptosporidium inactivation required in paragraph (b) of this
section on more than one day in the calendar month are in violation of
the treatment technique requirement.
    (2) Systems that use UV light and fail to achieve the
Cryptosporidium inactivation required in paragraph (b) of this section
by meeting the criteria in Sec.  141.720(d)(3)(ii) are in violation of
the treatment technique requirement.
    (d) Use of two disinfectants. Unfiltered systems must meet the
combined Cryptosporidium inactivation requirements of this section and
Giardia lamblia and virus inactivation requirements of Sec.  141.72(a)
using a minimum of two disinfectants, and each of two disinfectants
must separately achieve the total inactivation required for either
Cryptosporidium, Giardia lamblia, or viruses.

Sec.  141.713  Schedule for compliance with Cryptosporidium treatment
requirements.

    (a) Following initial bin classification under Sec.  141.710(c),
filtered systems must provide the level of treatment for
Cryptosporidium required under Sec.  141.711 according to the schedule
in paragraph (c) of this section.
    (b) Following initial determination of the mean Cryptosporidium
level under Sec.  141.712(a)(1), unfiltered systems must provide the
level of treatment for Cryptosporidium required under Sec.  141.712
according to the schedule in paragraph (c) of this section.
    (c) Cryptosporidium treatment compliance dates.

            Cryptosporidium Treatment Compliance Dates Table
------------------------------------------------------------------------
                                                  Must comply with
                                              Cryptosporidium treatment
         Systems that serve . . .           requirements no later than .
                                                       . . \a\
------------------------------------------------------------------------
(1) At least 100,000 people...............  (i) April 1, 2012.
(2) From 50,000 to 99,999 people..........  (i) October 1, 2012.
(3) From 10,000 to 49,999 people..........  (i) October 1, 2013.
(4) Fewer than 10,000 people..............  (i) October 1, 2014.
------------------------------------------------------------------------
a States may allow up to an additional two years for complying with the
  treatment requirement for systems making capital improvements.

    (d) If the bin classification for a filtered system changes
following the second round of source water monitoring, as determined
under Sec.  141.710(d), the system must provide the level of treatment
for Cryptosporidium required under Sec.  141.711 on a schedule the
State approves.
    (e) If the mean Cryptosporidium level for an unfiltered system
changes following the second round of monitoring, as determined under
Sec.  141.712(a)(2), and if the system must provide a different level
of Cryptosporidium treatment under Sec.  141.712 due to this change,
the system must meet this treatment requirement on a schedule the State
approves.

Sec.  141.714  Requirements for uncovered finished water storage
facilities.

    (a) Systems using uncovered finished water storage facilities must
comply with the conditions of this section.
    (b) Systems must notify the State of the use of each uncovered
finished water storage facility no later than April 1, 2008.
    (c) Systems must meet the conditions of paragraph (c)(1) or (2) of
this section for each uncovered finished water storage facility or be
in compliance with a State-approved schedule to meet these conditions
no later than April 1, 2009.
    (1) Systems must cover any uncovered finished water storage
facility.
    (2) Systems must treat the discharge from the uncovered finished
water storage facility to the distribution system to achieve
inactivation and/or removal of at least 4-log virus, 3-log Giardia
lamblia, and 2-log Cryptosporidium using a protocol approved by the
State.
    (d) Failure to comply with the requirements of this section is a
violation of the treatment technique requirement.

Requirements for Microbial Toolbox Components

Sec.  141.715  Microbial toolbox options for meeting Cryptosporidium
treatment requirements.

    (a)(1) Systems receive the treatment credits listed in the table in
paragraph (b) of this section by meeting the conditions for microbial
toolbox options described in Sec. Sec.  141.716 through 141.720.
Systems apply these treatment credits to meet the treatment
requirements in Sec.  141.711 or Sec.  141.712, as applicable.
    (2) Unfiltered systems are eligible for treatment credits for the
microbial toolbox options described in Sec.  141.720 only.
    (b) The following table summarizes options in the microbial
toolbox:

Microbial Toolbox Summary Table: Options, Treatment Credits and Criteria
------------------------------------------------------------------------
                                 Cryptosporidium treatment credit with
        Toolbox Option             design and implementation criteria
------------------------------------------------------------------------
            Source Protection and Management Toolbox Options
------------------------------------------------------------------------
(1) Watershed control program  0.5-log credit for State-approved program
                                comprising required elements, annual
                                program status report to State, and
                                regular watershed survey. Unfiltered
                                systems are not eligible for credit.
                                Specific criteria are in Sec.
                                141.716(a).
(2) Alternative source/intake  No prescribed credit. Systems may conduct
 management.                    simultaneous monitoring for treatment
                                bin classification at alternative intake
                                locations or under alternative intake
                                management strategies. Specific criteria
                                are in Sec.   141.716(b).
------------------------------
                     Pre Filtration Toolbox Options
------------------------------------------------------------------------
(3) Presedimentation basin     0.5-log credit during any month that
 with coagulation.              presedimentation basins achieve a
                                monthly mean reduction of 0.5-log or
                                greater in turbidity or alternative
                                State-approved performance criteria. To
                                be eligible, basins must be operated
                                continuously with coagulant addition and
                                all plant flow must pass through basins.
                                Specific criteria are in Sec.
                                141.717(a).
(4) Two-stage lime softening.  0.5-log credit for two-stage softening
                                where chemical addition and hardness
                                precipitation occur in both stages. All
                                plant flow must pass through both
                                stages. Single-stage softening is
                                credited as equivalent to conventional
                                treatment. Specific criteria are in Sec.
                                  141.717(b).
(5) Bank filtration..........  0.5-log credit for 25-foot setback; 1.0-
                                log credit for 50-foot setback; aquifer
                                must be unconsolidated sand containing
                                at least 10 percent fines; average
                                turbidity in wells must be less than 1
                                NTU. Systems using wells followed by
                                filtration when conducting source water
                                monitoring must sample the well to
                                determine bin classification and are not
                                eligible for additional credit. Specific
                                criteria are in Sec.   141.717(c).
------------------------------
                  Treatment Performance Toolbox Options
------------------------------------------------------------------------
(6) Combined filter            0.5-log credit for combined filter
 performance.                   effluent turbidity less than or equal to
                                0.15 NTU in at least 95 percent of
                                measurements each month. Specific
                                criteria are in Sec.   141.718(a).
(7) Individual filter          0.5-log credit (in addition to 0.5-log
 performance.                   combined filter performance credit) if
                                individual filter effluent turbidity is
                                less than or equal to 0.15 NTU in at
                                least 95 percent of samples each month
                                in each filter and is never greater than
                                0.3 NTU in two consecutive measurements
                                in any filter. Specific criteria are in
                                Sec.   141.718(b).
(8) Demonstration of           Credit awarded to unit process or
 performance.                   treatment train based on a demonstration
                                to the State with a State- approved
                                protocol. Specific criteria are in Sec.
                                 141.718(c).
------------------------------

