The language related to identifying constraints is existing language from the rule and was not new in the proposal. The rationale for using data and documentation from previous studies performed by the system or from a system with comparable water quality characteristics is transferability. In those instances, the constraints were identified based on water that is the same or very similar in water quality characteristics. Other sources of information may identify constraints that don't apply to the system's water quality characteristics. Some constraints might not be actual constraints and can be overcome with additional treatment for simultaneous compliance with the LCRR and other regulations. For example, a system should consider organic precursor removal to reduce disinfection by-products which could allow elevated pH adjustment options, if the system has limitations on  orthophosphate discharge to wastewater.
Alkalinity is a required measurement parameter in the corrosion control treatment studies and would be a critical control parameter for systems using pH and alkalinity adjustment as their corrosion control treatment process.
EPA chose to not impose requirements in the rule to  dictate who is doing the studies or to require outside reviews of the results because  they would delay implementation of the optimal corrosion control treatment. Similarly, public review would delay implementation and is unlikely to provide much input as the results from the pipe loop and coupon studies are complex and require a good degree of technical knowledge. Even mandating third-party review with some degree of expertise may not add substantially to the review of the study results and would delay implementation of the optimized or re-optimized corrosion control treatment.
The final rule requires small and non-transient, non-community water systems with existing corrosion control treatment to maintain it until the State determines it is no longer necessary if they select a compliance option other than corrosion control treatment under § 141.93.
Agency guidance on the implementation of the CCT step requirements was also requested by commenters. See response to comment section 4.1.1 for further discussion of implementation guidance.
Requirement to Evaluate Orthophosphate Addition at Residual Concentrations of 1 and 3 mg/L
Summary of Comments
Two commenters expressed their general support for the inclusion of 1- and 3-mg/L orthophosphate residual evaluations as proposed for CCT studies in § 141.82(c). However, one recommended requiring systems to "sustain a minimum PO4 residual concentration in the distribution system of 1 mg/L." The other believed "greater definition on the minimum study requirements (e.g. water quality parameters, test duration, etc.) and an explanation of how to demonstrate what is a compliant testing device (e.g. pipe rig/loop tests with harvested vs. new lead pipe material) is necessary." A third commenter supported EPA's proposal that "water systems conducting corrosion control studies would not be able to rule out orthophosphate simply based on the increase in loading to wastewater treatment facilities." While this commenter agreed "phosphorous loading at wastewater treatment plants should not be used to eliminate consideration of orthophosphate for CCT," they suggested "discharge limits for wastewater should nonetheless be included in overall assessment of an optimal CCT design."
Commenters generally did not support including the evaluations of orthophosphate addition at 1 and 3 mg/L as proposed in § 141.82(c) and many disagreed with EPA's proposal that "water systems conducting corrosion control studies would not be able to rule out orthophosphate simply based on the increase in loading to wastewater treatment facilities." One commenter stated "[o]rthophosphate addition is not a one-size-fits-all treatment solution" and claimed the effective pH range for orthophosphate "likely precludes most of the Midwest where source waters are high in hardness, water softening is required, and pH/alkalinity adjustment is likely to result in optimized corrosion control." For such communities, the commenter stated that "evaluation or implementation of orthophosphate would not be an effective use of time and resources." Commenters also were concerned the proposed approach may result in broader adoption of orthophosphate-based inhibitors, claiming "[t]he net effect of EPA's definition of a corrosion control study effectively limits corrosion control treatment solutions to one option, high-dose orthophosphate addition;" that "the final rule must allow consideration of the full range of orthophosphate concentrations;" and that "[t]he final rule must recognize wastewater treatment impacts as a serious factor in decision-making." Another commenter was similarly concerned that "in the absence of clear guidance from EPA, regulators may push water systems to change their CCT to orthophosphate, which may not be optimum and may have unintended consequences." A third commenter was concerned with how the potential for broader orthophosphate adoption could adversely impact consecutive systems. The commenter claimed that "the proposed rule does not address the problem of consecutive systems" and that "[i]f one retail PWS exceeds a regulatory threshold but others do not, there is little reason for the PWS supplying the water to convert their entire system to zinc orthophosphate. This makes for a very complex situation." Other commenters expressed support for "a regional approach to the identification of optimal corrosion control treatment that allows for creative solutions while avoiding the use of the chemical orthophosphate" and suggested EPA "consider regional differences when recommending adding orthophosphate for CCT." One commenter indicated that "[f]or systems blending different water sources in the distribution system with different corrosion control treatment techniques applied to each source, maintaining a consistent orthophosphate concentration of 1.0 mg/L as P04 throughout the distribution system is not achievable." Another commenter characterized a 3-mg/L orthophosphate residual concentration as being "problematic and extremely difficult to obtain" and suggested instead that "[t]he required residual should be based on the specifics of each water system and part of their individual corrosion control treatment plan." A second commenter expressed a separate concern with a 3-mg/L residual, stating that it "potentially puts some PWSs into an undesirable position of being a contributor to Harmful Algal Bloom formation." The commenter recommended "letting the science dictate the appropriate orthophosphate levels needed for OCCT and having that level take into account local constraints as appropriate." A final commenter suggested adding greater specificity to the evaluation of pH/alkalinity-based options to prevent "inappropriately prioritize[ing] the selection of corrosion control treatment towards phosphate based options," "when a properly designed pH/alkalinity method may have been equivalent or superior," and to "ensure all [treatment] options are evaluated with an appropriate degree of rigor and that a fair comparison can be made."
Commenters also urged EPA to consider public health impacts as well as economic and environmental impacts to wastewater treatment plants, receiving water bodies and downstream drinking water sources. Other commenters noted the potential for negative consequences to distribution system pipe scales or coatings, one of whom suggested adding a scale analysis to determine "the presence of amorphous oxides and hydroxides" as these "would be a strong indicator that orthophosphate use may not be appropriate." The commenter also suggested allowing "water systems to select orthophosphate for corrosion control studies applying the minimum dose necessary to effectively reduce lead levels." One commenter claimed other drawbacks to the use of orthophosphate that could impact public health, stating that "[i]f a system has a disruption in their chemical feed system and they do not catch it, they will be solubilizing lead into consumers taps unknowingly. Another drawback to orthophosphate is the difficulty and concern that utilities will stop feeding orthophosphate once lead service line are removed, which could result in elevated releases of lead from premise plumbing." One commenter suggested EPA include "technologies that may be available now or developed in the future for corrosion control treatment by adding a statement that other treatment options may be approved by the state primacy agency or EPA." Another requested "EPA provide relief to POTWs receiving drinking water where orthophosphate is used as a CCT in order to offset the impacts of removing excess phosphorous."
Commenters also indicated general concerns with the potential for unintended impacts to drinking water systems (e.g., increased operating costs, long-term stability of market supply or affordability challenges due to surges in orthophosphate demand/pricing); the extent to which downstream orthophosphate removal could also lead to unintended impacts and burdens to wastewater treatment plants, particularly those in arid or semi-arid areas; and the extent to which orthophosphate would be less beneficial to systems whose elevated lead levels are primarily attributed to brass corrosion.
One commenter claimed, "EPA's analysis [of phosphorus loading to surface waters] underestimates the scope of the problem" and "failed to consider regional or watershed impacts." The commenter suggested EPA expand "its analysis to examine more closely the impacts... on water quality in different regions of the country" and "consider not just the potential cost of phosphorus removal for wastewater utilities, but also the potential loss of revenue for recreation, fisheries, and tourism industries from HABs." Another commenter believed the "proposed rule does not address the importance of scale analysis," which could serve as an "indicator that orthophosphate use may not be appropriate."
Commenters suggested revising the rule to provide systems and primacy agencies greater, site-specific flexibility in the selection of corrosion control treatment and consideration of downstream impacts to public health and the environment, noting a need for "flexibility to determine which CCT options are feasible in [the water system's] area and include only those options in their CCT studies" and that "[n]ot having flexibility in determining the proper dose will limit [the system's] ability to adequately address differing conditions within the system." Commenters also suggested revising the rule to "make it explicit that CCT evaluations can and should examine the full range of possible environmental impacts and costs;" expanding water quality parameters to receiving wastewater streams; enabling state regulatory agencies to consider downstream impacts; and providing clarification on the ability for water systems to use alternatives to orthophosphate-based inhibitors. In addition to phosphorus-related impacts, one commenter recommended EPA "take a holistic approach that focuses on simultaneous compliance [and] guards against unintended consequences within water systems." Another suggested allowing "more flexibility to revise standards and permits, promote wastewater reuse, or implement variances when orthophosphate is used." A third commenter suggested providing clean water utilities with regulatory flexibility, "such as considering the development of a variance or conducting a use attainability analysis (UAA) to account for increased phosphorus concentrations associated with the LCR." A fourth commenter suggested that the final rule "be clear that water systems must analyze straight orthophosphate at doses of 1 and 3 mg/L and not polyphosphate blends." Other commenters supported "a regional approach to address lead that will remove the majority of lead service lines in [the] community while avoiding the use of the chemical orthophosphate."
One commenter requested EPA clarify "when the provisions of § 141.82 can be applied to the primacy agency," stating that "[c]larification is needed to indicate if the primary agency shall be required to update WQP ranges... upon promulgation of the final rule, or if these minimum WQP standards are intended to be designated only during a corrosion control study in response to a Trigger Level or Action Level exceedance" and that "it is not clear if these minimum WQP standards would be required during these annual reviews."
Commenters noted the use of elevated orthophosphate residual concentrations may, for certain systems, have detrimental impacts on water quality and existing pipe scales in the distribution system (e.g., water discoloration, biofilm growth, cloudy water, or the formation of very small lead particulates). One commenter noted that, for these systems "making the decision to replace existing scales in order to successfully add orthophosphate is not a trivial decision. If that is the course pursued then the transition process would need to be carefully monitored." The commenter also identified small groundwater systems or systems with unlined iron pipes, where "[t]ransitioning from a sequestration strategy to a high-dose orthophosphate strategy will require also addressing iron and manganese treatment." Another recommended "removing the specified orthophosphate dose levels [1 and 3 mg/L] from the rule."
One commenter suggested "wastewater treatment facilities receive notification from the public water system prior to the system beginning the corrosion control study so wastewater treatment facilities can have input on potential impacts which can then be considered as part of the corrosion control study design." The commenter also believed "owners and operators of wastewater treatment facilities should be notified [of increases in orthophosphate residual in drinking water] so that wastewater treatment adjustments... can be planned and funded."
Commenters requested EPA provide guidance on evaluating CCT environmental impacts and costs; "address the unintended consequences of contributing more nutrient pollution to water bodies;" "guide coordination between public water utilities and downstream wastewater treatment plants when an upstream utility re-optimizes its CCT and begins adding orthophosphate;" and "support research into innovative approaches to phosphorous management and continue to support advanced understanding of corrosion control practices."
Agency Response
The final rule requires monitoring of the key water quality parameter for orthophosphate-based inhibitors as orthophosphate measured as PO4 as the residual. Orthophosphate-based inhibitors can include blends of ortho- and polyphosphate or just inhibitors containing orthophosphate, but the residual measurement will only count the orthophosphate. The Science Advisory Board report (EPA-SAB-20-007) supported the requirement that the phosphate inhibitor be orthophosphate-based. The report noted that research by Hozalski et al. (2005) and others (e.g., Holm and Schock, 1991) has shown that polyphosphate, as a metal chelator, can result in much higher lead levels than when using orthophosphate alone. EPA has finalized the revision to note that the key parameter is orthophosphate measured as PO4 as the residual from orthophosphate-based inhibitors, which can include blends of ortho- and polyphosphate or just inhibitors containing orthophosphate.
