Drinking water sampling is necessary to quantify lead release from service lines and premise plumbing sources. Selecting the appropriate sampling method can meaningfully address a given lead sampling goal, including regulatory compliance, corrosion control assessment, lead sources identification, or residential lead exposure assessment. The objective of this work was to compare water sampling lead results from multiple sampling approaches in homes with and without lead service lines (LSLs) in two cities in the United States (US): one with and one without effective corrosion control. These approaches included targeted stagnation first liter (i.e., first draw), fifth liter, fully flushed, sequential profile, manual composite, random daytime, and an innovative passive sampling device. In the city with effective corrosion control (orthophosphate addition), regardless of sampling approach, homes with and without LSLs could not be differentiated based on lead concentration results. However, in the city with ineffective corrosion control, large lead differences between homes with and without LSLs existed with every sampling approach. For example, exposure based manual composite samples had 15 times more lead in homes with LSLs as compared to non-LSL homes based on mean levels 6.9 versus 0.45 μg/L). Lead concentration thresholds based on mean fifth liter sampling results (2× multiplication factor) had 100 % accuracy in determining LSL and non-LSL homes in that city. In addition, lead exposure was reduced by a factor of 5.8 based on mean lead concentrations (6.9 versus 1.2 μg/L) in drinking water collected according to the exposure-based manual composite sampling approach. An innovative passive sampling device for assessing long-term lead exposure was successfully demonstrated in homes for the first time. Interestingly, the long-term exposure results based on the device were similar to the short-term manual composite exposure sampling results, although more data are needed across homes and cities. The findings of this study expand the industry's knowledge and perspective on water sampling for lead, to aid with LSL identification, residential exposure assessment and other goals.

ABSTRACT Inventorying and replacing lead service lines (LSLs) is a national priority in the United States (US), with records review conducted as a first step. Among other records, historical plumbing codes can provide cutoff dates for LSL allowance in the US. This work identified and reviewed historical National Plumbing Codes for mention of lead for drinking water pipe and found that lead pipe was permissible for service lines by the Basic Plumbing Code until 1978, the Uniform Plumbing Code until 1988, and the Southern Standard Plumbing Code until 1977/78. Overall, identifying pertinent code titles over time and obtaining them was challenging because those records were not readily available. Once obtained, interpreting the code language also proved challenging. Terminology initially reflected sanitary systems before drinking water systems were incorporated, and code editions through the years reorganized the content and specific mentions of lead in service lines within text. This review focused on model plumbing codes, which are then adopted at the state or local level, typically with modifications that also need to be understood. Two practical examples of service line inventory development were also summarized. These examples highlighted placing different emphasis on plumbing code review.

Water lead measurements by two field analyzers, relying on anodic stripping voltammetry (ASV) and fluorescence spectroscopy, were compared to reference laboratory measurements by inductively coupled plasma mass spectrometry (ICP-MS) in progressively complex datasets (phases A, B, C), to assess field analyzer performance. Under controlled laboratory quantitative tests of dissolved lead within the field analysis range and optimal temperature range, lead recoveries by ASV ranged within 85-106 % of reference laboratory values (corresponding linear model: y = 0.96x, r2 = 0.99), compared to lower lead recoveries of 60-80 % by fluorescence (y = 0.69x, r2 = 0.99) in phase A. Field analyzer performance deteriorated in three opportunistic laboratory datasets compiled for phase B that contained dissolved lead (ASV: y = 0.80x, r2 = 0.98; no fluorescence data). Further lead underestimations were observed in five field datasets compiled for phase C, some of which contained known particulate lead (ASV: y = 0.54x, r2 = 0.76; fluorescence: y = 0.06x, r2 = 0.38). Deteriorating performance between phases was presumably due to the increasingly complex water matrices and lead particulates present in some phase C subsets (phase A < phase B < phase C). Phase C field samples had lead concentrations that were out-of-range, including a 5 % and 31 % false negative rate by ASV and by uorescence, respectively. The range of results relevant to the diverse nature of compiled datasets, suggests that unless ideal conditions are known to be present (i.e., the lead content of water is dissolved within the eld analysis range and optimal water temperature range), these eld lead analyses might only be used as a water screening tool. Given the unknown conditions in many eld settings, combined with the lead concentration underestimations including the false negative rates reported herein for eld datasets, caution is encouraged when employing ASV and particularly uorescence eld analysis.