                  Additional Filtration Toolbox Options
------------------------------------------------------------------------
(9) Bag or cartridge filters   Up to 2-log credit based on the removal
 (individual filters).          efficiency demonstrated during challenge
                                testing with a 1.0-log factor of safety.
                                Specific criteria are in Sec.
                                141.719(a).
(10) Bag or cartridge filters  Up to 2.5-log credit based on the removal
 (in series).                   efficiency demonstrated during challenge
                                testing with a 0.5-log factor of safety.
                                Specific criteria are in Sec.
                                141.719(a).
(11) Membrane filtration.....  Log credit equivalent to removal
                                efficiency demonstrated in challenge
                                test for device if supported by direct
                                integrity testing. Specific criteria are
                                in Sec.   141.719(b).
(12) Second stage filtration.  0.5-log credit for second separate
                                granular media filtration stage if
                                treatment train includes coagulation
                                prior to first filter. Specific criteria
                                are in Sec.   141.719(c)
(13) Slow sand filters.......  2.5-log credit as a secondary filtration
                                step; 3.0-log credit as a primary
                                filtration process. No prior
                                chlorination for either option. Specific
                                criteria are in Sec.   141.719(d).
------------------------------
                      Inactivation Toolbox Options
------------------------------------------------------------------------
(14) Chlorine dioxide........  Log credit based on measured CT in
                                relation to CT table. Specific criteria
                                in Sec.   141.720(b)
(15) Ozone...................  Log credit based on measured CT in
                                relation to CT table. Specific criteria
                                in Sec.   141.720(b).
(16) UV......................  Log credit based on validated UV dose in
                                relation to UV dose table; reactor
                                validation testing required to establish
                                UV dose and associated operating
                                conditions. Specific criteria in Sec.
                                141.720(d).
------------------------------------------------------------------------

Sec.  141.716  Source toolbox components.

    (a) Watershed control program. Systems receive 0.5-log
Cryptosporidium treatment credit for implementing a watershed control
program that meets the requirements of this section.
    (1) Systems that intend to apply for the watershed control program
credit must notify the State of this intent no later than two years
prior to the treatment compliance date applicable to the system in
Sec.  141.713.
    (2) Systems must submit to the State a proposed watershed control
plan no later than one year before the applicable treatment compliance
date in Sec.  141.713. The State must approve the watershed control
plan for the system to receive watershed control program treatment
credit. The watershed control plan must include the elements in
paragraphs (a)(2)(i) through (iv) of this section.
    (i) Identification of an ``area of influence'' outside of which the
likelihood of Cryptosporidium or fecal contamination affecting the
treatment plant intake is not significant. This is the area to be
evaluated in future watershed surveys under paragraph (a)(5)(ii) of
this section.
    (ii) Identification of both potential and actual sources of
Cryptosporidium contamination and an assessment of the relative impact
of these sources on the system's source water quality.
    (iii) An analysis of the effectiveness and feasibility of control
measures that could reduce Cryptosporidium loading from sources of
contamination to the system's source water.
    (iv) A statement of goals and specific actions the system will
undertake to reduce source water Cryptosporidium levels. The plan must
explain how the actions are expected to contribute to specific goals,
identify watershed partners and their roles, identify resource
requirements and commitments, and include a schedule for plan
implementation with deadlines for completing specific actions
identified in the plan.
    (3) Systems with existing watershed control programs (i.e.,
programs in place on January 5, 2006) are eligible to seek this credit.
Their watershed control plans must meet the criteria in paragraph
(a)(2) of this section and must specify ongoing and future actions that
will reduce source water Cryptosporidium levels.
    (4) If the State does not respond to a system regarding approval of
a watershed control plan submitted under this section and the system
meets the other requirements of this section, the watershed control
program will be considered approved and 0.5 log Cryptosporidium
treatment credit will be awarded unless and until the State
subsequently withdraws such approval.
    (5) Systems must complete the actions in paragraphs (a)(5)(i)
through (iii) of this section to maintain the 0.5-log credit.
    (i) Submit an annual watershed control program status report to the
State. The annual watershed control program status report must describe
the system's implementation of the approved plan and assess the
adequacy of the plan to meet its goals. It must explain how the system
is addressing any shortcomings in plan implementation, including those
previously identified by the State or as the result of the watershed
survey conducted under paragraph (a)(5)(ii) of this section. It must
also describe any significant changes that have occurred in the
watershed since the last watershed sanitary survey. If a system
determines during implementation that making a significant change to
its approved watershed control program is necessary, the system must
notify the State prior to making any such changes. If any change is
likely to reduce the level of source water protection, the system must
also list in its notification the actions the system will take to
mitigate this effect.
    (ii) Undergo a watershed sanitary survey every three years for
community water systems and every five years for noncommunity water
systems and submit the survey report to the State. The survey must be
conducted according to State guidelines and by persons the State
approves.
    (A) The watershed sanitary survey must meet the following criteria:
encompass the region identified in the State-approved watershed control
plan as the area of influence; assess the implementation of actions to
reduce source water Cryptosporidium levels; and identify any
significant new sources of Cryptosporidium.
    (B) If the State determines that significant changes may have
occurred in the watershed since the previous watershed sanitary survey,
systems must undergo another watershed sanitary survey by a date the
State requires, which may be earlier than the regular date in paragraph
(a)(5)(ii) of this section.
    (iii) The system must make the watershed control plan, annual
status reports, and watershed sanitary survey reports available to the
public upon

request. These documents must be in a plain language style and include
criteria by which to evaluate the success of the program in achieving
plan goals. The State may approve systems to withhold from the public
portions of the annual status report, watershed control plan, and
watershed sanitary survey based on water supply security
considerations.
    (6) If the State determines that a system is not carrying out the
approved watershed control plan, the State may withdraw the watershed
control program treatment credit.
    (b) Alternative source. (1) A system may conduct source water
monitoring that reflects a different intake location (either in the
same source or for an alternate source) or a different procedure for
the timing or level of withdrawal from the source (alternative source
monitoring). If the State approves, a system may determine its bin
classification under Sec.  141.710 based on the alternative source
monitoring results.
    (2) If systems conduct alternative source monitoring under
paragraph (b)(1) of this section, systems must also monitor their
current plant intake concurrently as described in Sec.  141.701.
    (3) Alternative source monitoring under paragraph (b)(1) of this
section must meet the requirements for source monitoring to determine
bin classification, as described in Sec. Sec.  141.701 through 141.706.
Systems must report the alternative source monitoring results to the
State, along with supporting information documenting the operating
conditions under which the samples were collected.
    (4) If a system determines its bin classification under Sec.
141.710 using alternative source monitoring results that reflect a
different intake location or a different procedure for managing the
timing or level of withdrawal from the source, the system must relocate
the intake or permanently adopt the withdrawal procedure, as
applicable, no later than the applicable treatment compliance date in
Sec.  141.713.

Sec.  141.717  Pre-filtration treatment toolbox components.