The use of orthophosphate for corrosion control can increase the phosphorus loading to wastewater treatment facilities. However, water systems conducting corrosion control studies cannot rule out orthophosphate simply based on the increase in loading to wastewater treatment facilities. The definition of optimal corrosion control treatment means the corrosion control treatment that minimizes lead and copper concentrations at users' taps while ensuring that the system does not violate any national primary drinking water regulations. The definition of optimal corrosion control treatment means the corrosion control treatment that minimizes lead and copper concentrations at users' taps while ensuring that the system does not violate any national primary drinking water regulations. SDWA Section 1412(b)(7)(A) requires that a treatment technique prevent known or anticipated adverse effects on the health of persons to the extent feasible. EPA has determined that orthophosphate treatment is a feasible corrosion control treatment technology in accordance with SDWA Section 1412(b)(4)(E). Therefore, eliminating orthophosphate as an option because of concerns unrelated to compliance with national primary drinking water regulations may prevent a system from installing the treatment technique that reduces to the extent feasible the risks of adverse health effects from lead in drinking water. In designing the CCT studies, water systems should evaluate the orthophosphate treatment options in the coupon screening and/or pipe loop/rig studies. EPA has examined the potential costs of additional phosphorus usage on wastewater treatment systems and has included this in the Economic Analysis for the final rule. Many commenters objected to the required evaluations of orthophosphate addition at 1 and 3 mg/L. Some commenters characterized these as high orthophosphate doses. EPA disagrees that these orthophosphate doses are too high to be considered in the corrosion control study. The commenters may have assumed that the dose was measured as P which would be three times greater than the dose measured as PO4. EPA is clarifying that the orthophosphate doses to be studied are measured as PO4. The high-end dose in the corrosion control study of 3 mg/L as PO4 is at the low end of the typical range used in the United Kingdom where 95% of public water supplies are dosed with orthophosphate (Hayes and Hydes, 2010), and in a manner that has not resulted in detrimental impacts (e.g., water discoloration, biofilm growth) commenters raised as a broad concern. EPA also notes that the 2018 edition of Recommended Standards for Water Works published by the Great Lakes  -  Upper Mississippi Board of State and Provincial Public Health and Environmental Managers, commonly referred to as the 10 States Standards, has a requirement that the total phosphate applied shall not exceed 10 mg/L as PO4 when sequestering iron and manganese, which are aesthetic concerns and not a health concern. There are also standards in the document for orthophosphate and blended phosphates for corrosion control. Under the design of phosphate system in Section 4.9.5c, the second note states that the system shall have a chemical feed system capable of maintaining an orthophosphate residual of at least 1.0 mg/L as P (3.0 mg/L as PO4) throughout the distribution system. The member States for this document are Illinois, Indiana, Iowa, Michigan, Minnesota, Missouri, New York, Ohio, Pennsylvania, and Wisconsin.
There are several comments about the benchmarks for orthophosphate included in the treatment studies and that pH/alkalinity options can be superior. That is why the study should evaluate all the options and the system should recommend pH/alkalinity adjustment if that is the superior treatment in the study. In the situation where the wholesaler does not want to adjust its treatment, then the affected purchasing system will need to implement the treatment change. EPA disagrees with the comment that the effective pH range for orthophosphate would preclude its use throughout much of the mid-West. While the pH range where orthophosphate works best is between 7.2 and 7.8, it can be effective at higher pH options. If the study shows that pH/alkalinity is more effective than orthophosphate for systems with high natural pH, then the system should recommend it.
As noted in section 4.5.1 of the response to comment document, EPA has created `bins' for the corrosion control studies. Scale analysis can be a useful tool in conjunction with the harvested pipe loop study. Systems with lead service lines that exceed the action level are required to do a harvested pipe loop study where the impact of orthophosphate on the existing scale can be directly assessed and the treatment performance compared against other options. See the main response in section 4.5.1 for more details on the corrosion control treatment studies.
With regard to systems turning off corrosion control treatment, Section 141.82(g) requires systems that have optimal corrosion control treatment to continue to operate and maintain it. Even for the small system compliance flexibility option where a system selects lead service line replacement or other options besides corrosion control, the system must continue to operate and maintain its existing corrosion control treatment until the State determines that it is no longer necessary.
Also, see response on the proposed corrosion control study requirements (section 4.5.1).
Proposed Requirements Related to Pipe Rig/Loop Testing and Coupon Studies
Summary of Comments
EPA received several comments relating to the pipe rig/loop-related requirements proposed in § § 141.82(c)(1)(ii), (c)(2)(ii), and (c)(3)(ii), under which systems may opt to use a pipe rig/loop when evaluating each of the corrosion control treatments prescribed in the proposed rule. EPA also received comments related to the proposal to clarify that "metal coupon tests can only be used as a screen to reduce the number of options that are evaluated using pipe rig/loops. Metal coupon tests would no longer be able to be used as the basis for determining the optimal corrosion control treatment."
Overall, two commenters generally supported the use of pipe loop/rig tests for CCT optimization studies. One of the commenters additionally suggested "the use of real-time, high frequency of monitoring" of the "produced water (at the water treatment plant) and its corrosive impact on range of lead coupons/pipe loops/solders/brass fittings." A third commenter also supported the approach, but only for "medium to large systems," noting that "pipe rig/loop studies may help systems identify not only OCCT, but potential harmful impacts related to corrosion control treatment changes."
Several commenters, however, interpreted the proposed provisions to exclusively require pipe rig/loop testing and raised concerns over eliminating other types of studies. One commenter stated that "[w]ater systems will not be able to implement the proposed rule's requirements without insights from other analyses being given comparable weight in decision-making" and that "[p]ipe loop studies can also have misleading results when completed absent other tools." Commenters also believed the exclusive use of pipe rig/loop tests would not allow for system-specific considerations;" would not be practicable, feasible, or implementable; would result in a significant burden to systems; would require significant technical support for systems to implement; may delay system efforts to implement treatment modifications that would reduce lead levels; and that many systems, particularly small or medium systems, would not be likely to have the technical, managerial, and financial capacity to conduct them. Another commenter raised concerns over the potential for lead service line harvesting activities, which are needed for pipe rig/loop studies, to pose a "risk to the customer as the disturbance could cause high lead in that home." Commenters suggested incorporating into the final rule additional state flexibilities for determining what corrosion control treatment evaluation and selection methods would be most suitable for the system, and to "account for variability in system size and available resources." Other commenters suggested "historical water quality data be an allowable alternative" to pipe rig/loop studies and revising the rule to limit pipe rig/loop testing to systems with lead service lines. Another commenter requested "reserving pilot-scale testing requirements for large systems, systems with [lead service lines], and studies performed in response to an Action Level exceedance."
Commenters also noted pipe loops/rig studies may yield results that are not representative of distribution system conditions and thus may not accurately inform treatment selection. One commenter acknowledged that pipe rig/loop studies "can be an important part of an overall assessment of corrosion control treatment," but cautioned that their results "are highly influenced by a multitude of factors;" that "several pipe loop studies in succession may be required;" and that "pipe loop experiments performed in a relatively short period of time is problematic and will, in many cases, lead to erroneous conclusions if they are rushed and the selection of a corrosion control practice is based on these results. Another commenter also asserted that pipe loop study "test results... often have a high degree of variability" that would render limitations with the approach and make it "difficult to extrapolate [study results] to full-scale application." Instead, the commenter suggested "the final rule and preamble should acknowledge the limitations of relying on a single evaluation technique and promote the use of a robust weight-of-evidence approach to making corrosion control treatment decisions." To support their position, the commenter provided "flow through harvested pipe data from several water systems," to "illustrate the challenges of interpreting highly variable data where the mean lead concentrations observed [in pipe loop studies] are well over concentrations that will be acceptable at full-scale implementation."
EPA proposed to clarify that "metal coupon tests can only be used as a screen to reduce the number of options that are evaluated using pipe rig/loops; that metal coupon tests would no longer be able to be used as the basis for determining the optimal corrosion control treatment." Four commenters expressed general support for such an approach.
Several commenters did not support the inability to use coupon studies as a basis for determining the optimal corrosion control treatment and many requested allowing it in the final rule. One commenter asserted that "[c]oupon studies are an essential tool for corrosion control studies" that are "needed to support cost effective, timely, and sound corrosion control treatment decisions." The commenter suggested "the final rule and preamble should not discount the use of coupon studies in making corrosion control decisions." A second commenter provided anecdotal information supporting their position that "[c]oupon studies and pipe loop studies typically obtain the same results unless the lead pipe scale changes" and that ""copper corrosion control can be predicted by coupon studies." According to the commenter, results from a coupon study yielded "nearly the same removal percentages" and "predicted similar removal percentages for the corrosion control treatments" as a pipe rig/loop study that was conducted by the same water system. The commenter additionally stated that they "would prefer some coupon data to inform the decision rather than no empirical data at all, which could be a result of the proposed rule language." The commenter believed that "small and medium systems selecting a treatment option based on experimental data is better than implementing multiple system-wide corrosion treatments to attempt to find the optimal treatment" and claimed that "[m]ost systems will make treatment recommendations with very little data and follow EPA OCCT guidance without a pipe loop study." A third commenter stated a coupon testing protocol has been developed that "has been proven to be as representative as pipe loop testing in side-by-side comparisons."
One commenter suggested allowing the use of corrosion coupons when used within in-line (i.e., closed loop) systems.
One commenter requested clarification on the terms "pipe rig/loop test" and "metal coupon test," noting there to be a lack of generally accepted industry terminology surrounding these.
Finally, commenters requested EPA provide guidance on "acceptable protocols for and the length of [pipe rig/loop] studies" and that "to successfully implement the revised LCR, additional technical and financial resources must be made available to smaller systems to adequately implement pipe rig/loop studies under the revised rule." Commenters also requested EPA guidance on the use of coupon tests as a screening method in accordance with the provisions in § 141.82(c).
Agency Response
In Section 4.5.1, EPA provided a bin structure to describe the appropriate type of study by system size, lead concentration, presence of lead service lines and existing CCT treatment. EPA disagrees with the broad assertion that pipe loops do not yield representative results. A properly designed pipe loop allows systems to closely simulate actual distribution system and premise plumbing conditions. It also allows systems to conduct a direct comparison of corrosion control options, offering a more robust basis for decision-making on the specific conditions that would reflect optimized corrosion control treatment. Commenters also noted that some small systems may not have the technical capacity to construct and operate a harvested pipe loop study. EPA notes that in these cases the final rule provides flexibility to these small systems to implement a lead service line replacement or point-of-use program. See response in section 4.5.1 for clarification on which systems need to use pipe loops and when coupon studies can be used.
Commenters indicated that, for some systems, coupon studies rather than pipe loop/rig studies may be an appropriate treatment recommendation tool. EPA agrees that coupon studies can be used for systems that do not have lead service lines. The final rule includes requirements to allow coupon studies to be the basis for treatment recommendation for systems that do not have a lead action level exceedance and lead service lines. For systems with lead service lines, EPA believes that the corrosion control treatment changes needed for systems above the action level merit more thorough investigation. EPA has retained the requirement that coupon studies can only be used as a screening tool for these systems because of the Agency's concern that metal coupons, in these cases, would not be representative of existing scale conditions in lead service lines or leaded plumbing materials. For these systems, coupon studies can serve as a screen to reduce the number of options for the harvested pipe loop study, but they may not to be used as the basis for determining the optimal treatment.
