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Complexities associated with drinking water plumbing systems can result in undesirable interactions among plumbing components that undermine engineering controls for opportunistic pathogens (OPs). In this study, we examine the effects of plumbing system materials and two commonly applied disinfectants, copper and chloramines, on water chemistry and the growth of Legionella and mycobacteria across a transect of bench- and pilot-scale hot water experiments carried out with the same municipal water supply. We discovered that copper released from corrosion of plumbing materials can initiate evolution of >1100 times more hydrogen (H 2 ) from water heater sacrificial anode rods than does presence of copper dosed as soluble cupric ions. H 2 is a favorable electron donor for autotrophs and causes fixation of organic carbon that could serve as a nutrient for OPs. Dosed cupric ions acted as a disinfectant in stratified stagnant pipes, inhibiting culturable Legionella and biofilm formation, but promoted Legionella growth in pipes subject to convective mixing. This difference was presumably due to continuous delivery of nutrients to biofilm on the pipes under convective mixing conditions. Chloramines eliminated culturable Legionella and prevented L. pneumophila from recolonizing biofilms, but M. avium gene numbers increased by 0.14-0.76 logs in the bulk water and were unaffected in the biofilm. This study provides practical confirmation of past discrepancies in the literature regarding the variable effects of copper on Legionella growth, and confirms prior reports of trade-offs between Legionella and mycobacteria if chloramines are applied as secondary disinfectant residual.

Variability in the concentration of lead and copper sampled at consumers' taps poses challenges to assessing consumer health threats and the effectiveness of corrosion control. To examine the minimum variability that is practically achievable, standardized rigs with three lead and copper containing plumbing materials (leaded brass, copper tube with lead solder, and a lead copper connection) were deployed at five utilities and sampled with regimented protocols. Variability represented by relative standard deviation (RSD) in lead release was high in all cases. The brass had the lowest variability in lead release (RSD = 31 %) followed by copper-solder (RSD = 49%) and lead-copper (RSD = 80%). This high inherent variability is due to semi-random detachment of particulate lead to water, and represents a modern reality of water lead problems that should be explicitly acknowledged and considered in all aspects of exposure, public education, and monitoring.

A pilot experiment examined lead leaching from four representative configurations of service lines including: (1) 100% lead (Pb), (2) 100% copper (Cu), (3) 50% Pb upstream of 50% Cu, and (4) 50% Pb-downstream of 50% Cu using a range of flow rates. The cumulative mass of lead release indicated that a typical partial replacement configuration (50% lead downstream of copper) did not provide a net reduction in lead when compared to 100% lead pipe (85 mg for 50% Pb-downstream versus 83 mg for 100%-Pb) due to galvanic and deposition corrosion. The partially replaced service line configuration also had a much greater likelihood of producing water with "spikes" of lead particulates at higher flow rates, while tending to produce lower levels of lead at very low flow rates. After the first 214 days the galvanic current between copper and lead was only reduced by 34%, proving that galvanic impacts can be highly persistent even in water with optimized corrosion control by dosing of zinc orthophosphate. Finally, this experiment raises concern about the low flow rates used during some prior home sampling events, which may underestimate exposure to lead during normal water use, especially when galvanic Pb:Cu connections are present., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

The lead leaching potential of new brass plumbing devices has come under scrutiny as a significant source of lead in drinking water (>300 μg/L) of new buildings around the world. Experiments were conducted using ball valves that were sold as certified and known to have caused problems in practice, in order to better understand how installed products could create such problems, even if they passed "leaching tests" such as National Sanitation Foundation (NSF) Standard 61 Section 8. Diffusion of lead from within the device into water when installed can increase lead leaching by orders of magnitude relative to results of NSF testing, which once only required exposure of very small volumes of water within the device. "Normalization" of the lead-in-water result tended to produce estimates of lead concentration that were much lower than actual lead measured at the tap. Finally, the presence of flux could also dramatically increase lead leaching, whereas high water velocity had relatively little effect., (Copyright © 2012. Published by Elsevier Ltd.)