    (a) Presedimentation. Systems receive 0.5-log Cryptosporidium
treatment credit for a presedimentation basin during any month the
process meets the criteria in this paragraph.
    (1) The presedimentation basin must be in continuous operation and
must treat the entire plant flow taken from a surface water or GWUDI
source.
    (2) The system must continuously add a coagulant to the
presedimentation basin.
    (3) The presedimentation basin must achieve the performance
criteria in paragraph (3)(i) or (ii) of this section.
    (i) Demonstrates at least 0.5-log mean reduction of influent
turbidity. This reduction must be determined using daily turbidity
measurements in the presedimentation process influent and effluent and
must be calculated as follows: log10(monthly mean of daily
influent turbidity)-log10(monthly mean of daily effluent
turbidity).
    (ii) Complies with State-approved performance criteria that
demonstrate at least 0.5-log mean removal of micron-sized particulate
material through the presedimentation process.
    (b) Two-stage lime softening. Systems receive an additional 0.5-log
Cryptosporidium treatment credit for a two-stage lime softening plant
if chemical addition and hardness precipitation occur in two separate
and sequential softening stages prior to filtration. Both softening
stages must treat the entire plant flow taken from a surface water or
GWUDI source.
    (c) Bank filtration. Systems receive Cryptosporidium treatment
credit for bank filtration that serves as pretreatment to a filtration
plant by meeting the criteria in this paragraph. Systems using bank
filtration when they begin source water monitoring under Sec.
141.701(a) must collect samples as described in Sec.  141.703(d) and
are not eligible for this credit.
    (1) Wells with a ground water flow path of at least 25 feet receive
0.5-log treatment credit; wells with a ground water flow path of at
least 50 feet receive 1.0-log treatment credit. The ground water flow
path must be determined as specified in paragraph (c)(4) of this
section.
    (2) Only wells in granular aquifers are eligible for treatment
credit. Granular aquifers are those comprised of sand, clay, silt, rock
fragments, pebbles or larger particles, and minor cement. A system must
characterize the aquifer at the well site to determine aquifer
properties. Systems must extract a core from the aquifer and
demonstrate that in at least 90 percent of the core length, grains less
than 1.0 mm in diameter constitute at least 10 percent of the core
material.
    (3) Only horizontal and vertical wells are eligible for treatment
credit.
    (4) For vertical wells, the ground water flow path is the measured
distance from the edge of the surface water body under high flow
conditions (determined by the 100 year floodplain elevation boundary or
by the floodway, as defined in Federal Emergency Management Agency
flood hazard maps) to the well screen. For horizontal wells, the ground
water flow path is the measured distance from the bed of the river
under normal flow conditions to the closest horizontal well lateral
screen.
    (5) Systems must monitor each wellhead for turbidity at least once
every four hours while the bank filtration process is in operation. If
monthly average turbidity levels, based on daily maximum values in the
well, exceed 1 NTU, the system must report this result to the State and
conduct an assessment within 30 days to determine the cause of the high
turbidity levels in the well. If the State determines that microbial
removal has been compromised, the State may revoke treatment credit
until the system implements corrective actions approved by the State to
remediate the problem.
    (6) Springs and infiltration galleries are not eligible for
treatment credit under this section, but are eligible for credit under
Sec.  141.718(c).
    (7) Bank filtration demonstration of performance. The State may
approve Cryptosporidium treatment credit for bank filtration based on a
demonstration of performance study that meets the criteria in this
paragraph. This treatment credit may be greater than 1.0-log and may be
awarded to bank filtration that does not meet the criteria in
paragraphs (c)(1)-(5) of this section.
    (i) The study must follow a State-approved protocol and must
involve the collection of data on the removal of Cryptosporidium or a
surrogate for Cryptosporidium and related hydrogeologic and water
quality parameters during the full range of operating conditions.
    (ii) The study must include sampling both from the production
well(s) and from monitoring wells that are screened and located along
the shortest flow path between the surface water source and the
production well(s).

Sec.  141.718  Treatment performance toolbox components.

    (a) Combined filter performance. Systems using conventional
filtration treatment or direct filtration treatment receive an
additional 0.5-log Cryptosporidium treatment credit during any month
the system meets the criteria in this paragraph. Combined filter
effluent (CFE) turbidity must be less than or equal to 0.15 NTU in at
least 95 percent of the measurements. Turbidity must be measured as
described in Sec.  141.74(a) and (c).
    (b) Individual filter performance. Systems using conventional
filtration treatment or direct filtration treatment receive 0.5-log
Cryptosporidium treatment credit, which can be in

addition to the 0.5-log credit under paragraph (a) of this section,
during any month the system meets the criteria in this paragraph.
Compliance with these criteria must be based on individual filter
turbidity monitoring as described in Sec.  141.174 or Sec.  141.560, as
applicable.
    (1) The filtered water turbidity for each individual filter must be
less than or equal to 0.15 NTU in at least 95 percent of the
measurements recorded each month.
    (2) No individual filter may have a measured turbidity greater than
0.3 NTU in two consecutive measurements taken 15 minutes apart.
    (3) Any system that has received treatment credit for individual
filter performance and fails to meet the requirements of paragraph
(b)(1) or (2) of this section during any month does not receive a
treatment technique violation under Sec.  141.711(c) if the State
determines the following:
    (i) The failure was due to unusual and short-term circumstances
that could not reasonably be prevented through optimizing treatment
plant design, operation, and maintenance.
    (ii) The system has experienced no more than two such failures in
any calendar year.
    (c) Demonstration of performance. The State may approve
Cryptosporidium treatment credit for drinking water treatment processes
based on a demonstration of performance study that meets the criteria
in this paragraph. This treatment credit may be greater than or less
than the prescribed treatment credits in Sec.  141.711 or Sec. Sec.
141.717 through 141.720 and may be awarded to treatment processes that
do not meet the criteria for the prescribed credits.
    (1) Systems cannot receive the prescribed treatment credit for any
toolbox box option in Sec. Sec.  141.717 through 141.720 if that
toolbox option is included in a demonstration of performance study for
which treatment credit is awarded under this paragraph.
    (2) The demonstration of performance study must follow a State-
approved protocol and must demonstrate the level of Cryptosporidium
reduction the treatment process will achieve under the full range of
expected operating conditions for the system.
    (3) Approval by the State must be in writing and may include
monitoring and treatment performance criteria that the system must
demonstrate and report on an ongoing basis to remain eligible for the
treatment credit. The State may designate such criteria where necessary
to verify that the conditions under which the demonstration of
performance credit was approved are maintained during routine
operation.

Sec.  141.719  Additional filtration toolbox components.