EPA acknowledges "pipe rig/loop test" and "metal coupon test" are terms that do not have a universally accepted definition in the drinking water industry, there are widely understood meanings based on the years of experience water systems have had with the current LCR that uses these terms. The Agency believes it would be best to address this consideration through implementation guidance, rather than developing formal regulatory definitions. The development of regulatory definitions may be too prescriptive and may prevent states from making individual determinations as to the type and nature of pipe loop/rig or coupon test that would best address state concerns and system-specific conditions. EPA also notes there is existing Agency implementation guidance that offers additional information describing the nature of pipe loop/rig and metal coupon tests. EPA will work to develop or update guidance on the matter as industry practices or terminology evolve over time. See related discussion on implementation guidance in the section 4.1.1 response.
4.6 State Designation of OWQPs (Initial Optimization & Re-Optimization)
Summary of Comments
EPA received several comments on both the procedures proposed in § 141.82(d) for state designation of optimal corrosion control treatment and re-optimized corrosion control treatment and the procedures proposed in § 141.82(f) for states to designate optimal water quality parameters (OWQPs) after "reviewing the results of tap water and water quality parameter monitoring by the water system, both before and after the water system installs optimal corrosion control treatment."
One commenter suggested adding a paragraph to § 141.82(d) that would specifically describe "designation of initial OCCT for large systems." Two commenters indicated that large systems installing, rather than re-optimizing, corrosion control treatment did not appear to be addressed in § 141.82(d) and suggested adding a paragraph specifically describing designation of initial optimal corrosion control treatment for these systems. Another commenter was concerned with proposed § 141.82(d)(3), under which a state may designate alternative corrosion control treatment(s) from what has been recommended by the water system. The commenter was concerned that the provision may be implemented in such a manner that "may allow the State agency to redefine [the water system's] optimized status and dictate increased ortho-phosphate dosages, regardless of study findings."
Under the proposal, states would be required to designate values for the specific OWQPs prescribed in § 141.82(f)  -  namely pH, corrosion inhibitor concentration (if a corrosion inhibitor is used), and alkalinity (if alkalinity is adjusted as part of the system's optimal corrosion control treatment). In addition, states may "designate values for additional water quality control parameters determined by the State to reflect optimal corrosion control for the water system." One commenter provided a general suggestion for EPA to "tighten acceptable WQP limits, including allowing online continuous instrumentation." The commenter stated that "[v]ariability in chemistry can significantly affect corrosion and release from lead sources" and that continuous monitoring is "necessary to optimize corrosion control" and "particularly important to ensure that treatment dosages and water chemistry remain stable within the distribution system."
With regard to the prescribed manner in which states would designate OWQPs under proposed § 141.82(f)  -  at each entry point to the distribution system and in all tap samples  -  some commenters suggested EPA consider including provisions that also would allow states to set WQPs for certain zones within the distribution system. One commenter noted circumstances where, "[f]or systems blending different water sources in the distribution system with different corrosion control treatment techniques applied to each source, maintaining a consistent orthophosphate concentration of 1.0 mg/L as PO4 throughout the distribution system is not achievable." In light of such circumstances, the commenter requested that "EPA include provisions to allow representative WQP sample sites of each zone with different WQP targets to be identified." Another commenter raised a separate consideration for which they supported such an approach. The commenter stated their concern that water corrosivity "in different geographical areas can vary significantly" and asserted that "[i]f the challenge of water quality zones is left unaddressed, assessments of lead release in any given system can be erroneous." As such, the commenter recommended revising the rule to ensure that "water quality parameters and corrosion control treatment are properly adjusted to address actual worst-case conditions." Finally, the commenter requested that, "[s]hould EPA decide against addressing this problem, it must provide its rationale and the peer-reviewed science that supports it."
Commenters also provided suggestions on specific provisions within proposed § 141.82(f). With regard to the proposed requirement in §§ 141.82 (f)(1)(ii) and (2)(ii)  -  for systems optimizing or re-optimizing CCT,  the state would be required to designate an OWQP using for a minimum pH value "equal to or greater than 7.0, unless the State determines that meeting a pH level of 7.0 is not technologically feasible or not necessary for the system to achieve OOCT"  -  one commenter indicated that they did not interpret the provision as a requirement for a minimum pH and thus suggested removing the "unless the State determines" clause. Another noted that systems "adjust[ing] pH to meet or exceed 9.2... creates a potential to exceed the Secondary Treatment for effluent requirement at 40 CFR 133.102(c) (i.e. pH values be maintained between 6.0 and 9.0)." A third raised a similar point and suggested EPA include guidance language "pertaining to the secondary MCLs and why pH values outside this range might be appropriate." A final commenter expressed their support of proposed § 141.82(f)(1)(iv), where, for all tap samples, the state would designate a minimum orthophosphate concentration "equal to or greater than 0.5 mg/L as orthophosphate, unless the State determines that meeting an orthophosphate residual of 0.5 mg/L is not technologically feasible or is not necessary for the system to optimize corrosion control."
One commenter supported the proposed requirement in § 141.82(f)(1)(iv), applicable to systems installing optimized corrosion control treatment with an orthophosphate-based corrosion inhibitor, to maintain an orthophosphate concentration "equal to or greater than 0.5 mg/L" in all tap samples. For a similar provision in § 141.82(f)(2)(iv), which would apply to systems re-optimizing corrosion control treatment with an orthophosphate-based corrosion inhibitor, the commenter suggested removing the proposed requirement for an orthophosphate concentration "equal to or greater than 1.0 mg/L" in all tap samples.
EPA also received some comments that were specific to the proposal to "remove calcium carbonate stabilization as a potential CCT technique and thus calcium as a regulated WQP." One commenter expressed their support for the removal of calcium as a regulated WQP but requested that "EPA make a clarification to continue to allow the use of [calcium-based] lime for pH and alkalinity adjustment." Another commenter supported elimination of the CCT technique but did not support the subsequent removal of calcium as a regulated WQP, claiming that "[c]alcium is also an important water quality parameter because it affects the level to which pH and alkalinity treatments can be implemented without scaling, and calcium can bind orthophosphate at higher pHs." Other commenters similarly supported maintaining calcium as a regulated WQP (see discussion further below).
In addition, EPA received comment on additional parameters that could be included as regulated WQPs in the final rule. One commenter suggested that "water quality parameters need not be limited to direct measures of a specific corrosion control strategy but could include leading indicators" and identified "oxidation reduction potential, other metals such as iron, and hardness" as possible parameters for consideration. Two commenters were concerned that if "[water systems] focus only on pH, alkalinity and orthophosphate levels, they may be missing the cause or causes of increased lead solubility in their system" and suggested revising the proposed rule to provide consideration of other water quality parameters that may serve as indicators for potential lead solubility issues, such as disinfectant type and oxidation reduction. A fourth commenter suggested including water quality parameters listed in the EPA Optimal Corrosion Control Guidance Manual.
Other commenters provided more specific suggestions for additional WQPs to consider including in the final rule. One suggested including water temperature, conductivity, and calcium concentrations based on the commenter's position that "[w]ater temperature affects ALL chemical reactions and solubilities, including pH, alkalinity, calcium, orthophosphates, disinfectant residual decay, nitrification, etc." The commenter also suggested conductivity as "a general water chemistry parameter that accounts for the soluble anions and cations and is thereby applicable under all corrosion control treatment options." Another suggested including calcium and temperature as regulated water quality parameters in the final rule since they "can still provide important information about the nature and condition of protective lead scales in service lines." The commenter also urged "expanding[ing] the proposed water quality parameter list to all the factors known to significantly impact lead corrosion and lead release" and suggested including "chlorides, sulfates, manganese, iron, aluminum, and the formation/dissolution of protective scales in lead service line," based on the commenter's position that they are "known to have potentially significant impacts on lead corrosion and lead release" and "play a signiﬁcant role in inhibiting or exacerbating lead corrosion in diﬀerent distribution systems." The commenter also requested "a scientifically defensible justification" if "EPA leaves its proposed list unchanged."
In addition, several commenters requested EPA guidance, training and tools that would provide technical assistance to states in reviewing corrosion control study results and implementing subsequent rule requirements in proposed § § 141.82(d) and (f) (i.e., state designation of optimal corrosion control treatment and re-optimized corrosion control treatment, review of treatment installation, and specification of optimal water quality control parameters). A final commenter generally suggested that "States should be provided with adequate resources to review, capture, and improve water quality parameters with a short turn-around."
Agency Response
EPA has revised § 141.82 so that large systems without corrosion control treatment are covered under the optimization pathway and will have optimal corrosion control treatment. This will address medium systems that grow to be large systems, which meet the definition in the final rule of a system without corrosion control treatment. EPA has retained the requirement to allow States to either approve the system's recommended treatment or designate an alternative corrosion control treatment  and to notify the system in writing and explain the basis for its decision. States will need to document why they have selected an alternative and other than the larger systems, State personnel will likely be more knowledgeable about corrosion control treatment than the system's personnel.
While EPA did not propose changes to the frequency of water quality parameter monitoring, it agrees that continuous monitoring can be  an effective way of measuring some of the key water quality parameters such as pH to ensure better process control and avoid long excursions and violations. Setting the minimum or range for an optimal water quality parameter would involve more factors than monitoring frequency, such as seasonal water source variability, mixing zones within the distribution system, and water demand throughout the distribution system. The structure of the rule encourages more frequent monitoring with the excursion calculations discussed in § 141.82(g) that details how water quality parameter excursions are calculated when there are multiple samples on the same day, one sample per day, or on days when no samples are taken. Systems sampling less frequently than daily are more likely to have multiple day excursions because the daily value from the most recent day that a water quality parameter was measured at the sampling location will apply on days when no measurement was conducted. Systems with more than nine days of excursions in a six-month period are in violation of the treatment technique. Systems with expertise to use continuous monitoring are much less likely to have long excursions because treatment adjustments can be made during the day when the parameter goes outside its optimal range.
There is sufficient flexibility in the rule to address water variability in different zones. The cited example indicated concerns with a minimum orthophosphate residual of 1.0 mg/L, which is set by the State after review of follow-up monitoring following re-optimization. If the State determines that it is not technologically feasible or necessary for the system to meet this residual in a particular monitoring location, it can set a lower value for it. EPA is requiring that the water quality parameter sites in the distribution system be included in the site sampling plan along with the lead and copper tap sampling sites. In addition, the find-and-fix requirements can provide better zone coverage by requiring the addition of new water quality parameter locations if one is not located within the same pressure zone and on the same size water main within a half mile of the tap monitoring site with a lead action level exceedance. These sites will be added to the minimum number of sample sites for systems required to meet optimal water quality parameters. These sites can be added until the system has twice the minimum number of sites listed in Table 1 of § 141.87(a)(2). When a system exceeds this upper threshold for the number of sites, the state has discretion to switch out sites that have been added if the newer site can better assess the effectiveness of corrosion control treatment.
The minimum pH of 7.0 in the distribution system samples (in the absence of a state determination that it is not technologically feasible or necessary for the system to optimize CCT) was in the 1991 lead and copper rule. EPA is not changing the requirement for this minimum pH value because waters with a pH below 7.0 are corrosive towards lead and copper materials and a pH below 7.0 is below the optimal range for orthophosphate if it is being added. EPA will update the optimal corrosion control treatment guidance to emphasize that pH values above the upper bound of the secondary MCL range (> pH 8.5) would be appropriate.