Taste and odor issues occurring in new buildings were attributed to rapid loss of chloramine residual, high levels of microbes in the potable water system, and high water age due to use of advanced water conservation devices. Laboratory experiments confirmed that chloramine could decay rapidly in the presence of new copper pipe, providing a possible explanation for the rapid disinfectant loss in the new buildings. Higher temperature and lower pH also accelerated the rate of chloramine decay in copper pipes. The reaction was slowed by the addition of phosphate inhibitor or aluminum, which presumably formed barriers between the pipe wall and the chloramine in the bulk water. Additional research is needed to better understand how to maintain high quality water in buildings while also conserving water., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

A rapid reaction between free chlorine and the cupric hydroxide [Cu(OH)2] solids commonly found on pipe walls in premise plumbing can convert free chlorine to chloride and rapidly age Cu(OH)2 to tenorite (CuO). This reaction has important practical implications for maintaining free chlorine residuals in premise plumbing, commissioning of new copper pipe systems, and maintaining low levels of copper in potable water. The reaction stoichiometry between chlorine and Cu(OH)2 is consistent with formation of CuO through a metastable Cu(III) intermediate, although definitive mechanistic understanding requires future research. Natural levels of silica in water (0-30 mg/L), orthophosphate, and higher pH interfere with the rate of this reaction., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

As stagnant water contacts copper pipe and lead solder (simulated soldered joints), a corrosion cell is formed between the metals in solder (Pb, Sn) and the copper. If the resulting galvanic current exceeds about 2 μA/cm(2), a highly corrosive microenvironment can form at the solder surface, with pH < 2.5 and chloride concentrations at least 11 times higher than bulk water levels. Waters with relatively high chloride tend to sustain high galvanic currents, preventing passivation of the solder surface, and contributing to lead contamination of potable water supplies. The total mass of lead corroded was consistent with predictions based on the galvanic current, and lead leaching to water was correlated with galvanic current. If the concentration of sulfate in the water increased relative to chloride, galvanic currents and associated lead contamination could be greatly reduced, and solder surfaces were readily passivated.

Cu is an antimicrobial that is commonly applied to premise (i.e., building) plumbing systems for Legionella control, but the precise mechanisms of inactivation are not well defined. Here, we applied a suite of viability assays and mass spectrometry-based proteomics to assess the mechanistic effects of Cu on L. pneumophila. Although a five- to six-log reduction in culturability was observed with 5 mg/L Cu2+ exposure, cell membrane integrity only indicated a <50% reduction. Whole-cell proteomic analysis revealed that AhpD, a protein related to oxidative stress, was elevated in Cu-exposed Legionella relative to culturable cells. Other proteins related to cell membrane synthesis and motility were also higher for the Cu-exposed cells relative to controls without Cu. While the proteins related to primary metabolism decreased for the Cu-exposed cells, no significant differences in the abundance of proteins related to virulence or infectivity were found, which was consistent with the ability of VBNC cells to cause infections. Whereas the cell-membrane integrity assay provided an upper-bound measurement of viability, an amoebae co-culture assay provided a lower-bound limit. The findings have important implications for assessing Legionella risk following its exposure to copper in engineered water systems. [ABSTRACT FROM AUTHOR]

Objectives: Reports of unsafe school drinking water in the United States highlight the importance of ensuring school water is safe for consumption. Our objectives were to describe (1) results from our recent school drinking water sampling of 5 common contaminants, (2) school-level factors associated with exceedances of various water quality standards, and (3) recommendations. Methods: We collected and analyzed drinking water samples from at least 3 sources in 83 schools from a representative sample of California public schools from 2017 through 2022. We used multivariate logistic regression to examine school-level factors associated with lead in drinking water exceedances at the American Academy of Pediatrics (AAP) recommendation level (1 part per billion [ppb]) and state action-level exceedances of other contaminants (lead, copper, arsenic, nitrate, and hexavalent chromium). Results: No schools had state action-level violations for arsenic or nitrate; however, 4% had ≥1 tap that exceeded either the proposed 10 ppb action level for hexavalent chromium or the 1300 ppb action level for copper. Of first-draw lead samples, 4% of schools had ≥1 tap that exceeded the California action level of 15 ppb, 18% exceeded the US Food and Drug Administration (FDA) bottled water standard of 5 ppb, and 75% exceeded the AAP 1 ppb recommendation. After turning on the tap and flushing water for 45 seconds, 2%, 10%, and 33% of schools exceeded the same standards, respectively. We found no significant differences in demographic characteristics between schools with and without FDA or AAP exceedances. Conclusions: Enforcing stricter lead action levels (<5 ppb) will markedly increase remediation costs. Continued sampling, testing, and remediation efforts are necessary to ensure drinking water meets safety standards in US schools. [ABSTRACT FROM AUTHOR]