    (a) Bag and cartridge filters. Systems receive Cryptosporidium
treatment credit of up to 2.0-log for individual bag or cartridge
filters and up to 2.5-log for bag or cartridge filters operated in
series by meeting the criteria in paragraphs (a)(1) through (10) of
this section. To be eligible for this credit, systems must report the
results of challenge testing that meets the requirements of paragraphs
(a)(2) through (9) of this section to the State. The filters must treat
the entire plant flow taken from a subpart H source.
    (1) The Cryptosporidium treatment credit awarded to bag or
cartridge filters must be based on the removal efficiency demonstrated
during challenge testing that is conducted according to the criteria in
paragraphs (a)(2) through (a)(9) of this section. A factor of safety
equal to 1-log for individual bag or cartridge filters and 0.5-log for
bag or cartridge filters in series must be applied to challenge testing
results to determine removal credit. Systems may use results from
challenge testing conducted prior to January 5, 2006 if the prior
testing was consistent with the criteria specified in paragraphs (a)(2)
through (9) of this section.
    (2) Challenge testing must be performed on full-scale bag or
cartridge filters, and the associated filter housing or pressure
vessel, that are identical in material and construction to the filters
and housings the system will use for removal of Cryptosporidium. Bag or
cartridge filters must be challenge tested in the same configuration
that the system will use, either as individual filters or as a series
configuration of filters.
    (3) Challenge testing must be conducted using Cryptosporidium or a
surrogate that is removed no more efficiently than Cryptosporidium. The
microorganism or surrogate used during challenge testing is referred to
as the challenge particulate. The concentration of the challenge
particulate must be determined using a method capable of discreetly
quantifying the specific microorganism or surrogate used in the test;
gross measurements such as turbidity may not be used.
    (4) The maximum feed water concentration that can be used during a
challenge test must be based on the detection limit of the challenge
particulate in the filtrate (i.e., filtrate detection limit) and must
be calculated using the following equation:

Maximum Feed Concentration = 1 x 10 4 x (Filtrate Detection
Limit)

    (5) Challenge testing must be conducted at the maximum design flow
rate for the filter as specified by the manufacturer.
    (6) Each filter evaluated must be tested for a duration sufficient
to reach 100 percent of the terminal pressure drop, which establishes
the maximum pressure drop under which the filter may be used to comply
with the requirements of this subpart.
    (7) Removal efficiency of a filter must be determined from the
results of the challenge test and expressed in terms of log removal
values using the following equation:

LRV = LOG10(Cf)-LOG10(Cp)

Where:
LRV = log removal value demonstrated during challenge testing;
Cf = the feed concentration measured during the challenge
test; and Cp = the filtrate concentration measured during
the challenge test. In applying this equation, the same units must be
used for the feed and filtrate concentrations. If the challenge
particulate is not detected in the filtrate, then the term
Cp must be set equal to the detection limit.

    (8) Each filter tested must be challenged with the challenge
particulate during three periods over the filtration cycle: within two
hours of start-up of a new filter; when the pressure drop is between 45
and 55 percent of the terminal pressure drop; and at the end of the
cycle after the pressure drop has reached 100 percent of the terminal
pressure drop. An LRV must be calculated for each of these challenge
periods for each filter tested. The LRV for the filter
(LRVfilter) must be assigned the value of the minimum LRV
observed during the three challenge periods for that filter.
    (9) If fewer than 20 filters are tested, the overall removal
efficiency for the filter product line must be set equal to the lowest
LRVfilter among the filters tested. If 20 or more filters
are tested, the overall removal efficiency for the filter product line
must be set equal to the 10th percentile of the set of
LRVfilter values for the various filters tested. The
percentile is defined by (i/(n+1)) where i is the rank of n individual
data points ordered lowest to highest. If necessary, the 10th
percentile may be calculated using linear interpolation.
    (10) If a previously tested filter is modified in a manner that
could change the removal efficiency of the filter product line,
challenge testing to demonstrate the removal efficiency of

the modified filter must be conducted and submitted to the State.
    (b) Membrane filtration. (1) Systems receive Cryptosporidium
treatment credit for membrane filtration that meets the criteria of
this paragraph. Membrane cartridge filters that meet the definition of
membrane filtration in Sec.  141.2 are eligible for this credit. The
level of treatment credit a system receives is equal to the lower of
the values determined under paragraph (b)(1)(i) and (ii) of this
section.
    (i) The removal efficiency demonstrated during challenge testing
conducted under the conditions in paragraph (b)(2) of this section.
    (ii) The maximum removal efficiency that can be verified through
direct integrity testing used with the membrane filtration process
under the conditions in paragraph (b)(3) of this section.
    (2) Challenge Testing. The membrane used by the system must undergo
challenge testing to evaluate removal efficiency, and the system must
report the results of challenge testing to the State. Challenge testing
must be conducted according to the criteria in paragraphs (b)(2)(i)
through (vii) of this section. Systems may use data from challenge
testing conducted prior to January 5, 2006 if the prior testing was
consistent with the criteria in paragraphs (b)(2)(i) through (vii) of
this section.
    (i) Challenge testing must be conducted on either a full-scale
membrane module, identical in material and construction to the membrane
modules used in the system's treatment facility, or a smaller-scale
membrane module, identical in material and similar in construction to
the full-scale module. A module is defined as the smallest component of
a membrane unit in which a specific membrane surface area is housed in
a device with a filtrate outlet structure.
    (ii) Challenge testing must be conducted using Cryptosporidium
oocysts or a surrogate that is removed no more efficiently than
Cryptosporidium oocysts. The organism or surrogate used during
challenge testing is referred to as the challenge particulate. The
concentration of the challenge particulate, in both the feed and
filtrate water, must be determined using a method capable of discretely
quantifying the specific challenge particulate used in the test; gross
measurements such as turbidity may not be used.
    (iii) The maximum feed water concentration that can be used during
a challenge test is based on the detection limit of the challenge
particulate in the filtrate and must be determined according to the
following equation:

Maximum Feed Concentration = 3.16 x 106 x (Filtrate
Detection Limit)

    (iv) Challenge testing must be conducted under representative
hydraulic conditions at the maximum design flux and maximum design
process recovery specified by the manufacturer for the membrane module.
Flux is defined as the throughput of a pressure driven membrane process
expressed as flow per unit of membrane area. Recovery is defined as the
volumetric percent of feed water that is converted to filtrate over the
course of an operating cycle uninterrupted by events such as chemical
cleaning or a solids removal process (i.e., backwashing).
    (v) Removal efficiency of a membrane module must be calculated from
the challenge test results and expressed as a log removal value
according to the following equation:

LRV = LOG10(Cf) x LOG10(Cp)

Where:
LRV = log removal value demonstrated during the challenge test;
Cf = the feed concentration measured during the challenge
test; and Cp = the filtrate concentration measured during
the challenge test. Equivalent units must be used for the feed and
filtrate concentrations. If the challenge particulate is not detected
in the filtrate, the term Cp is set equal to the detection
limit for the purpose of calculating the LRV. An LRV must be calculated
for each membrane module evaluated during the challenge test.