EPA agrees with commenters that supported the proposed minimum orthophosphate residual concentration of 0.5 mg/L (as PO4) and has retained it in the final rule for systems installing orthophosphate. States can set a lower minimum when it is determined that it is not technologically feasible or necessary for optimal corrosion control. EPA disagrees with the comment about the minimum orthophosphate concentration of 1.0 mg/L as PO4 in all distribution system tap samples. Such systems that are triggered into re-optimization have an existing, orthophosphate-based corrosion control treatment and still exceeded the trigger or action level. EPA believes that a higher residual concentration is necessary to control lead and copper concentrations since the existing corrosion control treatment did not keep the systems below the trigger or action levels. However, EPA notes that the final rule provides states the flexibility to determine, on a case-by-case basis, that meeting an orthophosphate residual of 1.0 mg/L is not technologically feasible or is not necessary for a system to optimize corrosion control.
Optimal corrosion control treatment is defined as the corrosion control treatment that minimizes lead and copper at users' taps while ensuring that the treatment does not cause the system to violate any national primary drinking water regulations. The LCRR retains the pH/alkalinity adjustment and inhibitor addition approaches that must be evaluated by systems in assessing corrosion control treatments. While EPA removed the calcium carbonate stabilization approach as a mandatory approach that must be evaluated to identify optimal corrosion control treatment, systems and States may find that it is the optimal corrosion control treatment for some systems. For systems conducting optimization or re-optimization studies, alternatives other than pH/alkalinity adjustment or use of corrosion inhibitors can be compared against these corrosion control treatments in the study to demonstrate that the alternative is as effective or more effective than the listed corrosion control treatments to demonstrate that it is the optimal corrosion control treatment. In the final rule,  § 141.82(f)(1)(vi)  provides  that the State may designate values for additional water quality control parameters determined by the State to reflect optimal corrosion control for the water system. Thus, for systems where the state is retaining calcium carbonate precipitation as the optimal corrosion control treatment for the system, it can has designate calcium, conductivity and temperature as optimal water quality parameters along with pH and alkalinity for the system unless the system exceeds the lead trigger or action level. If the trigger or action level is exceeded, the system will need to demonstrate through the re-optimization process that adjustments to the calcium carbonate precipitation process is the optimal corrosion control treatment process for the system. Similarly, if a system can demonstrate that a lead oxide scale (PbO2) is the optimal corrosion control treatment and it is approved by the State, the State could designate oxidation-reduction potential or free chlorine as optimal water quality parameters along with pH. The key parameters would be identified from the corrosion control study and the range from the follow-up monitoring. There are also parameters that can impact the effectiveness of corrosion control treatments, such as iron and manganese. In systems where the levels could interfere with corrosion control treatment, States may want systems to monitor these parameters as optimal water quality parameters. Several of the parameters listed by commenters would be important in evaluating long-term treatment changes, such as chloride and sulfate, if a system is considering switching coagulants, but may not be key parameters in assessing the effectiveness of the corrosion control treatment. EPA believes that additional water quality parameters can best be identified through this system-state interaction.
Agency guidance on the implementation of the CCT step requirements was also requested by commenters. See response to comment section 4.1.1 for further discussion of implementation guidance.
4.7 Corrosion Control Treatment Options
EPA received comments on the corrosion control treatment (CCT) options listed in the proposed rule, including comments on the proposal to remove calcium carbonate stabilization as a CCT method. EPA also received comments on other CCT options that were not listed in the proposed rule.
Corrosion Control Treatment Options Listed in the Proposed Rule
Summary of Comments
EPA received one comment relating to the corrosion control treatment (CCT) options listed in the proposed rule. The commenter suggested EPA "consider removing silica-based inhibitor adjustment as a CCT method," based on the commenter's position of there being a "lack of research demonstrating its effectiveness in minimizing lead and copper levels."
Agency Response
EPA's review of available literature did not support removing silica-based inhibitors as a corrosion control treatment option. EPA notes that systems using silica-based inhibitors, upon finding they are no longer optimized because of trigger or action level exceedances, would be required to re-optimize their corrosion control treatment. That process would require a comparison of the system's existing usage of a silica-based inhibitor against other corrosion control treatment alternatives. Where alternative, non-silica-based treatments are found to reflect optimal corrosion control, the system would be required to install it in accordance with the rule's provisions for optimized treatment.
Proposed Removal of Calcium Carbonate Stabilization as a Corrosion Control Treatment Method
Summary of Comments
As indicated in the preamble to the proposed rule, EPA proposed to "eliminate the option of calcium carbonate stabilization as a CCT because literature indicates that calcium carbonate does not form a film on lead and copper pipes to a level that makes it effective as a CCT option." EPA received comments expressing support for the proposed elimination. One of the commenters also affirmed EPA's finding that calcium carbonate stabilization is less effective as a CCT option, stating that "[b]ased on [the commenter's] knowledge, there is little or no research that supports corrosion control effectiveness of calcium carbonate stabilization." Another expressed that they "[did] not object to the removal of calcium carbonate precipitation as a corrosion control treatment option."
An equivalent number of commenters were not supportive of the proposed removal. Most favored maintaining the CCT method for the sake of providing systems with a broader array of treatment options. A smaller subset of commenters did not agree with EPA's basis for the removal and claimed that "[c]alcium carbonate as a water chemistry method to control corrosion has been shown to be an effective CC technique" and that "buffered water treatment method needs to remain a cornerstone of CCT as it is often the most system effective and cost effective method available to many systems." Another final commenter claimed that "[s]everal large water systems in Missouri have successfully use [sic] calcium carbonate for their CCT for decades with no compliance issues in meeting the action level."
Many commenters noted the cascading impact of the proposal on systems currently using calcium carbonate stabilization as their designated optimal corrosion control treatment and sought clarity on how those systems would proceed under the revised rule. Commenters claimed the proposal "significantly modifies what constitutes optimized corrosion control" for these systems and recommended clarifying in the final rule that they would not be required to "change current corrosion control practice unless studies pertaining to a trigger or action level exceedance indicate a change is necessary." One commenter asserted that "[r]equiring these water systems to modify their CCT without any indication that they exceed either the Action Level or Trigger Level is unnecessary, cost-prohibitive, and unreasonably burdensome on these water systems" and suggested that "EPA should review the economic impacts of the elimination of calcium carbonate for these water systems." Another commenter stated that "[w]ithout guidance as to how a water system using calcium carbonate for corrosion control is to proceed, it could be argued that the water system is operating without an approved corrosion control technology as of the promulgation date of this rule." The majority of these commenters recommended revising the rule to allow these systems to continue operating the treatment so long as they do not exceed the trigger or action levels. Upon such an exceedance, these systems would then be triggered into evaluating other CCT methods and subsequently implementing the treatment transition. Alternatively, one of the commenters suggested EPA "provide further guidance as to what will be required of such water systems, which should at least include a reasonable sunset period that will allow enough time for sufficient studies to be concluded to ensure the safe transition to an approved corrosion control treatment option." A final commenter suggested that "EPA provide guidance and training for state regulatory agencies to prevent unnecessary and/or unwise changes to water systems' CCT" and state in such guidance that "stable systems (e.g., water systems that have been successfully and reliably operating the same way for many years in the absence of detections of elevated lead) should not be required to change their CCT."
One of the commenters indicated they had installed calcium carbonate stabilization as their state-designated optimal corrosion control treatment based on corrosion control studies they had previously completed in accordance with the Lead and Copper Rule. The commenter also noted that lead and copper samples were "non-detectable" at dedicated sampling stations and that "all triennial at-the-tap samples were below the actions levels" for nearly two decades. In light of the proposed revisions, the commenter sought clarity on how to proceed in complying with the revised rule, stating that "it is unclear, based on the proposed revisions, whether [the commenter] should continue monitoring the WQPs determined from the results of our corrosion control study, or a new corrosion control study needs to be conducted to meet the requirement of proposed LCR."
Agency Response
EPA agrees with commenters that calcium carbonate stabilization has not been shown to be an effective corrosion control treatment strategy. EPA believes the lack of support in the available literature for the use of calcium carbonate stabilization in reducing tap lead levels justifies removing it from the list of treatments required to be evaluated in a corrosion control study. The treatment options that will remain continue to offer a range of options for systems to provide OCCT.
With regard to comments and concerns regarding calcium carbonate stabilization processes currently in place, system will not be required to replace calcium carbonate treatment and that treatment may continue to operate provided the system continues to meet the lead trigger level.. Systems that have had water quality parameters designated will continue to comply with those parameters including monitoring and reporting requirements. A new corrosion control study will not be required for such systems that continue to operate calcium carbonate treatment and continue to not exceed the lead trigger level. If a water system using calcium carbonate stabilization exceeds the lead trigger level or the lead action level, it would no longer have the option to continue its use. See related discussion in section 4.6 regarding the final rule's inclusion of language that  allows these systems to maintain calcium carbonate stabilization as their optimal corrosion control treatment and gives the state the authority to set the appropriate water quality parameters associated with that treatment. If a system no longer had the option to continue the use of calcium carbonate stabilization then that system would proceed with a corrosion treatment study if required based on system size monitoring of water quality parameters before and after installation of corrosion control treatment based on the applicable schedule of the LCRR
Other Corrosion Control Treatment Options Not Listed in the Proposed Rule
Summary of Comments
EPA received comment on potential corrosion control treatment options beyond those listed in § 141.82(c) of the proposed rule (i.e., alkalinity and pH adjustment, addition of an orthophosphate-based corrosion inhibitor, or addition of a silicate-based corrosion inhibitor). Four commenters suggested a potential option for certain systems, those using chlorine for secondary disinfection, to develop or maintain insoluble, tetravalent lead scales as a corrosion control treatment method. The commenters also suggested that these systems could achieve or maintain the scales by adjusting pH and adding treatment for disinfection byproduct pre-cursor removal.
Another commenter suggested including "methods to minimize iron corrosion" and claimed that it "can impact particulate lead levels;" that "optimizing corrosion control involves managing both dissolved and particulate lead;" and that "[h]istorical guidance has focused on optimization of water chemistry to minimize dissolved lead levels."
One commenter suggested that "[o]ther corrosion control treatments should be made available if proven effective" and claimed that "[m]anganese sulfate, which has not been studied extensively, has been successful in some studies as a corrosion inhibitor."
A commenter suggested EPA develop, approve, and implement a "new system of tiered products" that water systems could utilize directly, and without need for prior corrosion control evaluations or studies. According to the commenter, the tiered products would consist of "[p]roducts/technologies that have a proven track record of putting systems into compliance 99% of the time."
Agency Response
With regard to comments suggesting potential options for corrosion control treatment, EPA agrees with comments suggesting that treatment strategies to meet other NPDWRs could complement OCCT in reducing tap levels and facilitate simultaneous compliance with the NPDWRs. . Under the LCRR, states are required to set optimal water quality parameter ranges or minimums and have the discretion to set additional optimal water quality parameters. Any corrosion control strategy would need to be evaluated, including the minimum required elements, in a corrosion control study that identifies the corrosion control treatment that minimizes lead and copper levels at consumers' taps.
EPA agrees that overall control of corrosion in water systems would have a positive impact on reducing lead levels at taps. The use of OCCT would contribute to that control. EPA also agrees that considering particulate lead levels and the presence of metal scales in corrosion control treatment is important in reducing lead exposure. EPA concludes that consistent distribution system operational practices and consistent use of corrosion control based on corrosion control treatment studies that evaluate all aspects of source water chemistry and corrosion control treatment strategies can reduce exposure from all forms of lead in the distribution system.
In response to the comment regarding other corrosion control being available, based on the information reviewed in developing the LCRR, EPA believes that the corrosion control treatment methods identified represent the most practical and effective means of minimizing tap lead levels. EPA does not have information regarding the applicability or efficacy of manganese sulfate in public water system in reducing tap levels for it to be considered a corrosion control treatment to satisfy the requirement for OCCT under the LCRR.
