### 484 40 CFR Ch. I (7–1–12 Edition) § 141.76

with the primacy agency as soon as practical, but no later than 24 hoursafter the exceedance is known, in accordance with the public notification requirements under §141.203(b)(3).

(iii) If at any time the residual falls below 0.2 mg/l in the water entering the distribution system, the system must notify the State as soon as possible, but no later than by the end of the nextbusiness day. The system also must notify the State by the end of the nextbusiness day whether or not the residual was restored to at least 0.2 mg/l
within 4 hours.

[54 FR 27527, June 29, 1989, as amended at 65 FR 26022, May 4, 2000; 69 FR 38856, June 29, 2004]

§ 141.76 Recycle provisions.

(a) Applicability. All subpart H systems that employ conventional filtration or direct filtration treatment and that recycle spent filter backwashwater, thickener supernatant, or liquids from dewatering processes must meet the requirements in paragraphs (b) through (d) of this section.

(b) Reporting. A system must notify the State in writing by Decemeber 8, 2003, if the system recycles spent filterbackwash water, thickener supernatant, or liquids from dewateringprocesses. This notification must include, at a minimum, the information specified in paragraphs (b)(1) and (2) of
this section.

(1) A plant schematic showing the origin of all flows which are recycled (including, but not limited to, spent filterbackwash water, thickener supernatant, and liquids from dewatering processes), the hydraulic conveyanceused to transport them, and the location where they are re-introduced back into the treatment plant.

(2) Typical recycle flow in gallons per minute (gpm), the highest observed plant flow experienced in the previousyear (gpm), design flow for the treatment plant (gpm), and State-approved operating capacity for the plant where
the State has made such determinations.

(c) Treatment technique requirement. Any system that recycles spent filterbackwash water, thickener supernatant, or liquids from dewatering processes must return these flows through the processes of a system’s existing conventional or direct filtrationsystem as defined in §141.2 or at an alternate location approved by the Stateby June 8, 2004. If capital improvements are required to modify the recycle location to meet this requirement,all capital improvements must be completed no later than June 8, 2006.

(d) Recordkeeping. The system must collect and retain on file recycle flow information specified in paragraphs(d)(1) through (6) of this section for review and evaluation by the State beginning June 8, 2004.

(1) Copy of the recycle notification
and information submitted to theState under paragraph (b) of this section.

(2) List of all recycle flows and thefrequency with which they are returned.

(3) Average and maximum backwash flow rate through the filters and the average and maximum duration of the filter backwash process in minutes.

(4) Typical filter run length and a written summary of how filter run length is determined.

(5) The type of treatment provided for the recycle flow.

(6) Data on the physical dimensions of the equalization and/or treatment units, typical and maximum hydraulicloading rates, type of treatment chemicals used and average dose and frequency of use, and frequency at which solids are removed, if applicable.

[66 FR 31103, June 8, 2001]



### Subpart I—Control of Lead and Copper

S OURCE : 56 FR 26548, June 7, 1991, unless
otherwise noted.

§ 141.80 General requirements.

(a) Applicability and effective dates. (1)The requirements of this subpart I constitute the national primary drinking water regulations for lead and copper. Unless otherwise indicated, each of the provisions of this subpart applies tocommunity water systems and nontransient, non-community water systems (hereinafter referred to as ‘‘water systems’’ or ‘‘systems’’).

(2) [Reserved]


### 485 Environmental Protection Agency § 141.80

(b) Scope. These regulations establisha treatment technique that includes requirements for corrosion control treatment, source water treatment, lead service line replacement, and public education. These requirements are triggered, in some cases, by lead andcopper action levels measured in samples collected at consumers’ taps.

(c) Lead and copper action levels. (1)
The lead action level is exceeded if the
concentration of lead in more than 10 percent of tap water samples collectedduring any monitoring period conducted in accordance with §141.86 is greater than 0.015 mg/L ( i.e. , if the ‘‘90th percentile’’ lead level is greater than 0.015 mg/L).

(2) The copper action level is exceeded if the concentration of copper inmore than 10 percent of tap water samples collected during any monitoring period conducted in accordance with §141.86 is greater than 1.3 mg/L ( i.e. , if the ‘‘90th percentile’’ copper level is greater than 1.3 mg/L).

(3) The 90th percentile lead and copper levels shall be computed as follows:

(i) The results of all lead or coppersamples taken during a monitoring period shall be placed in ascending orderfrom the sample with the lowest concentration to the sample with the highest concentration. Each sampling result shall be assigned a number, ascending by single integers beginning with the number 1 for the sample with
the lowest contaminant level. The number assigned to the sample with the highest contaminant level shall be equal to the total number of samples
taken.

(ii) The number of samples taken during the monitoring period shall be multiplied by 0.9.

(iii) The contaminant concentration in the numbered sample yielded by the calculation in paragraph (c)(3)(ii) is the 90th percentile contaminant level.

(iv) For water systems serving fewer than 100 people that collect 5 samplesper monitoring period, the 90th percentile is computed by taking the average of the highest and second highest
concentrations.