Key Takeaways: Because it can accumulate lead in its scale, galvanized iron pipe (GIP) poses compliance challenges in the Lead and Copper Rule Revisions (LCRR) and proposed Lead and Copper Rule Improvements (LCRI). To prepare for the LCRR/LCRI, utilities can use the GIP corrosion control toolbox outlined here, including targeted sampling, scale analysis, and corrosion control treatment testing. GIP investigation and management can improve water quality, protect public health, and minimize aesthetic discoloration issues. The proposed LCRR/LCRI tap sampling changes mean that GIP could contribute to Action Level exceedances for the first time. [ABSTRACT FROM AUTHOR]

Deposition corrosion, via formation of microgalvanic cells from copper ions (e.g., Cu[I], Cu[II]) on iron or galvanized (zinc-coated) steel pipe, has been linked to disastrous field corrosion failures. Key factors expected to control deposition corrosion, including soluble copper concentration, copper ion speciation, and flow pattern (stagnant versus recirculating), were examined. The mass of copper plating was directly proportional to the soluble copper concentration in solution. The presence of flow, which allowed greater mass transport of reactants to the pipe surface, proved to be crucial to replicating deposition corrosion in the laboratory: tests with flow demonstrated up to 7x more zinc release and 55x more iron release when copper was present than when it was absent, compared to increases of only ≈2x in the same water under stagnant conditions. Scale dissolution, x-ray fluorescence, and scanning electron microscopy were used to characterize copper-rich deposits on the surface of both field and laboratory samples that were consistent with metallic copper, supporting a deposition corrosion mechanism. [ABSTRACT FROM AUTHOR]

Deposition corrosion has been identified as a possible factor contributing to consumer exposure to elevated lead in water after partial lead service line replacement. Dump-and-fill tests in two different waters yielded very different results; compared with the control, one water showed a substantial increase (approximately three times) in lead leaching, whereas the other showed little effect when copper was added to water contacting new lead pipes. These differences were consistent with expected trends; lead leaching increased as both the copper solubility in water and the amount of copper deposited on the lead pipe surface increased. Detailed analyses of lead pipes from laboratory studies and field tests in which lead was galvanically connected to copper using various commercial and laboratory connectors were consistent with pure metallic copper deposits on the pipe surface, especially near the galvanic junction with copper. This finding supports a significant deposition corrosion mechanism when copper and lead are galvanically connected. [ABSTRACT FROM AUTHOR]

A new elementary school with persistent elevated copper corrosion by-product release evaluated pH increase, orthophosphate dosing, and granular activated carbon (GAC) treatment as potential corrosion control measures using bench-scale experiments. Removal of natural organic matter (NOM) with temporary GAC treatment facilitated the formation of a copper scale with a permanently diminished (> 85%) solubility via an accelerated natural scale-aging process. Increasing the pH and adding a high dose of orthophosphate were also effective for decreasing copper release but presented significant long-term drawbacks, and their benefits were reversed if the treatments were discontinued. Temporary GAC treatment may be a holistically attractive option to reduce copper corrosion problems in new construction in certain waters with high levels of NOM. [ABSTRACT FROM AUTHOR]

Abstract: Effects of plumbing-specific installation factors on brass corrosion were investigated in a series of pipe-loop experiments. Increased flow velocity increased corrosion rates, but did not affect corrosion type. The presence of copper tubing in the plumbing system increased selectivity of brass corrosion for zinc, unless a galvanic connection was made between copper and brass, in which case corrosion became more uniform and was accelerated. Plastic tubing allowed oxidant (i.e., free chlorine) to persist in water, increasing brass exposure. Additionally, hot water significantly increased lead leaching from brass. These findings may inform future investigations into brass corrosion issues and plumbing designs. [Copyright &y& Elsevier]