With regard to the comment suggested that EPA develop a tiered criteria for corrosion control treatment, implementation of the previous LCR including corrosion studies conducted and investigation into exceedances of the current lead AL in multiple systems clearly indicate that are a number of unique circumstances in individual water systems including source water quality, treatment methods and distribution system construction and operation that effect tap lead levels and LCR compliance. Therefore, EPA does not believe that any tiered criteria could fully account for all these variables and allow for a conclusion as to OCCT for a given water system..
4.8 Daily Optimal Water Quality Parameter Calculation Requirements
Summary of Comments
EPA received comments on the proposed requirement in § 141.82(g) for calculating the daily values for State-specified water quality parameters used to determine corrosion control treatment compliance. Some commenters recommended that EPA consider calculating separate daily values for each distribution system entry point rather than a single, system-wide daily value calculated using the procedures prescribed in § § 141.82(g)(1) and (2). The commenters believed requiring a single, system-wide daily value would cause systems with multiple sources to incur violations more frequently than those with a single source. One commenter recommended that daily values "should be based upon a sampling plan with guidance pertaining to when and where a system should sample," and that the "sampling plan should address multiple sources, including how seasonal source are used."
Agency Response
EPA disagrees with the recommendation to calculate daily values at each entry point to the distribution system. This approach would not ensure a consistent level of corrosion control treatment and minimized lead and copper levels for all consumers served by the distribution system. EPA notes that states have considerable flexibility in setting optimal water quality parameters and adjusting them as needed over time. Water quality tap sample monitoring must take into account different sources, treatment methods and seasonal variability. EPA agrees that a sampling plan would have considerable value in water quality parameter monitoring both in ensuring representative monitoring and consistent operation of corrosion control treatment.
4.9 CCT Study vs Re-Optimization
Summary of Comments
EPA requested comment on "potential actions water systems could take to adjust their corrosion control treatment and how they should work with the state to determine if adjustments to the treatment would better optimize corrosion control." The proposed steps by which a water system exceeding the lead trigger level or copper action level would be required to re-optimize their corrosion control treatment are prescribed in § 141.81(d). Additional requirements associated with these steps are further described throughout § 141.82.
EPA received several comments suggesting that the final rule incorporate a separate `trend analysis' or a `find-and-fix evaluation' where systems first would review how effectively they are implementing their existing CCT and identify potential modifications prior to considering, evaluating, or conducting CCT studies for an alternate OCCT that is not already installed. Commenters suggested this approach to address concerns over the proposed procedures in § 141.81(d) potentially triggering a `restart' of OCCT designation and subsequent installation of a new OCCT. One commenter suggested that "[e]valuation of existing treatment modification can be done using desk-top, coupon, analogous system, or partial system or full-scale trials." Another commenter suggested that "a desk-top evaluation be conducted by the system to determine optimal corrosion control treatment;" that the "need for, and requirements of, a pipe loop study be determined through discussions with the state primacy agency," and that "changes to corrosion control treatment be implemented on a reasonable timeframe following discussions with the state primacy agency." A third commenter suggested the final rule "[e]xplicitly encourage the routine collection and trend analysis of water quality parameters."
One commenter generally suggested that "[r]e-optimization should focus on making improvements to existing treatment when appropriate and require additional studies when that is insufficient." Another commenter suggested adding "flexibility in what constitutes `re-optimization.' Sometimes it is simply a treatment process issue that causes a system to exceed when they have CCT. Submitting plans on how to prevent these process issues from happening in the future should be adequate- a system shouldn't have to go through a study or re-evaluation of various treatment options to be considered "re-optimized.'"
In addition to conducting trend analyses/evaluations in responses to trigger or action level exceedances, some commenters suggested requiring systems to perform them when considering new sources or treatment changes, or to inform long-term CCT improvement measures. A final commenter also suggested including a trend analysis during sanitary survey reviews.
Agency Response
EPA agrees with commenters who suggested there should be more flexibility allowed in the re-optimization process  and that a `bin' approach can provide more flexibility and ease the cost and burden for some systems performing corrosion control studies. The bin approach is based on system size, presence of lead service lines and the 90[th] percentile tap lead levels. EPA  agrees it may be appropriate for systems that are between the trigger level and action level to install optimized treatment without the need for a corrosion control study unless deemed necessary by the State to ensure the system will achieve optimal levels of corrosion control in its distribution system. The bin approach requires pipe loop studies only for systems with lead service lines that exceed the lead action level. Desktop studies as recommended by commenters are an option under the bin approach. Also as recommended by commenters, systems can have treatment modifications approved by the state without the need for additional studies. See the rsponses to subsections 4.3 and 4.4 for a summary of how EPA has modified requirements for the optimization and re-optimization pathways, respectively, in the final rule. See also the response in section 4.5 detailing the `bin' approach for determining CCT study requirements based on a system's status of CCT, lead service lines, and 90th percentiles.
 EPA has not incorporated the suggested requirement for completing trend analyses in response to trigger or action level exceedances, new sources, treatment changes or CCT improvement or during sanitary survey reviews. EPA agrees with comments that such analyses may have considerable value for evaluating corrosion control treatment in certain circumstances. However, the Agency believes that the need for such analyses would be best determined by states on an individual system basis. (See additional discussion on sanitary surveys in section 4.10.)
4.10 CCT Review During Sanitary Surveys
Summary of Comments
Four commenters supported the requirement to review corrosion control treatment and water quality parameter data during sanitary surveys as proposed. Another commenter supported the proposal, but suggested "the review during a Sanitary Survey should go farther and evaluate WQPs relative to Pb corrosion for all systems."
Several commenters supported the periodic review of corrosion control treatment and water quality parameter data but did not believe the review should be completed as a part of the sanitary survey process; "believe[d] the States should be able to exempt Corrosion Control Surveys and associated treatment based off historical lead results and the information gained during Sanitary Surveys;" or would "not support the requirement... beyond a simple checklist." One of the commenters suggested "instead that US EPA requires a minimum frequency of 3 to 5 years for primacy agencies to conduct a review of CCT and WQP data and allow the primacy agency to determine how and when this review is conducted." Another commenter suggested "provid[ing] flexibility to states on how to accomplish reviewing corrosion control and water-quality parameters at water systems," and that EPA "could provide flexibility in the rule by not linking the review directly to the sanitary survey and instead establish the review on a three-year frequency giving states the ability to perform the review as part of the sanitary survey or by having a special site visit to perform the review."
One commenter did not support the proposed review during sanitary surveys, stating their belief that it would "not [be] the appropriate format to evaluate whether or not the process being used is providing optimal CCT" and that "[t]he system should be responsible for completing a review of their CCT process, and submitting documentation of such to the State."
One commenter suggested that EPA "develop or at least allow states to use a different mechanism for periodic OCCT reviews rather than limiting that method to sanitary surveys" and claimed it "would be another opportunity to gain efficiencies and reduce costs." The commenter also suggested mandating the review only "for systems with 90th percentile lead levels above 5 ppb." Another also supported mandating reviews based on 90th percentiles but instead suggested using the trigger level.
Some commenters raised the additional burden to primacy agencies as a concern and a challenge, noting that the proposed sanitary survey reviews would require additional training and staffing. Another commenter suggested EPA provide guidance to states on sanitary survey requirements.
One commenter noted the proposal to require consideration of any "updated EPA guidance on CCT during the sanitary survey" and believed it to be "impracticable and likely unenforceable." The commenter suggested "EPA reconsider and clarify its position in EPA's response to comments, including an indication of whether and when amendments to the sanitary survey requirements in § 141 will include requirements specific to the LCR or the LCRR." The commenter also stated their position that the proposed "evaluation is more appropriate as an in-house engineering review" and that "requiring an in-depth review of corrosion control treatment and optimal water quality parameters as part of a sanitary survey could be duplicative for states that utilize investigation staff for conducting sanitary surveys and engineering staff to evaluate corrosion control treatment performance."
A final commenter noted "acceptable methods and instrument calibration" as implementation challenges that may arise during the evaluation of corrosion control during sanitary surveys and suggested that "[v]ery clear regulation needs to be established as to acceptable methods of pH monitoring for process control." The commenter claimed that "many systems use field-based equipment to monitor and control [optimal corrosion control treatment]" and that most small systems encountered by the commenter "do not properly monitor pH." The commenter also sought clarity on whether any deficiencies observed during a sanitary survey evaluation would be considered a treatment technique violation or a monitoring violation.
Agency Response
EPA agrees that an evaluation of CCT processes and WQPs should be included in the sanitary survey as part of the overall review of all treatment processes in use and the monitoring of those processes. EPA notes that large systems will continue to be required to report WQ parameters to the state. EPA disagrees with comments that such a CCT evaluation should not be part of sanitary surveys . As with all other chemical application processes in a public water system, a sanitary survey would determine if the approved or designated treatment is still operational and adequately maintained and monitored. EPA agrees with commenters that this review could be conducted separately on a recurring schedule provided that the review in the results of sanitary survey and completed with the required frequency for sanitary surveys . EPA notes that the current requirements for sanitary surveys allow for a phased approach to completion of each of the required eight elements. There is considerable flexibility for states in organizing and implementing a sanitary survey program including how and when to evaluate OCCT and compliance with WQPs within the required survey frequency time period. In response to comment regarding different primacy agency staff or programs reviewing CCT , EPA again notes that the requirements for sanitary surveys allow for considerable flexibility in completing the required eight elements and different elements or components of those elements could be reviewed by more than one state program component to satisfy sanitary surveys requirements.
The sanitary survey program requirements for states allow for flexibility in completing the required eight elements including a phased approach to completing the required eight elements. As suggested by commenters, the requirement for an evaluation of treatment processes and compliance with water quality parameters could be satisfied as part of other state oversight processes.
EPA agrees with commenters that a full review of OCCT including adjustment of WQPs could necessitate a more focused review. As noted above, the sanitary survey requirement adds the designated CCT process to the review of all other treatment processes. EPA notes that the state may review and modify its OCCT determination and WQPs when it concludes that such a change is necessary to ensure the system continues to optimize corrosion control treatment
With regard to the comments regarding using a different mechanism than a sanitary survey to evaluate EPA does not agree with comments that reviews by states should be limited based on trigger levels or 90[th] percentile lead levels. LCRR requires systems to continuously maintain OCCT where applicable and routine oversight for that requirement is appropriate and consistent with the requirements for sanitary surveys.
EPA acknowledges the challenges for states in implementing the LCRR. EPA plans to continue its training efforts for states including the elements of the LCRR and sanitary surveys. EPA has initiated planning for development of implementation support documents.
EPA does not agree with the comment that a consideration of EPA guidance in LCRR oversight by states is impractical. EPA routinely updates guidance documents to assist states in implementing the NPDWRs. Th referenced language references consideration and does not set any other requirements. Given that is only requirement and that guidance documents do not set any requirements, EPA does believe the issues on enforceability is applicable. With regard to the comment for a need for revision to existing regulatory language for sanitary surveys to address LCRR, EPA has made necessary revisions to ensure OCCT is evaluated. Review of LCRR compliance including OCCT, is within the scope of the required eight elements of a sanitary survey. EPA believes including the review of the required elements of the LCRR in a sanitary survey program is feasible. With regard to the comment regarding deficiencies found related to LCRR, if a water system was found to be not providing OCCT as designated by the state at any time it would be in violation of the treatment technique requirements of the LCRR and if the system failed to complete required monitor at any time it would be in violation of the monitoring requirements of the LCRR.