    (vi) The removal efficiency of a membrane filtration process
demonstrated during challenge testing must be expressed as a log
removal value (LRVC-Test). If fewer than 20 modules are
tested, then LRVC-Test is equal to the lowest of the
representative LRVs among the modules tested. If 20 or more modules are
tested, then LRVC-Test is equal to the 10th percentile of
the representative LRVs among the modules tested. The percentile is
defined by (i/(n+1)) where i is the rank of n individual data points
ordered lowest to highest. If necessary, the 10th percentile may be
calculated using linear interpolation.
    (vii) The challenge test must establish a quality control release
value (QCRV) for a non-destructive performance test that demonstrates
the Cryptosporidium removal capability of the membrane filtration
module. This performance test must be applied to each production
membrane module used by the system that was not directly challenge
tested in order to verify Cryptosporidium removal capability.
Production modules that do not meet the established QCRV are not
eligible for the treatment credit demonstrated during the challenge
test.
    (viii) If a previously tested membrane is modified in a manner that
could change the removal efficiency of the membrane or the
applicability of the non-destructive performance test and associated
QCRV, additional challenge testing to demonstrate the removal
efficiency of, and determine a new QCRV for, the modified membrane must
be conducted and submitted to the State.
    (3) Direct integrity testing. Systems must conduct direct integrity
testing in a manner that demonstrates a removal efficiency equal to or
greater than the removal credit awarded to the membrane filtration
process and meets the requirements described in paragraphs (b)(3)(i)
through (vi) of this section. A direct integrity test is defined as a
physical test applied to a membrane unit in order to identify and
isolate integrity breaches (i.e., one or more leaks that could result
in contamination of the filtrate).
    (i) The direct integrity test must be independently applied to each
membrane unit in service. A membrane unit is defined as a group of
membrane modules that share common valving that allows the unit to be
isolated from the rest of the system for the purpose of integrity
testing or other maintenance.
    (ii) The direct integrity method must have a resolution of 3
micrometers or less, where resolution is defined as the size of the
smallest integrity breach that contributes to a response from the
direct integrity test.
    (iii) The direct integrity test must have a sensitivity sufficient
to verify the log treatment credit awarded to the membrane filtration
process by the State, where sensitivity is defined as the maximum log
removal value that can be reliably verified by a direct integrity test.
Sensitivity must be determined using the approach in either paragraph
(b)(3)(iii)(A) or (B) of this section as applicable to the type of
direct integrity test the system uses.
    (A) For direct integrity tests that use an applied pressure or
vacuum, the direct integrity test sensitivity must be calculated
according to the following equation:

LRVDIT = LOG10 (Qp /(VCF x
Qbreach))

Where:
LRVDIT = the sensitivity of the direct integrity test;
Qp = total design filtrate flow from the membrane unit;
Qbreach = flow of water from an

integrity breach associated with the smallest integrity test response
that can be reliably measured, and VCF = volumetric concentration
factor. The volumetric concentration factor is the ratio of the
suspended solids concentration on the high pressure side of the
membrane relative to that in the feed water.

    (B) For direct integrity tests that use a particulate or molecular
marker, the direct integrity test sensitivity must be calculated
according to the following equation:

LRVDIT = LOG10(Cf)-
LOG10(Cp)

Where:
LRVDIT = the sensitivity of the direct integrity test;
Cf = the typical feed concentration of the marker used in
the test; and Cp = the filtrate concentration of the marker
from an integral membrane unit.

    (iv) Systems must establish a control limit within the sensitivity
limits of the direct integrity test that is indicative of an integral
membrane unit capable of meeting the removal credit awarded by the
State.
    (v) If the result of a direct integrity test exceeds the control
limit established under paragraph (b)(3)(iv) of this section, the
system must remove the membrane unit from service. Systems must conduct
a direct integrity test to verify any repairs, and may return the
membrane unit to service only if the direct integrity test is within
the established control limit.
    (vi) Systems must conduct direct integrity testing on each membrane
unit at a frequency of not less than once each day that the membrane
unit is in operation. The State may approve less frequent testing,
based on demonstrated process reliability, the use of multiple barriers
effective for Cryptosporidium, or reliable process safeguards.
    (4) Indirect integrity monitoring. Systems must conduct continuous
indirect integrity monitoring on each membrane unit according to the
criteria in paragraphs (b)(4)(i) through (v) of this section. Indirect
integrity monitoring is defined as monitoring some aspect of filtrate
water quality that is indicative of the removal of particulate matter.
A system that implements continuous direct integrity testing of
membrane units in accordance with the criteria in paragraphs (b)(3)(i)
through (v) of this section is not subject to the requirements for
continuous indirect integrity monitoring. Systems must submit a monthly
report to the State summarizing all continuous indirect integrity
monitoring results triggering direct integrity testing and the
corrective action that was taken in each case.
    (i) Unless the State approves an alternative parameter, continuous
indirect integrity monitoring must include continuous filtrate
turbidity monitoring.
    (ii) Continuous monitoring must be conducted at a frequency of no
less than once every 15 minutes.
    (iii) Continuous monitoring must be separately conducted on each
membrane unit.
    (iv) If indirect integrity monitoring includes turbidity and if the
filtrate turbidity readings are above 0.15 NTU for a period greater
than 15 minutes (i.e., two consecutive 15-minute readings above 0.15
NTU), direct integrity testing must immediately be performed on the
associated membrane unit as specified in paragraphs (b)(3)(i) through
(v) of this section.
    (v) If indirect integrity monitoring includes a State-approved
alternative parameter and if the alternative parameter exceeds a State-
approved control limit for a period greater than 15 minutes, direct
integrity testing must immediately be performed on the associated
membrane units as specified in paragraphs (b)(3)(i) through (v) of this
section.
    (c) Second stage filtration. Systems receive 0.5-log
Cryptosporidium treatment credit for a separate second stage of
filtration that consists of sand, dual media, GAC, or other fine grain
media following granular media filtration if the State approves. To be
eligible for this credit, the first stage of filtration must be
preceded by a coagulation step and both filtration stages must treat
the entire plant flow taken from a surface water or GWUDI source. A
cap, such as GAC, on a single stage of filtration is not eligible for
this credit. The State must approve the treatment credit based on an
assessment of the design characteristics of the filtration process.
    (d) Slow sand filtration (as secondary filter). Systems are
eligible to receive 2.5-log Cryptosporidium treatment credit for a slow
sand filtration process that follows a separate stage of filtration if
both filtration stages treat entire plant flow taken from a surface
water or GWUDI source and no disinfectant residual is present in the
influent water to the slow sand filtration process. The State must
approve the treatment credit based on an assessment of the design
characteristics of the filtration process. This paragraph does not
apply to treatment credit awarded to slow sand filtration used as a
primary filtration process.

Sec.  141.720  Inactivation toolbox components.

    (a) Calculation of CT values. (1) CT is the product of the
disinfectant contact time (T, in minutes) and disinfectant
concentration (C, in milligrams per liter). Systems with treatment
credit for chlorine dioxide or ozone under paragraph (b) or (c) of this
section must calculate CT at least once each day, with both C and T
measured during peak hourly flow as specified in Sec. Sec.  141.74(a)
through (b).
    (2) Systems with several disinfection segments in sequence may
calculate CT for each segment, where a disinfection segment is defined
as a treatment unit process with a measurable disinfectant residual
level and a liquid volume. Under this approach, systems must add the
Cryptosporidium CT values in each segment to determine the total CT for
the treatment plant.
    (b) CT values for chlorine dioxide and ozone. (1) Systems receive
the Cryptosporidium treatment credit listed in this table by meeting
the corresponding chlorine dioxide CT value for the applicable water
temperature, as described in paragraph (a) of this section.