Nitrification and granular activated carbon (GAC) filtration impact leaching of lead/copper to potable water under typical home plumbing configurations. GAC filters removed the disinfectant and caused rapid establishment of nitrification in chloraminated systems. The potential adverse consequences of whole house GAC filters deserve increased scrutiny in chloraminated systems. The lower pH values from nitrification and other microbes during overnight stagnation in pipes can markedly increase (up to 800%) lead and copper contamination of water. [ABSTRACT FROM AUTHOR]

Both aluminium solids and chlorine are often present in potable water systems, but their effect on copper corrosion and pitting is not well understood. Circumstantial evidence from one system with copper pitting problems suggested that high chlorine residuals and aluminium solids might be contributing factors. To test this hypothesis, a series of experiments were conducted to examine their effect on copper corrosion under stagnant and flow conditions. Although chlorine alone impacted copper corrosion, a synergistic reaction was discovered between chlorine and aluminium solids when exposed to copper. Evidence for this effect was seen in increased chlorine decay rates, increased non-uniform copper corrosion, and rising corrosion potentials during exposure. It is likely this reaction is involved in copper pit initiation. [Copyright &y& Elsevier]

Experiments were conducted to determine the effect of sustained temperature gradients of ≈20 °C on copper pipe corrosion under stagnant conditions in simulated potable water. An apparatus was constructed to (1) apply realistic temperature gradients to the pipes, (2) monitor copper release to the water, and (3) measure thermogalvanic currents between the warm and cold sections of pipe. The orientation of the pipe in relation to the temperature gradients determined whether convection currents developed that promoted mixing during stagnation, and this influenced the magnitude of the temperature gradient in the pipe. The temperature gradient led to significant sustained thermogalvanic currents. Mixing of the water within the pipe also influenced copper leaching and scale build-up. [Copyright &y& Elsevier]

This paper examines the important, and oftentimes dominant, role of particles in lead and copper corrosion by-product release from stagnant pipes. For copper pipes, orthophosphate generally reduced soluble copper levels compared to pipes with no inhibitor but had little effect on particulate copper, while pipes dosed with polyphosphate generally had higher levels of particulate copper, probably due to the formation of a less durable copper–phosphate solid. For lead, the vast majority of lead by-products were particulate, and particulate release in low pH and low alkalinity waters was associated with hydrocerrusite scales. Orthophosphate and polyphosphate tended to decrease particulate lead species, possibly due to the formation of a lead–phosphate solid. For both lead and copper pipes, zinc orthophosphate did not show any significant advantages compared to orthophosphate alone, generally due to the increased release of particulate lead or copper species which may be associated with a zinc–phosphate precipitate. Finally, the occurrence of particulate and colloidal species, especially lead, was confirmed by utility tap water sampling. [ABSTRACT FROM AUTHOR]

Copper corrosion by-product release to potable water is a complex function of pipe age, water quality, stagnation time, and type of phosphate inhibitor. Moderate (&ap;1 mg/l as P) doses of polyphosphate or orthophosphate generally decreased copper release in pipe rig tests of >3 years duration. The exception was pH 7.2 and alkalinity 300 mg/l as CaCO3, in which phosphate dosing significantly increased copper release over long time periods by hindering the formation of relatively insoluble malachite scale. Dosing of polyphosphates, which is invariably a blend of orthophosphate and polyphosphate due to reversion, was not as beneficial as orthophosphate. These relative effects are consistent with expectations based on simplistic solubility models, in which copper complexation by polyphosphate tends to increase soluble copper release, whereas higher doses of orthophosphate tend to decrease copper solubility. [Copyright &y& Elsevier]