The same commenter noted the importance of accurate pH measurement as part of LCRR compliance and OCCT. EPA notes that there are approved EPA methods(EPA 150.1, EPA 150.2) for the measurement of pH. Feld measurements of pH are allowed in performed by water system personnel as approved by the state. A review compliance measurements and instrumentation calibration would be a part of a comprehensive sanitary survey.
References
Sandvig, A., P. Kwan, P.E., G. Kirmeyer, P.E., Dr. B. Maynard, Dr. D. Mast, Dr. R. R. Trussell, P.E., Dr. S. Trussell, P.E., A. Cantor, P.E., MCSD, and A. Prescott. 2008. Contribution of Service Line and Plumbing Fixtures to Lead and Copper Rule Compliance Issues. Denver, Colo.: Awwa Research Foundation. Peer reviewed by AwwaRF Project Advisory Committee.
U.S. Environmental Protection Agency. Revised Optimal Corrosion Control Treatment Evaluation Technical Recommendations for Primacy Agencies and Public Water systems. Office of Water, EPA 816-B-16-003, May 2019.
5 Lead Service Line (LSL) Inventory
In the proposed rule, EPA requested comments on the lead service line (LSL) inventory in § 141.84(a), specifically, EPA requested comment on:
       The feasibility of creating initial LSL inventories by the compliance date, which is three years after publication of the final rule, and if a different frequency (other than annual) would be more appropriate for inventory updates.
       Additional requirements or guidance are needed relating to the content or format of inventories.
       The actions that systems with limited records can take to improve their understanding of the number and location of LSLs in their water system.
       Galvanized pipe in LSL inventories and in goal-based and mandatory lead service line replacement (LSLR) rates under the proposed Lead and Copper Rule revisions (LCRR) as well as on the treatment of unknown service lines in the inventory.
       Requiring systems with LSLs to make publicly available the exact address of the LSL in the inventory instead of a location identifier (street, intersection, landmark) as proposed.
Commenters provided a range of perspectives regarding the inventory requirements, such as which systems should create an inventory and how prescriptive the requirements should be. EPA received many comments regarding the requirements and limitations on the information sources that may form the basis for the LSL inventory. Commenters also gave their perspective on the deadline to submit the initial inventory, the frequency of inventory updates, and whether the rule should include a final deadline by which all lead status unknown service lines must be verified. Commenters also had comments regarding the overall burden to create an inventory. Finally, commenters gave recommendations regarding making the inventory publicly accessible as well as whether to include addresses in the inventory.
5.1 General Comments
Summary of Comments
Many commenters offered overall support for the inventory requirements, noting that creating inventories is an essential step towards reducing lead in drinking water. Commenters stated they affirm EPA's proposal to require water systems to prepare and maintain an inventory to identify locations where LSLs are present. One commenter representing a water system stated support for the requirement for a publicly available inventory, stating that the commenter's customers expect this information is known and made available to them. Many other commenters also noted the importance of public access for providing transparency and building customer trust. One commenter stated that a public facing LSL inventory will likely enhance public engagement and potentially lead to customer willingness to replace LSLs. One commenter supports requirements for public water systems (PWSs) to develop complete inventories of their distribution system, including both the private and public side for all service lines no matter the material. One commenter strongly supports LCRR provisions that would encourage community water supplies to expedite the completion of their inventories where states have already established this requirement. One commenter stated that knowing where LSLs exist, a utility can set priorities, better coordinate system upgrade work and provide notice to customers should they choose to replace their LSL during the utility's planned projects. Providing advance notice and communicating to the public, the commenter said, would be one tool to help reduce the potential need to perform partial replacements during routine or planned utility work. A commenter expressed support for all water systems to create an inventory of all water system-owned and customer-owned LSLs in its distribution system and noted "This conforms to provisions Congress included in Section 2015 of the America's Water Infrastructure Act of 2018 directing EPA to develop an assessment of LSLs on public and private property in the next round of the 2020 Drinking Water Infrastructure Needs Survey." A commenter expressed support for requiring "unknown" service lines to be considered as lead, and to provide customers with information stating that they might have an LSL and with the requirement to continuously update the inventory as additional information becomes available. Two commenters said that schools should be required to create an inventory.
Many commenters agreed with the need for LSL inventories, but suggested modifications to the proposed requirements. For example, EPA should require that the water system categorize each service line and explicitly include "unknown" lines in inventory, given that the proposed rule considered unknowns to be LSLs. Another commenter, however, expressed concern that providing customers with an annual notification that they may have an LSL when its material is unknown has the potential to cause unnecessary anxiety and distrust of PWSs. This commenter recommended that the notification process to customers of unknown service lines be delayed until fewer unknowns are in the inventory. One commenter urged EPA to require an LSL inventory, that acknowledges the multiple lead-bearing components that can lie between a service line and a home's internal plumbing and transparency for access to LSL information including where lead lines exist in their communities.
Several commenters recommended that the rule waive the LSL inventory requirements under certain conditions. One commenter suggested that small systems with reasonable knowledge that they have no LSLs based on date of construction and historical monitoring data with 90[th] percentiles below 5 ppb (i.e., ug/L) should not be required to develop an LSL inventory. Commenters suggested that PWSs with no LSLs or that have replaced all their LSL should be able to certify to the primacy agency that they have no LSLs, and would notify the primacy agency if an LSL is found during main replacement or maintenance (if the LSL was previously reported as non-lead). One commenter asserted that a waiver process that requires the system to submit an application is burdensome on the system and state, especially if the system was constructed past the ban of lead piping but has no records or an easy way to confirm the service line materials for the inventory.
Other commenters recommended that the final rule continue to emphasize that the LSL inventory is to be based on available information and improved over time in the course of routine system activities. Commenters state that the rule must recognize that there will be uncertainty in which pipe materials are present but make clear that water systems should be transparent as to the basis for the inventory when presenting it to the public.
A commenter suggested that generally lead was not used for larger-diameter service lines and suggested the final rule limit inventories to certain diameter service lines and to exclude irrigation, fire lines, and other non-potable service lines. One commenter supported the proposed requirements for small water systems to develop the LSL inventory and plan but noted funding like the Drinking Water State Revolving Fund (DWSRF) may be needed. One commenter supported LSL inventory development for medium and large water systems, but not for small systems as they do not have adequate resources.
While many commenters acknowledged the importance of identifying the areas in the distribution system that contain lead, several highlighted the burden associated with creating an inventory. One commenter representing a water system estimated the cost to conduct service line inventories on the system-owned portion would range from $1.1 to $1.3 million, while identifying the customer-owned portion would cost between $19 to $21 million and be highly disruptive to customers. Another commenter noted that inventory requirements will also burden the states, who would likely provide technical assistance and trainings, as well as additional funding. Many commenters noted the significant cost and burden associated with developing an LSL inventory might require that resources from other PWS work be redirected.
Some commenters expressed concern that the proposal was overly prescriptive, forcing a "one-size-fits-all" approach for systems that vary greatly (e.g., in terms of size, infrastructure age, and materials used). One commenter said that the proposal lacked a mechanism for addressing erroneous service line composition assignments.
Some commenters raised concerns about LSL inventories given that the customer owns their side of the service line and the PWS must gain permission for access to these lines to complete the inventory. Other commenters expressed concern with the ability of PWSs to obtain customer cooperation, asserting that EPA must address and clarify how utilities contact customers and building owners that are non-responsive to notification and request for access or investigation.
One commenter suggested that "centralized state databases should also show the location of water systems that are not covered by the Safe Drinking Water Act." The commenter said that "water systems not regulated under the Safe Drinking Water Act (SDWA), and therefore not subject to the regulations of the LCR, include water systems serving an estimated 98,000 schools and 500,000 childcare providers nationwide." The commenter also suggested that "states may also make information available regarding any local regulations that exist for these water systems."
Some commenters requested clarification for what requirements apply to systems with no LSLs as well as how customer ownership of LSLs affects the inventory requirements. Other commenters requested guidance from EPA on inventory development. A commenter suggested that EPA define what is expected of the inventory in terms of documentation and acceptable methods of determining whether pipes and other plumbing components contain lead.
Agency Response
For the final rule, EPA is requiring that all community water systems (CWSs) and non-transient, non-community water systems (NTNCWSs) create an inventory, regardless of water system size, characteristics, service line ownership, or historical tap sampling results. EPA acknowledges there is burden associated with creating and updating service line inventories. An inventory, however, is the foundation of the final LCRR as many provisions rely on an awareness and an accounting of LSL locations. For example, identifying the locations of all known and potential LSLs is needed for compliance with the requirement to notify persons served by LSLs in § 141.85(e) and to calculate how many service lines must be replaced under a goal or mandatory LSLR program under § 141.84(a). One key aspect of this treatment technique rule is public education (PE), including PE about the sources of lead in drinking water. Even when a system is at or below the lead action level based on tap sampling, there can be very high lead levels in water delivered to specific locations within the system, particularly locations served by LSLs. The requirement to notify those persons served by an LSL will give those customers information critical to their decision-making with respect to mitigating their risk of exposure to water that may contain high amounts of lead, especially in light of the fact that the rule does not require widespread tap sampling in any system. Even very small water systems, which some commenters suggested be exempt due to the burden of creating an inventory, must rely on an inventory to comply with numerous rule provisions that require knowledge of known or potential LSL locations. EPA disagrees with the commenters that said water systems with low historical lead levels should be exempt from inventory requirements because they claim there is less risk of lead exposure from their systems. As mentioned above, individual service lines may show higher lead levels even when systemwide lead levels appear low. In addition, these systems are still subject to provisions requiring an accounting of LSLs that apply regardless of system-wide calculations of lead levels, namely the requirement discussed above to notify persons served by LSLs in § 141.85(e). Water systems that state they have no LSLs must also create an inventory in order to provide documented evidence to support their claim. It is therefore essential that all regulated PWSs create an inventory and that no water systems have inventory requirements waived.
EPA determined it is practicable and feasible for water systems to prepare the initial inventory by the rule compliance date, three years after rule promulgation as not every service line composition need be determined and may be identified as lead status unknown. It is important that water systems complete the initial LSL inventory within three years of publication of the final rule to facilitate selection of tap sampling sites under new tiering criteria and informing consumers about the presence of an LSL by the compliance date for those provisions, which is based on Section 1412(b)(10) of the SDWA. The inventory is critical to determining the number of LSLs to be applied to the LSLR rate under a lead trigger level exceedance and action level exceedance.
Initial LSL inventories will be updated and submitted to states annually or triennially, in sync with the systems tap sample monitoring period but no more frequently than annually. EPA recognizes that service line material classifications may change as new records are discovered, through normal water system operations, or as physical inspections or replacements are conducted, and therefore allows water systems to update the inventory over time. EPA recommends a disclaimer stating that the inventory content is subject to change with new information, so inventory users understand how to interpret the information. There is no deadline for a water system to compile a complete inventory (i.e., one that does not include any service lines of unknown materials). This means that the water system can comply with the inventory requirements in the final rule even if service line materials remain unverified, for example due to customers who are non-responsive or unwilling to allow system personnel to inspect the service line (if an in-home inspection is even needed).
EPA disagrees that the final rule requirements are overly prescriptive or that they force a "one-size-fits-all" approach for all systems. The final rule establishes minimum requirements for the inventory, including the sources that must be reviewed under § 141.84(a)(3) and the classifications under § 141.84(a)(4). The final rule does not prescribe material identification techniques used to develop the inventory over time, inventory format, or the specific type of location identifier the system chooses to use in its publicly available inventory. See response to comment Section 5.4 for a discussion of the minimum requirements for making the inventory publicly available.