(v) For a public water system thathas been allowed by the State to collect fewer than five samples in accordance with §141.86(c), the sample result with the highest concentration is considered the 90th percentile value.

(d) Corrosion control treatment requirements. (1) All water systems shall install and operate optimal corrosion control treatment as defined in §141.2.

(2) Any water system that complies with the applicable corrosion control treatment requirements specified by the State under §§141.81 and 141.82 shall be deemed in compliance with the treatment requirement contained in paragraph (d)(1) of this section.

(e) Source water treatment requirements. Any system exceeding the lead or copper action level shall implement all applicable source water treatment requirements specified by the State under §141.83.

(f) Lead service line replacement requirements. Any system exceeding the lead action level after implementation of applicable corrosion control and source water treatment requirementsshall complete the lead service line replacement requirements contained in §141.84.

(g) Public education requirements. Pursuant to §141.85, all water systems must provide a consumer notice of leadtap water monitoring results to persons served at the sites (taps) that are tested. Any system exceeding the lead action level shall implement the public education requirements.

(h) Monitoring and analytical requirements. Tap water monitoring for leadand copper, monitoring for water quality parameters, source water monitoring for lead and copper, and analyses of the monitoring results underthis subpart shall be completed in compliance with §§141.86, 141.87, 141.88, and
141.89.

(i) Reporting requirements. Systemsshall report to the State any information required by the treatment provisions of this subpart and §141.90.

(j) Recordkeeping requirements. Systems shall maintain records in accordance with §141.91.

(k) Violation of national primary drinking water regulations. Failure to comply with the applicable requirements of §§141.80–141.91, including requirements established by the State pursuant tothese provisions, shall constitute a violation of the national primary drinking


### 486 40 CFR Ch. I (7–1–12 Edition) § 141.81

water regulations for lead and/or copper.

[56 FR 26548, June 7, 1991; 57 FR 28788, June 29, 1992, as amended at 72 FR 57814, Oct. 10, 2007]

§ 141.81 Applicability of corrosion control treatment steps to small, medium-size and large water systems.

(a) Systems shall complete the applicable corrosion control treatment requirements described in §141.82 by the
deadlines established in this section.

(1) A large system (serving >50,000 persons) shall complete the corrosion control treatment steps specified in paragraph (d) of this section, unless it is deemed to have optimized corrosion control under paragraph (b)(2) or (b)(3)
of this section.

(2) A small system (serving ≤3300 persons) and a medium-size system (serving >3,300 and ≤50,000 persons) shallcomplete the corrosion control treatment steps specified in paragraph (e) of this section, unless it is deemed to have optimized corrosion control under paragraph (b)(1), (b)(2), or (b)(3) of this
section.

(b) A system is deemed to have optimized corrosion control and is not required to complete the applicable corrosion control treatment steps identified in this section if the system satisfies one of the criteria specified in paragraphs (b)(1) through (b)(3) of this section. Any such system deemed to have optimized corrosion control underthis paragraph, and which has treatment in place, shall continue to operate and maintain optimal corrosioncontrol treatment and meet any requirements that the State determinesappropriate to ensure optimal corrosion control treatment is maintained.

(1) A small or medium-size water system is deemed to have optimized corrosion control if the system meets the lead and copper action levels during
each of two consecutive six-monthmonitoring periods conducted in accordance with §141.86.

(2) Any water system may be deemedby the State to have optimized corrosion control treatment if the system
demonstrates to the satisfaction of the
State that it has conducted activities equivalent to the corrosion control steps applicable to such system under this section. If the State makes thisdetermination, it shall provide the system with written notice explaining the basis for its decision and shall specify the water quality control parameters representing optimal corrosion control in accordance with §141.82(f). Watersystems deemed to have optimized corrosion control under this paragraph shall operate in compliance with the State-designated optimal water quality control parameters in accordance with §141.82(g) and continue to conduct leadand copper tap and water quality parameter sampling in accordance with §141.86(d)(3) and §141.87(d), respectively. A system shall provide the State with the following information in order to support a determination under this paragraph:

(i) The results of all test samples collected for each of the water quality parameters in §141.82(c)(3).

(ii) A report explaining the test methods used by the water system to
evaluate the corrosion control treatments listed in §141.82(c)(1), the results of all tests conducted, and the basis forthe system’s selection of optimal corrosion control treatment;

(iii) A report explaining how corrosion control has been installed and howit is being maintained to insure minimal lead and copper concentrations at consumers’ taps; and

(iv) The results of tap water samples collected in accordance with §141.86 at least once every six months for one year after corrosion control has been
installed.

(3) Any water system is deemed to have optimized corrosion control if itsubmits results of tap water monitoring conducted in accordance with §141.86 and source water monitoring conducted in accordance with §141.88
that demonstrates for two consecutive 6-month monitoring periods that the difference between the 90th percentile tap water lead level computed under §141.80(c)(3), and the highest source
water lead concentration is less than the Practical Quantitation Level for lead specified in §141.89(a)(1)(ii).

(i) Those systems whose highest
source water lead level is below the Method Detection Limit may also be deemed to have optimized corrosion control under this paragraph if the 90th