Growth of Legionella pneumophila and other opportunistic pathogens (OPs) in drinking water premise plumbing poses an increasing public health concern. Premise plumbing is constructed of a variety of materials, creating complex environments that vary chemically, microbiologically, spatially, and temporally in a manner likely to influence survival and growth of OPs. Here we systematically review the literature to critically examine the varied effects of common metallic (copper, iron) and plastic (PVC, cross-linked polyethylene (PEX)) pipe materials on factors influencing OP growth in drinking water, including nutrient availability, disinfectant levels, and the composition of the broader microbiome. Plastic pipes can leach organic carbon, but demonstrate a lower disinfectant demand and fewer water chemistry interactions. Iron pipes may provide OPs with nutrients directly or indirectly, exhibiting a high disinfectant demand and potential to form scales with high surface areas suitable for biofilm colonization. While copper pipes are known for their antimicrobial properties, evidence of their efficacy for OP control is inconsistent. Under some circumstances, copper's interactions with premise plumbing water chemistry and resident microbes can encourage growth of OPs. Plumbing design, configuration, and operation can be manipulated to control such interactions and health outcomes. Influences of pipe materials on OP physiology should also be considered, including the possibility of influencing virulence and antibiotic resistance. In conclusion, all known pipe materials have a potential to either stimulate or inhibit OP growth, depending on the circumstances. This review delineates some of these circumstances and informs future research and guidance towards effective deployment of pipe materials for control of OPs. [ABSTRACT FROM AUTHOR]

Flint, MI experienced two outbreaks of Legionnaires' Disease (LD) during the summers of 2014 and 2015, coinciding with use of Flint River as a drinking water source without corrosion control. Using simulated distribution systems (SDSs) followed by stagnant simulated premise (i.e., building) plumbing reactors (SPPRs) containing cross-linked polyethylene (PEX) or copper pipe, we reproduced trends in water chemistry and Legionella proliferation observed in the field when Flint River versus Detroit water were used before, during, and after the outbreak. Specifically, due to high chlorine demand in the SDSs, SPPRs with treated Flint River water were chlorine deficient and had elevated L. pneumophila numbers in the PEX condition. SPPRs with Detroit water, which had lower chlorine demand and higher residual chlorine, lost all culturable L. pneumophila within two months. L. pneumophila also diminished more rapidly with time in Flint River SPPRs with copper pipe, presumably due to the bacteriostatic properties of elevated copper concentrations caused by lack of corrosion control and stagnation. This study confirms hypothesized mechanisms by which the switch in water chemistry, pipe materials, and different flow patterns in Flint premise plumbing may have contributed to observed LD outbreak patterns. [ABSTRACT FROM AUTHOR]

• Effects of Cu on L. pneumophila were tested in pilot-scale hot water plumbing rigs. • Scenarios were identified where phosphate and anode rods (Mg or Al) interfered with Cu disinfection. • The strain inoculated in the rigs was found to be highly tolerant of Cu. • The findings identify scenarios where Cu can and cannot control L. pneumophila. Copper (Cu) is sometimes applied as an antimicrobial for controlling Legionella in hot water plumbing systems, but its efficacy is inconsistent. Here we examined the effects of Cu (0 - 2 mg/L), orthophosphate corrosion inhibitor (0 or 3 mg/L as phosphate), and water heater anodes (aluminum, magnesium, and powered anodes) on both bulk water and biofilm-associated L. pneumophila in pilot-scale water heater systems. Soluble, but not total, Cu was a good predictor of antimicrobial capacity of Cu. Even after months of exposure to very high Cu levels (>1.2 mg/L) and low pH (<7), which increases solubility and enhances bioavailability of Cu, culturable L. pneumophila was only reduced by ∼1-log. Cu antimicrobial capacity was shown to be limited by various factors, including binding of Cu ions by aluminum hydroxide precipitates released from corrosion of aluminum anodes, higher pH due to magnesium anode corrosion, and high Cu tolerance of the outbreak-associated L. pneumophila strain that was inoculated into the systems. L. pneumophila numbers were also higher in several instances when Cu was dosed together with orthophosphate (e.g., with an Al anode), revealing at least one scenario where high levels of total Cu appeared to stimulate Legionella. The controlled, pilot-scale nature of this study provides new understanding of the limitations of Cu as an antimicrobial in real-world plumbing systems. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract: Although orthophosphate is often effective in reducing lead corrosion, bench-scale tests revealed cases in which even high doses of orthophosphate (1–3mg/L P) in potable water increased lead and tin release from simulated soldered copper joints. Phosphate increased the galvanic current between tin and copper plumbing materials, especially in water with less than 10mg/L and when the percentage of the anodic current carried by ion was less than 30%. Tin release was increased more than lead release from 50:50 Pb–Sn solder in these circumstances. [Copyright &y& Elsevier]