Many commenters requested guidance on how to create an inventory. EPA understands that rule guidance is a critical component to ensure the rule's effectiveness in protecting public health. The Agency intends to develop implementation guidance targeting the areas of the rule that are most likely to support compliance. In addition to guidance, EPA will also provide training and other supporting materials that will help states and water systems implement the revised rule and promote greater national consistency.
One commenter asked EPA to clarify how to inventory service lines which split or branch from a single system-owned portion into multiple buildings. Each split or branched service connection from the system-owned portion would be considered a service line and should be included in the inventory.
In response to the commenter that recommended that schools should be required to have LSL inventories, EPA notes that schools that are regulated PWSs will be subject to the inventory requirements under the final rule. SDWA authorizes EPA to regulate PWSs as defined in Section 1401(4). Water systems will list all service lines in their inventory, which includes those which serve schools that are not PWSs. EPA notes that LSLs were generally used to serve single family homes, while schools are often larger structures whose service line is likely made of a non-lead material.
5.2 Timeframe to Submit Initial Inventory/Update Inventory
Initial Inventory Deadline of Three Years After Rule Publication
Summary of Comments
Several commenters thought that it was feasible to create an initial inventory in three years, mentioning examples of water systems and states that were successful in doing so. A commenter noted that any system that has been required to replace LSLs in the past as a result of a lead action level exceedance should already have initial inventory information, due to the previous rule requirement for systems to replace 7 percent of their LSLs. In addition, the commenter noted the February 2016 memo from EPA Assistant Administrator for Water to state SDWA primacy agency directors requested that materials inventories required under the original Lead and Copper Rule (LCR) -- as well as updated information on LSLs -- be posted on water system or state agency website, with a priority for large systems (USEPA, 2016).
A few commenters suggested EPA should consider a shorter timeframe for initial inventory completion, such as one or two years after rule promulgation, because they claim it is feasible for a majority of systems, would benefit the public by being made available sooner, and is needed to ensure the initial inventory is complete if LSLR is triggered at the rule effective date. One commenter argued that "[c]onducting an inventory within one year is "feasible" within the meaning of the SDWA" because "EPA's own regulations and state laws demonstrate that it is "feasible" for water systems to conduct a full LSL inventory with one year of initial rule promulgation." The commenter claims that § 141.84(b)(1) of "[t]he current rule requires water systems with existing corrosion control treatment to identify the full number of lead service lines in their distribution systems within one year of an action level exceedance" and, as a practical matter, it requires systems "to complete a full lead service line inventory within a few months in order to meet the rule's requirement to replace seven percent of the "initial number" of lead service lines in the distribution within one year of exceeding the action level." Therefore, according to the commenter, the three-year timeframe in the LCRR "is insufficiently protective of public health" and "EPA must require water systems to complete lead service line inventories within one year of the final rule's publication, to ensure that the agency's final standards protect the public against "adverse health impacts . . . to the extent feasible" [42 U.S.C. § 300g-1(b)(7)(A).] This commenter also argued that EPA violates Section 706(2)(A)and (C) of the Administrative Procedure Act because EPA did not explain why the LCRR provides systems three years to complete an initial inventory given that "[a]ll systems are currently required, in certain circumstances, to count the full number of lead service lines in their distribution systems within a year under the Lead and Copper Rule and have done so in the past. [See 40 C.F.R. § 141.84(b)(1).] Several states require water systems to perform full lead service line inventories within one year or less."
One commenter suggested that the initial LSL inventory should be developed and submitted to the primacy agency in a staggered time frame from small, medium, to large water systems, recommending the following timeframes: small one year, medium two years, and large three years.
Other commenters claimed the three-year deadline is not feasible. A commenter suggested the initial inventory should be submitted five years after final rule publication, while other commenters suggested six, seven, and ten years. A commenter noted that its water system has been developing an accurate inventory for two years; however, the customer side is only 37 percent complete. A commenter noted that requiring an initial inventory within three years may force most systems with limited budgets and personnel to create inventory lists with large numbers of unknown lines and will most likely not be very accurate. Commenters noted the significant effort required to create an inventory and conduct a thorough records search where records may be missing or inaccessible, or in a paper format which makes information time-consuming to compile. Some commenters noted that small systems that often lack capacity and are financially constrained will have difficulty producing an inventory and replacement plan within the proposed three-year timeline, and that these systems should be granted additional time to comply with the inventory requirements. Another commenter said that large systems should be granted more time as they have more service connections and potentially more records to investigate. Another commenter suggested that all water systems should have the ability to receive an extension for initial inventory submission. Some commenters suggested requiring initial LSL inventory for the public side of the distribution system within three years, while allowing five years or more for the private side, depending on system size. Staggering the submittal timeframes for LSL inventories, another commenter noted, will stagger initial tap sampling, alleviating a capacity crisis at laboratories that could otherwise occur as a result of large numbers of samples being submitted for laboratory analysis all at once. Some commenters appeared to judge feasibility of creating an initial inventory as equal to completing an inventory with all service line materials verified, although the proposed rule did not require this.
One commenter stated that three years was sufficient time to create the initial inventory, however recommended that states should be allowed one year to review the inventories before water systems submit updated compliance sampling location plans based on these inventories. The commenter noted that early implementation of the inventory creates issues by preventing the "development of appropriate inventory guidance and the development of a functional data management system for inventories." One commenter noted that water systems will be compiling inventories while states are operating under early implementation agreements or the rule will be directly implemented by EPA. To complicate matters further, the commenter said, EPA does not typically release implementation guidance until six months or even years after a rule is promulgated. If EPA guidance or state actions after promulgation revise expectations for how inventories will be prepared or presented, a commenter stated, then systems will be unable to meet the required deadline. One commenter suggested that EPA should develop and provide guidelines for systems concurrently with the posting of the new rule, most importantly, with stakeholder input. Another commenter noted that guidance should provide detailed information to assist water systems in addressing issues such as customer engagement and how the inventory is updated. Yet another commenter recommended EPA delay implementation of the mapping and inventory compliance obligations until primacy is attained to ensure consistent application of requirements in a unilateral direction for a given state. If EPA does not allow state-driven flexibility, the commenter said, then inventory compliance deadlines should be postponed until three years after the date of EPA guidance documents for this effort are finalized.
Some commenters suggested staggering the timeframes to submit the initial inventory to reduce state burden to review all initial inventories simultaneously. This burden could also stagger tap sampling for water systems, alleviating a purported "capacity crisis" at laboratories responding to a large number of samples. Commenters asked for the final rule to allow states to grant an extension to water systems that require additional time for inventory completion. Another commenter proposed that if a system can demonstrate a "B3" status to the state prior to final promulgation of the LCRR, the system may be eligible for a state-approved extension to complete the materials inventory (e.g., longer than three years, but within six years).
Agency Response
While EPA acknowledges that a review of existing records specified in § 141.84(a)(3) may require significant effort for some water systems, the Agency disagrees that three years is not feasible. The previous rule requires a service line materials inventory, meaning water systems will have already begun to compile information to populate inventory contents, and all water systems who have exceeded the lead AL under the previous LCR would have collected service line material information within one year after exceeding the lead AL so it could remove at least 7 percent of the LSLs in its distribution system. As EPA noted in the preamble to the proposed rule (USEPA, 2019), several states have already required water systems, including small systems, to create LSL inventories. For example, Michigan required an initial inventory in one and a half years and Ohio required initial inventory completion in as little as six months. EPA also disagrees that water systems should be allowed to receive an extension to comply with the initial inventory requirements because it is feasible to conduct a review of records and make the results publicly accessible within three years. The records which need be searched are explicitly stated in the final rule. These records include information on lead and galvanized iron or steel that may have been identified to comply with the requirement under § 141.42(d), as well as construction and plumbing codes, permits and records that indicate service line materials, water system records (i.e., distribution system maps and drawings, historical records on each service connection, meter installation records, historical capital improvement or master plans, and standard operating procedures), inspections and records of the distribution system that indicate service line material composition, as well as any resource, information, or identification method as provided or required by the state to assess service line materials. Furthermore, stakeholder collaboratives have compiled resources and techniques for creating an inventory which may quicken inventory development. As noted above, many water systems have already created inventories, through proactive efforts or via the previous LCR or state laws.
Timely creation of the initial inventory is critical to other aspects of the final LCRR, providing the foundation for compliance with tap sampling, PE, LSLR, and other provisions. Therefore, EPA determined that initial inventory completion within three years is not only feasible but also critical to comply with the final LCR, regardless of a whether a system has very low lead 90[th] percentile levels (i.e., is a B3 system). Thus, the Agency has retained this requirement from the proposed rule for the final rule.
To support water systems' ability to achieve a three-year deadline to create the initial inventory, the rule provides flexibility in terms of the inventory format. Water systems can choose an inventory format, such as a simple list or table, that will minimize burden (for more information about inventory format, see EPA's response to comment Section 5.6) except that § 141.84(a)(8) provides that water systems serving over 50,000 people must make the inventory available online. While EPA recommends that inventories be user-friendly, water systems may continue to develop and enhance the inventory format over time after creating a simpler, compliant initial inventory within three years.
EPA noticed that some commenters incorrectly interpreted the proposed rule requirements, believing verification of all lead status unknown service lines was required within three years. Neither the proposed nor final rules require any deadline to verify all unknowns. Systems conducting LSLR will have an incentive to verify the material of all unknown lines because they will be treated as LSLs in calculating the number of lines that must be replaced, but the rule will not require that verification by a set date.
EPA disagrees with commenters who suggested that the final rule require submission of the initial or a complete inventory in less than three years after publication of the final rule. First, EPA notes that the existing LCR remains applicable in the 3-year period between this final rule's publication date and the requirement to comply with the new inventory requirements in the LCRR. This means that the requirements in § 141.84(b)(1) and § 141.90(e)(1) will apply during that interim period and therefore, systems triggered into LSLR after an action level exceedance will need to identify the initial number of LSLs in their distribution system at the time the system exceeds the lead action level. Second, the new inventory requirements are different than the existing inventory requirements: they apply to all systems, not just those that are conducting LSLR in response to an action level exceedance and they call for an inventory that is different and broader than the inventory needed to implement the LSLR program in the previous rule. EPA expects that many systems will need more than one year to compile an inventory that meets the requirements of the final rule and to prepare the inventory to be made available to the public. Further, water systems will need to inventory full service lines  -  the portion owned by the system and the portion owned by the customer, not just the system-owned portion of the line. In addition, the final rule's initial inventory requires "galvanized requiring replacement" service lines to be classified as such if they are or ever were downstream of an LSL, which is different from the previous rule. The final rule's inventory requirements may be more complicated than it would have been when the LCR was first promulgated in 1991 (USEPA, 1991) now that many systems have conducted partial LSLRs. (If a service line has been partially replaced, the inventory under the LCRR will need to cover two parts of the service line for that address.) EPA further notes that the relevant records may be difficult for some water systems to obtain as these records may not be centrally maintained and may require further investigation to assure their accuracy. Finally, prior to the initial inventory deadline, systems will be engaged in both maintaining compliance with the previous LCR and working towards compliance with several deadlines in the revisions to the rule.