Bench top and pilot lead corrosion studies are gaining more interest, considering revisions and upcoming improvements to the Lead and Copper Rule. This literature review identified studies ranging from simpler month(s)-long bench top dump-and-fill stagnant water tests (coupon tests/standing pipe tests) to more complicated year(s)-long intermittent flow pilot studies (recirculating pipe loops/once through pipe rigs). With increasing complexity in design and operation, studies more closely approximated real plumbing conditions (e.g., by incorporating harvested lead pipes and intermittent flow regimes) at increased cost, footprint, and duration. Comparison of bench top and pilot designs (in terms of lead test piece age/dimensions/configuration/replicates, study duration, sample collection, and other factors) can assist drinking water utilities, consultants, academics, and others to select a design that matches their needs and constraints. No matter the choice, surrogate systems cannot replace actual system water testing and are best complemented by other corrosion assessment tools.

Key TakeawaysUnder the Lead and Copper Rule Long‐Term Revisions, community water systems must establish an inventory of their lead service lines (LSLs); thus, the material used for every service line must be identified.Developing, using, and managing an LSL inventory involves multiple steps, resources, and components, and the resulting information needs to be accurate.An AWWA subcommittee interviewed 10 water systems to learn about their processes for LSL inventory creation, material identification, customer communication, and other aspects of their experiences.

With lead service lines (LSLs) remaining for decades to come, scale analyses are critical to helping limit lead exposure from drinking water. This laboratory has used an integrated suite of analytical techniques to characterize the elemental composition, mineral identification, and physical features of scales, helping the water industry to evaluate, predict, and reduce lead corrosion. The methods used in this laboratory to prepare and analyze the LSL scale, and guidance to achieving reliable and meaningful results, are described. Primary methods include the following: optical microscopy, powder X-ray diffraction, inductively coupled plasma spectroscopy, X-ray fluorescence, scanning electron microscopy with energy dispersive spectroscopy, combustion and coulometric analyses of C and S, and X-ray absorption spectroscopy. Examples of associated pitfalls and ways to avoid them are provided, including pipe excavation/transport, sample preparation, analysis, and data interpretation. Illustrative examples are presented of practical scale analysis questions that could be answered by combinations of pipe scale analyses.

Copper pitting is a significant but preventable cause of drinking water plumbing failure.

Lead service lines (LSLs) represent the greatest source of lead in drinking water. Identifying the locations of LSLs can be challenging, and recent service line (SL) material surveys in Michigan, Illinois, Wisconsin, and Indiana found that on average the materials making up 16% of SLs in these states are unknown and may be lead. Given the large number of possible LSLs in the United States, new and pending regulatory requirements, LSL replacement costs, associated lead exposure risks, and the public's desire to reduce lead exposure, there is a need to rapidly and cost-effectively identify where LSLs are located, on public and private property. This review summarizes current industry LSL identification methods, including records screening, basic visual examination of indoor plumbing, water sampling, excavation, and predictive data analyses. A qualitative comparison of method cost, accuracy, disturbance, and other impacts is provided as a starting point for utilities that are developing a feasible approach for their specific needs/constraints. Lastly, an example stepwise approach to identify unknown SL materials is proposed.

There are many sampling approaches available for lead (Pb) in drinking water. Selecting the best approach for its intended use is critical. The objective of this work was to compare water Pb levels collected by multiple sampling approaches from a model home plumbing system (HPS) that included an old Pb service line (LSL), as a function of daily water usage. Specifically, flushed, direct LSL, sequential profile, random daytime (RDT), first draw, and manual composite samples were compared, and daily water usage rates ranged from 1.4 to 120 gallons/day (5.3-454.2 L/day). Pb levels in water collected directly from the LSL reached equilibrium after 7-15.5 h of stagnation, and approximately 55% of the equilibrium Pb concentration was reached after 2 h. Sequential sampling accurately identified the LSL; however, the peak profile Pb concentrations were a fraction of the Pb measured directly from the LSL. Daily water usage patterns greatly impacted total Pb levels in all water sampling approaches, although manual composite and RDT samples were more sensitive to changes. Manual composite and RDT samples were equal to or greater than first draw samples throughout the study, and differences grew larger as water usage decreased.

Copper corrosion is affected by a wide variety of environmental conditions in a water system. Proper evaluation approaches are key to helping utilities prevent corrosion.