                                  CT Values (mg[middot]min/L) for Cryptosporidium Inactivation by Chlorine Dioxide \1\
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                Water Temperature, [deg]C
                           Log credit                            ---------------------------------------------------------------------------------------
                                                                   < =0.5     1       2       3       5       7      10      15      20      25      30
--------------------------------------------------------------------------------------------------------------------------------------------------------
(i) 0.25........................................................     159     153     140     128     107      90      69      45      29      19      12
(ii) 0.5........................................................     319     305     279     256     214     180     138      89      58      38      24
(iii) 1.0.......................................................     637     610     558     511     429     360     277     179     116      75      49
(iv) 1.5........................................................     956     915     838     767     643     539     415     268     174     113      73
(v) 2.0.........................................................    1275    1220    1117    1023     858     719     553     357     232     150      98
(vi) 2.5........................................................    1594    1525    1396    1278    1072     899     691     447     289     188     122

(vii) 3.0.......................................................    1912    1830    1675    1534    1286    1079     830     536     347     226    147
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Systems may use this equation to determine log credit between the indicated values: Log credit = (0.001506 x (1.09116) Temp) x CT.

    (2) Systems receive the Cryptosporidium treatment credit listed in
this table by meeting the corresponding ozone CT values for the
applicable water temperature, as described in paragraph (a) of this
section.

                                        CT Values (mg[middot]min/L) for Cryptosporidium Inactivation by Ozone \1\
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                Water Temperature, [deg]C
                           Log credit                            ---------------------------------------------------------------------------------------
                                                                   < =0.5     1       2       3       5       7      10      15      20      25      30
--------------------------------------------------------------------------------------------------------------------------------------------------------
(i) 0.25........................................................     6.0     5.8     5.2     4.8     4.0     3.3     2.5     1.6     1.0     0.6    0.39
(ii) 0.5........................................................      12      12      10     9.5     7.9     6.5     4.9     3.1     2.0     1.2    0.78
(iii) 1.0.......................................................      24      23      21      19      16      13     9.9     6.2     3.9     2.5     1.6
(iv) 1.5........................................................      36      35      31      29      24      20      15     9.3     5.9     3.7     2.4
(v) 2.0.........................................................      48      46      42      38      32      26      20      12     7.8     4.9     3.1
(vi) 2.5........................................................      60      58      52      48      40      33      25      16     9.8     6.2     3.9
(vii) 3.0.......................................................      72      69      63      57      47      39      30      19      12     7.4    4.7
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Systems may use this equation to determine log credit between the indicated values: Log credit = (0.0397 x (1.09757)Temp) x CT.

    (c) Site-specific study. The State may approve alternative chlorine
dioxide or ozone CT values to those listed in paragraph (b) of this
section on a site-specific basis. The State must base this approval on
a site-specific study a system conducts that follows a State-approved
protocol.
    (d) Ultraviolet light. Systems receive Cryptosporidium, Giardia
lamblia, and virus treatment credits for ultraviolet (UV) light
reactors by achieving the corresponding UV dose values shown in
paragraph (d)(1) of this section. Systems must validate and monitor UV
reactors as described in paragraphs (d)(2) and (3) of this section to
demonstrate that they are achieving a particular UV dose value for
treatment credit.
    (1) UV dose table. The treatment credits listed in this table are
for UV light at a wavelength of 254 nm as produced by a low pressure
mercury vapor lamp. To receive treatment credit for other lamp types,
systems must demonstrate an equivalent germicidal dose through reactor
validation testing, as described in paragraph (d)(2) of this section.
The UV dose values in this table are applicable only to post-filter
applications of UV in filtered systems and to unfiltered systems.

                UV Dose Table for Cryptosporidium, Giardia lamblia, and Virus Inactivation Credit
----------------------------------------------------------------------------------------------------------------
                                                          Cryptosporidium    Giardia lamblia
                       Log credit                           UV dose (mJ/       UV dose (mJ/      Virus  UV dose
                                                               cm\2\)             cm\2\)           (mJ/cm\2\)
----------------------------------------------------------------------------------------------------------------
(i) 0.5................................................                1.6                1.5                 39
(ii) 1.0...............................................                2.5                2.1                 58
(iii) 1.5..............................................                3.9                3.0                 79
(iv) 2.0...............................................                5.8                5.2                100
(v) 2.5................................................                8.5                7.7                121
(vi) 3.0...............................................                 12                 11                143
(vii) 3.5..............................................                 15                 15                163
(viii) 4.0.............................................                 22                 22                186
----------------------------------------------------------------------------------------------------------------

    (2) Reactor validation testing. Systems must use UV reactors that
have undergone validation testing to determine the operating conditions
under which the reactor delivers the UV dose required in paragraph
(d)(1) of this section (i.e., validated operating conditions). These
operating conditions must include flow rate, UV intensity as measured
by a UV sensor, and UV lamp status.
    (i) When determining validated operating conditions, systems must
account for the following factors: UV absorbance of the water; lamp
fouling and aging; measurement uncertainty of on-line sensors; UV dose
distributions arising from the velocity profiles through the reactor;
failure of UV lamps or other critical system components; and inlet and
outlet piping or channel configurations of the UV reactor.
    (ii) Validation testing must include the following: Full scale
testing of a reactor that conforms uniformly to the UV reactors used by
the system and inactivation of a test microorganism whose dose response
characteristics have been quantified with a low pressure mercury vapor
lamp.
    (iii) The State may approve an alternative approach to validation
testing.
    (3) Reactor monitoring. (i) Systems must monitor their UV reactors
to determine if the reactors are operating within validated conditions,
as determined under paragraph (d)(2) of this section. This monitoring
must include UV intensity as measured by a UV sensor, flow rate, lamp
status, and other parameters the State designates

based on UV reactor operation. Systems must verify the calibration of
UV sensors and must recalibrate sensors in accordance with a protocol
the State approves.
    (ii) To receive treatment credit for UV light, systems must treat
at least 95 percent of the water delivered to the public during each
month by UV reactors operating within validated conditions for the
required UV dose, as described in paragraphs (d)(1) and (2) of this
section. Systems must demonstrate compliance with this condition by the
monitoring required under paragraph (d)(3)(i) of this section.

Reporting and Recordkeeping Requirements

Sec.  141.721  Reporting requirements.