EPA also disagrees with the commenter's suggestion that EPA has changed its determination regarding the feasibility of the inventory requirement without providing a rationale. Section 1412(b)(10) of the SDWA provides that a National Primary Drinking Water Regulation (NPDWR)  -  and any amendment of an NPDWR  -  "shall take effect on the date that is three years after the date on which the regulation is promulgated unless the Administrator determines that an earlier date is practicable." This three-year time frame provides states with time needed to update their regulations and submit primacy revisions to EPA. Consistent with that provision of SDWA, EPA's proposed rule included a compliance deadline that is three years after promulgation of the regulation, which is the date of publication. EPA has considered the comments advocating an earlier compliance deadline for the inventory, but for the reasons described above, EPA finds that it would not be practicable for systems to comply with the amended inventory requirements earlier than the standard three-year time frame provided in Section 1412(b)(10) of the SDWA.
EPA disagrees that states should have one year to review the initial inventories. An added year for inventory review would create significant delays in final rule implementation.
One commenter suggested that rather than submitting the entire LSL inventory to the state, a state may request water systems provide an indication where changes have occurred from the previous inventory submitted, as this may ease their review, for example when few changes have occurred at a system with a large number of service lines. EPA agrees this would be acceptable in the regulatory text of the final rule. For EPA's response to comments about data management systems, please see response to comment Section 15.
Inventory Update Frequency
Summary of Comments
Commenters noted that because knowledge about LSL locations evolves over time, inventories must be regularly updated to reflect any changes. One commenter viewed annual inventory updates as essential. One commenter advocated for the mandatory update of the LSL inventory every five years if systems have LSLs and that more frequent updates should be voluntary. Another commenter believed that the inventory updates should be submitted to the primacy agency every three years and more frequently than annually on the water systems website. Yet another commenter suggested that the inventory should be updated every three years with the sanitary survey. One commenter suggested that the LSL inventory should be updated as replacements occur.
Some commenters suggested that the final rule align state inventory update submissions with the water system's tap sampling monitoring period, but not more frequently than annually. This submission schedule would be more efficient, commenters argued, because water systems would not be required to provide an update when there haven't been a significant number of LSLRs, such as when the system is on reduced monitoring not conducting an LSLR program.
Commenters also suggested clarification of the inventory update requirements for water systems that do not have LSLs. One commenter noted that many NTNCWSs are buildings with internal plumbing only. Some commenters suggested waiving LSL inventory updates when the inventory shows no remaining LSLs or lead status unknown service lines, and to update the inventory only if a service line originally thought to be non-lead is discovered to be an LSL, and is not subsequently replaced. According to these commenters, this type of update requirement could prevent unnecessary burden for the water system to submit and the state to review an inventory which has not changed due to complete LSLR.
Some commenters also requested that states have the flexibility to require submission of a complete inventory that includes updates or just a submission identifying revisions to the initial inventory. This would reduce the burden for the state reviewing the inventory to target their review solely on the aspects of the inventory that have changed since the previous review.
A commenter noted that enforcement workload could increase with frequent inventory update requirements due to water systems failing to submit their inventory updates.
Agency Response
EPA agrees with commenters' suggestions to align inventory update submission frequency with the tap sampling monitoring period and revised the regulatory text accordingly in the final rule. EPA agrees with this approach as it will reduce burden yet at the same time ensure that the inventory is updated more frequently in cases where there are likely to be more revisions, such as when a system is conducting LSLR and therefore monitoring more frequently. Inventories will likely undergo more change as a result of LSLR requirements that water systems are subject to after exceeding the lead trigger level (TL) and AL. This approach is efficient and reduces burden to both the water system submitting the inventory and to the state reviewing it. Water systems on 6-month monitoring are only required to submit an update annually, given that LSLR rates apply based upon a 2 year rolling average. Water systems on triennial tap sampling monitoring periods would submit inventory updates every three years.
In addition to the updates to the state, water systems must also update the public-facing LSL inventory in the final rule no less frequently than when required to be submitted to the state. This change from the proposed rule ensures that the public also has access to the most up-to-date version of the inventory. The update schedule for the publicly available inventory is identical to the system's monitoring period for the same reasons as described in the paragraph above for the updated schedule for reporting to the state. In addition, it would be unnecessarily complicated and confusing for a system to update the inventory provided to the state and the inventory provided to the public on two different schedules. EPA encourages but does not require the public-facing inventories to be updated more frequently than required in the rule so the public is kept up-to-date about the water system's progress to identify and replace LSLs.
For the final rule, EPA incorporated commenter suggestions to allow water systems to cease providing inventory updates to the state and public should the inventory show only non-LSLs. This change will eliminate unnecessary burden for the water system to submit and the state to review inventory updates for a distribution system which has been confirmed to contain no LSLs. Should an LSL be discovered in the future, the water system is required to notify the state of the discovery.
Deadline to Verify All Lead Status Unknown Service Lines
Summary of Comments
Some commenters stated that the final rule should include a deadline for the water system to achieve 100 percent verification of all service line materials. Such a deadline, commenters argued, would ensure that lead status unknown service lines would undergo materials composition verification in a timely manner, providing verification results to consumers potentially served by an LSL. Commenters noted that other states require a verification deadline, such as Michigan water systems by 2025.
A commenter suggested the final inventory identifying all unknown service lines should be required to be completed two years after the initial inventory submission. Another commenter suggested a deadline of five years after the initial inventory submission. Another commenter wrote that primacy agencies should be given the ability to impose deadlines for water systems to verify service line materials based on system-specific situations and system capacity. One commenter indicated that the rule should include a provision that states may require a verification deadline within the rule.
Agency Response
The final rule acknowledges that the inventory is an ongoing effort and does not set an affirmative deadline for complete verification of service line material composition for all service lines. Due to the widely different circumstances facing water systems, EPA is unable to set an inventory development deadline in the final rule. For systems with limited records, individual service lines may rely on more burdensome visual investigation techniques, such as hydrovacing or viewing the service line in the meter pit. For these systems, a deadline set at the federal level would likely be infeasible. For other systems with very few lead status unknown service lines, a federal deadline would likely not reflect the ability of the water system to identify its remaining unknowns in a much shorter timeframe, which may discourage or unnecessarily prolong the water system's inventorying efforts. EPA determined that a more appropriate approach to ensuring continued inventory development progress is to provide incentives in the final rule for verifying unknowns as well as by requiring that service line materials be tracked in the inventory when the water system encounters service lines, such as during existing water system activities. The rule incentives allow water systems to cease sending PE to consumers whose lead status unknown service lines are non-lead pursuant to § 141.85(e), to stop issuing risk mitigation notification to unknowns that are non-lead pursuant to § 141.85(f), and to subtract unknowns that are non-lead from the calculation of annual goal or mandatory LSLR rate pursuant to § 141.84(a)(7). This approach has the benefit of incentivizing consistent inventory development progress while accounting for the different circumstances that water systems face.
Inventories will be continually updated over time because the final rule requires that systems identify and track service line materials as they are encountered. In addition, the final rule includes a new requirement in the LSLR plan that mandates that water systems outline their strategy for determining the material composition of lead status unknown service lines. For more explanation about the LSLR plan requirements in the final rule, please see response to comment Section 6.
EPA notes that individual states may establish verification deadlines in their own LCR, such as the State of Michigan. Also, states may establish LCRR requirements that are more stringent than the NPDWR.
5.3 Inventory Scope
Summary of Comments
Commenters had many perspectives regarding which types of service lines and other lead sources should be included in the inventory. Some commenters suggested that the final rule's inventory include only service lines used for potable purposes. Commenters noted that an LSL used for non-potable purposes poses no exposure risk to humans. Commenters highlighted service lines intended for fire suppression or agricultural uses as examples of service lines that should not be included in the inventory.
Some commenters believed that focus on any service lines that are not known LSLs, such as unknowns and galvanized service lines, could detract from efforts to inventory and replace known LSLs.
Many commenters supported the inclusion of customer-owned service lines in the inventory. One commenter requested that EPA provide guidance related to inventorying customer-owned service lines. Some commenters agreed that the water system should prepare an inventory but thought the water system should not be required to investigate or inventory the customer-owned portion of the service line, noting they are often not under the system's control. One commenter said that their water system lacks records for the customer-side and that building permit issuing agencies are more likely to have the pipe material information on the customer side and are in a better position to identify the material on that portion of the service line. Commenters noted that classification of the customer-owned service line may require customer cooperation or engagement, which could prevent the water system from learning its material if, for example, the customer is non-responsive, refuses to allow the system access to private property, or does not alert the system if they replace their portion. A commenter said that water systems should be able to document refusals or non-responses by customers to investigate the customer-owned portion. One commenter stated that their water system lacks the authority to enter customer property other than to check the meter. One commenter said that inventorying customer-owned LSLs would be a multi-year effort with no public health benefit. Another customer suggested EPA conduct a cost-benefit analysis of including the customer-owned service lines versus excluding them from the inventory. Another commenter said including customer-owned service lines in the inventory is not an appropriate use of rate payers' money because it benefits an individual and not the system. Many commenters believed that identifying and disclosing lead plumbing inside or serving a home should be left to real estate agencies, and home buyers and sellers. One commenter suggested a waiver option for agencies without lead or unknown service lines to complete inventory of private customer service lateral material of construction. The commenter went on to say at a maximum, the requirement should allow customer self-reporting as compliance with inventory development when the agency's inventory does not contain LSLs. One commenter said that the state should create a customer self-reporting or self-monitoring system for customer-owned service lines.
Many commenters generally supported EPA's decision to include lead status unknown service lines in the inventory until determined to be otherwise so that a water system may have a "complete" initial inventory, even if it lacks material composition records for every service line in its distribution system. One commenter expressed concern that allowing "unknowns" in the inventory would disincentivize water systems from completing the inventory.
Some commenters said that lead status unknown service lines should not be included in the inventory. They claimed that a high number of lead status unknown service lines, especially on the customer side, could raise alarm among members of the public. Commenters also mentioned that water systems often lack authority to enter private property, which could make service line material investigations more challenging to conduct. A commenter suggested that unknowns be excluded from the inventory because it may not be possible to investigate their material where a customer is unwilling. One commenter said that investigation of the customer-side could expose a system to customer claims and litigation over alleged liability and property damage. A commenter stated that if the customer refuses to allow the water system to investigate a customer service line whose material is unknown, the line should not be used to calculate LSLR rates, as other unknowns are.
Some commenters noted that although they have large numbers of unknowns in their distribution system, they know that LSLs are not widespread. One commenter asked for tiered inventory criteria, with less stringent requirements for systems that are unlikely to have LSLs. Commenters recommended that additional classifications for unknowns be introduced, such as "unknown -- not lead," disagreeing that because a service line material is "unknown" it should automatically be presumed to be a potential LSL. Some commenters suggested that unknowns should not be labeled as a "lead service line" in the inventory as it could cause confusion. Some commenters expressed support for statistical models that have been used by some water systems to determine the probability that an unknown is actually an LSL. One commenter suggested that unknowns be included on a case-by-case basis dependent on the water system's history. A commenter recommended that unknowns that consistently test low for lead levels should not be considered LSLs. One commenter suggested that unknowns be tracked separately with a goal rate that unknowns are investigated. Another commenter suggested a cutoff to the number of unknowns that are considered LSLs.
Although not included in the proposal, some commenters stated they did not see the need to identify the specific material of the service line if it could be proven to be non-lead (e.g., copper or plastic pipe). Another commenter said that the final rule and subsequent guidance should encourage water systems to work to identify the material of all service lines on both the public and private sides, even if it is not an LSL.
Some commenters requested that lead goosenecks, pigtails, and connectors (connectors) should be considered as LSLs in the inventory because they are a source of lead in drinking water infrastructure. Some commenters supported their inclusion but called for them to be included separately from LSLs. Others thought that these connectors should not be included in the inventory given the burden to identify their material composition and that the inventory should focus on LSLs.