Lead (Pb) in drinking water has re-emerged as a modern public health threat which can vary widely in space and in time (i.e., between homes, within homes and even at the same tap over time). Spatial and temporal water Pb variability in buildings is the combined result of water chemistry, hydraulics, Pb plumbing materials and water use patterns. This makes it challenging to obtain meaningful water Pb data with which to estimate potential exposure to residents. The objectives of this review paper are to describe the root causes of intrinsic Pb variability in drinking water, which in turn impacts the numerous existing water sampling protocols for Pb. Such knowledge can assist the public health community, the drinking water industry, and other interested groups to interpret/compare existing drinking water Pb data, develop appropriate sampling protocols to answer specific questions relating to Pb in water, and understand potential exposure to Pb-contaminated water. Overall, review of the literature indicated that drinking water sampling for Pb assessment can serve many purposes. Regulatory compliance sampling protocols are useful in assessing community-wide compliance with a water Pb regulatory standard by typically employing practical single samples. More complex multi-sample protocols are useful for comprehensive Pb plumbing source determination (e.g., Pb service line, Pb brass faucet, Pb solder joint) or Pb form identification (i.e., particulate Pb release) in buildings. Exposure assessment sampling can employ cumulative water samples that directly capture an approximate average water Pb concentration over a prolonged period of normal household water use. Exposure assessment may conceivably also employ frequent random single samples, but this approach warrants further investigation. Each protocol has a specific use answering one or more questions relevant to Pb in water. In order to establish statistical correlations to blood Pb measurements or to predict blood Pb levels from existing datasets, the suitability of available drinking water Pb datasets in representing water Pb exposure needs to be understood and the uncertainties need to be characterized.

Field analyzers for the measurement of lead in drinking water samples are gaining interest from states, water utilities and building managers as rapid, inexpensive and simple tools to quantify lead concentrations. This literature review compares data quality by field analyzers to established laboratory methods and provides practical information (e.g. costs, ease-of-use) on commercial lead analyzers that are based on: (1) Electrochemistry, (2) Colorimetry and (3) Fluorescence. Between and within these three general field analyzer categories, manufacturers specify a variety of protocols to prepare the samples, which differ from the standard acidification in laboratory methods. Review of the literature raised concerns that without adequate sample preparation, field analyzers may not always fully quantify the total lead concentration, including particulate lead, thereby resulting in underestimations. Nonetheless, field analyzers have been used to quickly obtain experimental results in the laboratory, or in the field when access to laboratory equipment was limited, expensive or otherwise impractical. Field analyzers were also successfully used to detect lead from service lines, by a water utility where lead was mostly in the dissolved form. Overall, intrinsic strengths and weaknesses of field analyzers are discussed, to better balance practical convenience and adequate data quality depending on the objective.

Orthophosphate (PO4) addition is a common corrosion control treatment used to lower lead (Pb) concentrations at the consumer's tap by forming relatively insoluble Pb-phosphate (Pb-PO4) minerals. However, some Pb-PO4 particles that can form in drinking water are mobile nanoparticles (i.e., 0.001-0.1 µm) that have the potential to reach the tap. Point-of-use (POU) or pitcher filters are often used to manage risks during distribution system upsets, when corrosion control treatment is not optimized, or following Pb service line replacements. To abide by industry convention, POU and pitcher filters must be NSF/ANSI-certified for Pb reduction (NSF/ANSI-53) using a test water containing dissolved Pb and large Pb particles. Certification for particulates reduction (NSF/ANSI-42) is done using a test water that contains particles, but not leaded particles. To address the lack of testing for Pb nanoparticles, this study challenged six certified commercially available faucet-mounted POU (3) and pitcher (3) filters with aqueous suspensions of Pb-PO4 nanoparticle. For the water quality investigated, the Pb particles formed ranged between 0.016 and 0.098 µm, based on scanning electron microscopy, transmission electron microscopy, and dynamic light scattering analysis. These particles represented 98.5% of total Pb in suspension. The total Pb removals were between 44.6 and 65.1% for the POU filters, and between 10.9 and 92.9% for the pitcher filters. The electron microscopy results confirm that Pb-PO4 nanoparticles passed through the filters. The findings can inform future efforts to re-examine the test waters used in the certification challenge tests.