    (a) Systems must report sampling schedules under Sec.  141.702 and
source water monitoring results under Sec.  141.706 unless they notify
the State that they will not conduct source water monitoring due to
meeting the criteria of Sec.  141.701(d).
    (b) Systems must report the use of uncovered finished water storage
facilities to the State as described in Sec.  141.714.
    (c) Filtered systems must report their Cryptosporidium bin
classification as described in Sec.  141.710.
    (d) Unfiltered systems must report their mean source water
Cryptosporidium level as described in Sec.  141.712.
    (e) Systems must report disinfection profiles and benchmarks to the
State as described in Sec. Sec.  141.708 through 141.709 prior to
making a significant change in disinfection practice.
    (f) Systems must report to the State in accordance with the
following table for any microbial toolbox options used to comply with
treatment requirements under Sec.  141.711 or Sec.  141.712.
Alternatively, the State may approve a system to certify operation
within required parameters for treatment credit rather than reporting
monthly operational data for toolbox options.

                                    Microbial Toolbox Reporting Requirements
----------------------------------------------------------------------------------------------------------------
                                                    Systems must submit the
                Toolbox option                       following information          On the following schedule
----------------------------------------------------------------------------------------------------------------
(1) Watershed control program (WCP)..........  (i) Notice of intention to        No later than two years before
                                                develop a new or continue an      the applicable treatment
                                                existing watershed control        compliance date in Sec.
                                                program.                          141.713
                                               (ii) Watershed control plan.....  No later than one year before
                                                                                the applicable treatment
                                                                                compliance date in Sec.
                                                                                141.713.
                                               (iii) Annual watershed control    Every 12 months, beginning one
                                                program status report.            year after the applicable
                                                                                treatment compliance date in
                                                                                Sec.   141.713.
                                               (iv) Watershed sanitary survey    For community water systems,
                                                report.                           every three years beginning
                                                                                three years after the
                                                                                applicable treatment
                                                                                compliance date in Sec.
                                                                                141.713. For noncommunity
                                                                                water systems, every five
                                                                                years beginning five years
                                                                                after the applicable treatment
                                                                                compliance date in Sec.
                                                                                141.713.
(2) Alternative source/intake management.....  Verification that system has      No later than the applicable
                                                relocated the intake or adopted   treatment compliance date in
                                                the intake withdrawal procedure   Sec.   141.713.
                                                reflected in monitoring results.
(3) Presedimentation.........................  Monthly verification of the       Monthly reporting within 10
                                                following: (i) Continuous basin   days following the month in
                                                operation (ii) Treatment of       which the monitoring was
                                                100% of the flow (iii)            conducted, beginning on the
                                                Continuous addition of a          applicable treatment
                                                coagulant (iv) At least 0.5-log   compliance date in Sec.
                                                mean reduction of influent        141.713.
                                                turbidity or compliance with
                                                alternative State-approved
                                                performance criteria.
(4) Two-stage lime softening.................  Monthly verification of the       Monthly reporting within 10
                                                following: (i) Chemical           days following the month in
                                                addition and hardness             which the monitoring was
                                                precipitation occurred in two     conducted, beginning on the
                                                separate and sequential           applicable treatment
                                                softening stages prior to         compliance date in Sec.
                                                filtration (ii) Both stages       141.713.
                                                treated 100% of the plant flow.
(5) Bank filtration..........................  (i) Initial demonstration of the  No later than the applicable
                                                following: (A) Unconsolidated,    treatment compliance date in
                                                predominantly sandy aquifer (B)   Sec.   141.713.
                                                Setback distance of at least 25
                                                ft. (0.5-log credit) or 50 ft.
                                                (1.0-log credit).
                                               (ii) If monthly average of daily  Report within 30 days following
                                                max turbidity is greater than 1   the month in which the
                                                NTU then system must report       monitoring was conducted,
                                                result and submit an assessment   beginning on the applicable
                                                of the cause..                    treatment compliance date in
                                                                                Sec.   141.713.
(6) Combined filter performance..............  Monthly verification of combined  Monthly reporting within 10
                                                filter effluent (CFE) turbidity   days following the month in
                                                levels less than or equal to      which the monitoring was
                                                0.15 NTU in at least 95 percent   conducted, beginning on the
                                                of the 4 hour CFE measurements    applicable treatment
                                                taken each month.                 compliance date in Sec.
                                                                                141.713.
(7) Individual filter performance............  Monthly verification of the       Monthly reporting within 10
                                                following: (i) Individual         days following the month in
                                                filter effluent (IFE )            which the monitoring was
                                                turbidity levels less than or     conducted, beginning on the
                                                equal to 0.15 NTU in at least     applicable treatment
                                                95 percent of samples each        compliance date in Sec.
                                                month in each filter (ii) No      141.713.]
                                                individual filter greater than
                                                0.3 NTU in two consecutive
                                                readings 15 minutes apart.
(8) Demonstration of performance.............  (i) Results from testing          No later than the applicable
                                                following a State approved        treatment compliance date in
                                                protocol.                         Sec.   141.713.
                                               (ii) As required by the State,    Within 10 days following the
                                                monthly verification of           month in which monitoring was
                                                operation within conditions of    conducted, beginning on the
                                                State approval for                applicable treatment
                                                demonstration of performance      compliance date in Sec.
                                                credit.                           141.713.

(9) Bag filters and cartridge filters........  (i) Demonstration that the        No later than the applicable
                                                following criteria are met: (A)   treatment compliance date in
                                                Process meets the definition of   Sec.   141.713.
                                                bag or cartridge filtration;
                                                (B) Removal efficiency
                                                established through challenge
                                                testing that meets criteria in
                                                this subpart.
                                               (ii) Monthly verification that    Within 10 days following the
                                                100% of plant flow was filtered.  month in which monitoring was
                                                                                conducted, beginning on the
                                                                                applicable treatment
                                                                                compliance date in Sec.
                                                                                141.713.
(10) Membrane filtration.....................  (i) Results of verification       No later than the applicable
                                                testing demonstrating the         treatment compliance date in
                                                following: (A) Removal            Sec.   141.713.
                                                efficiency established through
                                                challenge testing that meets
                                                criteria in this subpart; (B)
                                                Integrity test method and
                                                parameters, including
                                                resolution, sensitivity, test
                                                frequency, control limits, and
                                                associated baseline.
                                               (ii) Monthly report summarizing   Within 10 days following the
                                                the following: (A) All direct     month in which monitoring was
                                                integrity tests above the         conducted, beginning on the
                                                control limit; (B) If             applicable treatment
                                                applicable, any turbidity or      compliance date in Sec.
                                                alternative state-approved        141.713.
                                                indirect integrity monitoring
                                                results triggering direct
                                                integrity testing and the
                                                corrective action that was
                                                taken.
(11) Second stage filtration.................  Monthly verification that 100%    Within 10 days following the
                                                of flow was filtered through      month in which monitoring was
                                                both stages and that first        conducted, beginning on the
                                                stage was preceded by             applicable treatment
                                                coagulation step.                 compliance date in Sec.
                                                                                141.713.
(12) Slow sand filtration (as secondary        Monthly verification that both a  Within 10 days following the
 filter).                                       slow sand filter and a            month in which monitoring was
                                                preceding separate stage of       conducted, beginning on the
                                                filtration treated 100% of flow   applicable treatment
                                                from subpart H sources..          compliance date in Sec.
                                                                                141.713.
(13) Chlorine dioxide........................  Summary of CT values for each     Within 10 days following the
                                                day as described in Sec.          month in which monitoring was
                                                141.720..                         conducted, beginning on the
                                                                                applicable treatment
                                                                                compliance date in Sec.
                                                                                141.713.
(14) Ozone...................................  Summary of CT values for each     Within 10 days following the
                                                day as described in Sec.          month in which monitoring was
                                                141.720..                         conducted, beginning on the
                                                                                applicable treatment
                                                                                compliance date in Sec.
                                                                                141.713.
(15) UV......................................  (i) Validation test results       No later than the applicable
                                                demonstrating operating           treatment compliance date in
                                                conditions that achieve           Sec.   141.713.
                                                required UV dose.                Within 10 days following the
                                               (ii) Monthly report summarizing    month in which monitoring was
                                                the percentage of water           conducted, beginning on the
                                                entering the distribution         applicable treatment
                                                system that was not treated by    compliance date in Sec.
                                                UV reactors operating within      141.713.
                                                validated conditions for the
                                                required dose as specified in
                                                141.720(d)..
----------------------------------------------------------------------------------------------------------------

Sec.  141.722  Recordkeeping requirements.

    (a) Systems must keep results from the initial round of source
water monitoring under Sec.  141.701(a) and the second round of source
water monitoring under Sec.  141.701(b) until 3 years after bin
classification under Sec.  141.710 for filtered systems or
determination of the mean Cryptosporidium level under Sec.  141.710 for
unfiltered systems for the particular round of monitoring.
    (b) Systems must keep any notification to the State that they will
not conduct source water monitoring due to meeting the criteria of
Sec.  141.701(d) for 3 years.
    (c) Systems must keep the results of treatment monitoring
associated with microbial toolbox options under Sec. Sec.  141.716
through 141.720 and with uncovered finished water reservoirs under
Sec.  141.714, as applicable, for 3 years.

Requirements for Sanitary Surveys Performed by EPA

Sec.  141.723  Requirements to respond to significant deficiencies
identified in sanitary surveys performed by EPA.

    (a) A sanitary survey is an onsite review of the water source
(identifying sources of contamination by using results of source water
assessments where available), facilities, equipment, operation,
maintenance, and monitoring compliance of a PWS to evaluate the
adequacy of the PWS, its sources and operations, and the distribution
of safe drinking water.
    (b) For the purposes of this section, a significant deficiency
includes a defect in design, operation, or maintenance, or a failure or
malfunction of the sources, treatment, storage, or distribution system
that EPA determines to be causing, or has the potential for causing the
introduction of contamination into the water delivered to consumers.
    (c) For sanitary surveys performed by EPA, systems must respond in
writing to significant deficiencies identified in sanitary survey
reports no later than 45 days after receipt of the report, indicating
how and on what schedule the system will address significant
deficiencies noted in the survey.
    (d) Systems must correct significant deficiencies identified in
sanitary survey reports according to the schedule approved by EPA, or
if there is no approved schedule, according to the schedule reported
under paragraph (c) of this section if such deficiencies are within the
control of the system.

PART 142--NATIONAL PRIMARY DRINKING WATER REGULATIONS
IMPLEMENTATION

0
8. The authority citation for part 142 continues to read as follows:

    Authority: 42 U.S.C. 300f, 300g-1, 300g-2, 300g-3, 300g-4, 300g-
5, 300g-6, 300j-4, 300j-9 and 300j-11.

0
9. Section 142.14 is amended by adding paragraph (a)(9) to read as
follows:

Sec.  142.14  Records kept by States.

* * * * *
    (a) * * *

    (9) Any decisions made pursuant to the provisions of part 141,
subpart W of this chapter.
    (i) Results of source water E. coli and Cryptosporidium monitoring.
    (ii) The bin classification after the initial and after the second
round of source water monitoring for each filtered system, as described
in Sec.  141.710 of this chapter.
    (iii) Any change in treatment requirements for filtered systems due
to watershed assessment during sanitary surveys, as described in Sec.
141.711(d) of this chapter.
    (iv) The determination of whether the mean Cryptosporidium level is
greater than 0.01 oocysts/L after the initial and after the second
round of source water monitoring for each unfiltered system, as
described in Sec.  141.712(a) of this chapter.
    (v) The treatment processes or control measures that systems use to
meet their Cryptosporidium treatment requirements under Sec.  141.711
or Sec.  141.712 of this chapter.
    (vi) A list of systems required to cover or treat the effluent of
an uncovered finished water storage facility, as specified in Sec.
141.714 of this chapter.
* * * * *

0
10. Section 142.15 is amended by adding paragraph (c)(6) to read as
follows:

Sec.  142.15  Reports by States.

    (c) * * *
    (6) Subpart W. (i) The bin classification after the initial and
after the second round of source water monitoring for each filtered
system, as described in Sec.  141.710 of this chapter.
    (ii) Any change in treatment requirements for these systems due to
watershed assessment during sanitary surveys, as described in Sec.
141.711(d) of this chapter.
    (iii) The determination of whether the mean Cryptosporidium level
is greater than 0.01 oocysts/L both after the initial and after the
second round of source water monitoring for each unfiltered system, as
described in Sec.  141.712(a) of this chapter.
* * * * *

0
11. Section 142.16 is amended by adding paragraph (n) to read as
follows:

Sec.  142.16  Special primacy conditions.

* * * * *
    (n) Requirements for States to adopt 40 CFR part 141, subpart W. In
addition to the general primacy requirements elsewhere in this part,
including the requirements that State regulations be at least as
stringent as Federal requirements, an application for approval of a
State program revision that adopts 40 CFR part 141, subpart W, must
contain a description of how the State will accomplish the following
program requirements where allowed in State programs.
    (1) Approve an alternative to the E. coli levels that trigger
Cryptosporidium monitoring by filtered systems serving fewer than
10,000 people, as described in Sec.  141.701(a)(5).
    (2) Assess significant changes in the watershed and source water as
part of the sanitary survey process and determine appropriate follow-up
action for systems, as described in Sec.  141.711(d) of this chapter.
    (3) Approve watershed control programs for the 0.5-log treatment
credit in the microbial toolbox, as described in Sec.  141.716(a) of
this chapter.
    (4) Approve protocols for demonstration of performance treatment
credits in the microbial toolbox, as allowed under Sec.  141.718(c) of
this chapter.
    (5) Approve protocols for alternative ozone and chlorine dioxide CT
values in the microbial toolbox, as allowed under Sec.  141.720(c) of
this chapter.
    (6) Approve an alternative approach to UV reactor validation
testing in the microbial toolbox, as allowed under Sec.
141.720(d)(2)(iii) of this chapter.
* * * * *
[FR Doc. 06-4 Filed 1-4-06; 8:45 am]

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