Opportunistic pathogens such as Legionella are of significant public health concern in hospitals. Microbiological and water chemistry parameters in hot water throughout an Ohio hospital were monitored monthly before and after the installation of a monochloramine disinfection system over 16 months. Water samples from fifteen hot water sampling sites as well as the municipal water supply entering the hospital were analyzed using both culture and qPCR assays for specific microbial pathogens including Legionella, Pseudomonas spp., nontuberculous Mycobacteria [NTM], as well as for heterotrophic bacteria. Legionella culture assays decreased from 68% of all sites being positive prior to monochloramine addition to 6% positive after monochloramine addition, and these trends were parallel to qPCR results. Considering all samples, NTMs by culture were significantly reduced from 61% to 14% positivity (p<0.001) after monochloramine treatment. Mycobacterium genus-specific qPCR positivity was reduced from 92% to 65%, but the change was not significant. Heterotrophic bacteria (heterotrophic bacteria plate counts [HPCs]) exhibited large variability which skewed statistical results on a per room basis. However, when all samples were considered, a significant decrease in HPCs was observed after monochloramine addition. Lastly, Pseudomonas aeruginosa and Vermamoeba vermiformis demonstrated large and significant decrease of qPCR signals post-chloramination. General water chemistry parameters including monochloramine residual, nitrate, nitrite, pH, temperature, metals and total trihalomethanes (TTHMs) were also measured. Significant monochloramine residuals were consistently observed at all sampling sites with very little free ammonia present and no water quality indications of nitrification (e.g., pH decrease, elevated nitrite or nitrate). The addition of monochloramine had no obvious impact on metals (lead, copper and iron) and disinfection by-products.

There is great interest in producing nanoparticles for various applications. The objective of this work was to develop a procedure for reproducibly creating stable lead (Pb) phosphate nanoparticle aqueous suspensions. A stable 5 mg/L Pb-phosphate nanoparticle "stock" suspension was synthesized via chemical precipitation of Pb and orthophosphate in water at pH 7.5 with 4.4 mg soluble PO4/L and 7 mg C/L dissolved inorganic carbon. The stock suspension was subsequently diluted to produce stable 0.10 mg/L Pb "challenge" water suspensions without compromising the nanoparticle size, structure, mineralogy and solubility. Specifically, the hexagonal hydroxypyromorphite nanoparticles had an average diameter of 38 nm based on transmission electron microscopy analysis and an associated Pb solubility of 0.001 mg/L. The properties of the stock suspensions were not impacted by further dilutions, and the challenge water suspensions remained stable for 24 hours. In the context of drinking water, a protocol to produce such a stable Pb nanoparticle challenge water suspension would be very useful in evaluating Pb bioavailability, identifying Pb remediation strategies, and testing filter effectiveness to remove Pb from water.

The lead contamination of drinking water in homes and buildings remains an important public health concern. In order to assess strategies to measure and reduce exposure to lead from drinking water, models are needed that incorporate the multiple factors affecting lead concentrations in premise plumbing systems (PPS). In this study, the use of EPANET, a commonly used hydraulic and water quality model for water distribution systems, was assessed for its ability to predict lead concentrations in PPS. The model was calibrated and validated against data collected from multiple experiments in the EPA's Home Plumbing Simulator that contained a lead service line and other lead sources. The EPANET's first-order saturation kinetics model was used to simulate the dissolution of lead in the lead service line. A version of EPANET was developed to include one-dimensional mass dispersion. Modeling results were compared to experimental data, and recommendations were made to improve the EPANET-based modeling framework for predicting lead concentrations in PPS.

A retrospective analysis of 20 water systems from the U.S. Environmental Protection Agency's Arsenic Demonstration Program demonstrated three patterns of arsenic levels at the tap after arsenic treatment of the source well water. Following an initial destabilization period, Pattern A systems (6/20 with low iron/manganese in source water and plastic piping) had arsenic concentrations that did not change as water traveled to consumer taps (conservative contaminant behavior). Pattern B systems (8/20 with high iron/manganese in source water and iron piping) had consistently higher arsenic concentrations at consumer taps, above the arsenic content of incoming treated water, for months to more than a year after arsenic treatment (nonconservative behavior). Pattern C systems (6/20 with additional occasional arsenic treatment complications) experienced multiple arsenic spikes at consumer taps (nonconservative and unpredictable behavior). These field observations suggest that, in some water distribution systems, arsenic may linger long after it has been removed at its source.

Legionellosis, manifesting as either Legionnaires’ disease or Pontiac fever, is a serious concern in the United States. Water providers and property owners must do their part to control Legionella.

Various drinking water sampling approaches can be taken to assess the presence of lead in drinking water. Water utilities should consider using diagnostic sampling to help identify lead sources.