{"id":{"repo_id":"vt","oai_identifier":"oai:vtechworks.lib.vt.edu:10919/140664"},"canonical_url":"https://search.dev.ndltd.org/etd/vt/oai:vtechworks.lib.vt.edu:10919/140664","repository":{"repo_id":"vt","name":"Virginia Tech","base_url":"https://vtechworks.lib.vt.edu/oai/request"},"display":{"title":"Novel Insights into Lead Corrosion Control: Safely Changing Source Waters, Effective Use of Zinc Phosphate Inhibitors, Electrochemical Reversal of Solder, and Significance of Lead-Polyphosphate Complexation","abstract":"Recent high profile lead contamination events arising from lead solder corrosion have drawn attention to our alarmingly inadequate understanding of corrosion control chemistry. This dissertation provides novel contributions to an improved understanding of lead corrosion control in four sequential chapters that: 1) develop a new framework to proactively evaluate the impact of source water changes on lead solder corrosion, 2) demonstrate that in certain corrosive waters zinc orthophosphate can dramatically reduce lead contamination from solder at pHs around 7.5-9.5, but is ineffective in relatively non-corrosive waters or at pHs outside this range, 3) reveal that prolonged exposure to free chlorine can dramatically reduce lead contamination from solder by causing \"electrochemical reversal,\" protecting solder from galvanic corrosion, and 4) apply a method for measuring problematic lead complexation by polyphosphate, which reveals a significant health concern in some water chemistries but insignificant problems in others. Chapter 2 describes how water utilities are increasingly changing source waters in response to groundwater contamination, sustainability efforts, new regulations, and consolidation. We worked with three communities who unexpectedly experienced very severe lead contamination from lead-tin solder following a seemingly innocuous change in source water. We demonstrate how existing frameworks did not anticipate lead solder corrosion problems because: 1) prolonged exposure to non-corrosive water can preserve lead solder in relatively pristine condition, which is more susceptible to severe corrosion following changes in water chemistry, and 2) prolonged exposure to corrosive water can be self-limiting because all exposed lead in copper pipes could have corroded away within a period of decades, counter-intuitively producing low present day lead contamination in a highly corrosive water. A failure to understand the implications of these scenarios resulted in erroneous logic predicting that a source water change would be safe when it was not. We develop a proactive bench scale testing protocol and improved framework that can allow utilities to avoid similar mistakes in the future. Chapter 3 addresses divergent results regarding the effectiveness of zinc orthophosphate corrosion inhibitor in controlling lead solder corrosion; that is, some research reported remarkable advantages compared to adjusting pH/alkalinity or dosing orthophosphate alone, whereas other research found no benefits. We examined relative performance of zinc orthophosphate at a wide range of pHs (6.5, 7.5, 8.5, 9.5, 10.5) in a low alkalinity, low conductivity water with corrosivity increased by addition of extra chloride or nitrate, and demonstrate that the results depend on water chemistry. Specifically, zinc orthophosphate has little benefit in water with low chloride or nitrate, in which corrosivity is low, at any pH tested. But at higher corrosivity zinc orthophosphate significantly reduced lead release at pH 7.5-9.5, including 40X reductions in lead release at pH 8.5. Yet no relative advantage occurred at pH 6.5 and pH 10.5. Results are consistent with passivation from zinc phosphate precipitation from pH 7.5 to 9.5 as predicted by equilibrium modeling and supported by scale analysis. Similar methods can be used to predict relative performance of inhibitors for controlling lead solder corrosion in other source waters and determine if these results are generalizable. Chapter 4 explores a 40-year-old mystery with profound present-day implications. A study in Portland, Oregon had revealed that free chlorine had orders of magnitude less lead contamination when compared to chloramine, but the result was discounted because chlorine was always believed to be more corrosive than chloramine. Here, we resolve the controversy by demonstrating \"electrochemical reversal\" of the copper-solder galvanic couple in synthesized water similar to Portland's. That is, short-term exposure to chlorine did not reduce lead contamination, but prolonged exposure to free chlorine caused the normally anodic solder to become cathodic via formation of a Pb(IV) scale. This eventually caused free-chlorine treated water to have 10-100X less lead contamination than chloramine-treated water after several months of exposure. This discovery has major implications for water treatment and can also help explain why some waters dosed with free chlorine have anomalously low lead contamination. Chapter 5 examines fears that utilities adding polyphosphates to drinking water to sequester iron and manganese, or to prevent calcium carbonate scaling, will invariably suffer from higher lead solubility and a higher risk of lead contamination. Here, we develop a simple semi-quantitative method using cation exchange resins to evaluate the significance of lead-polyphosphate complexation. Applying this test in a range of waters, we reveal the dependency of lead-polyphosphate complexation on water hardness, polyphosphate dose, and the ratio of orthophosphate to polyphosphate. This approach can be used to predict the impact of a given polyphosphate product and dose on lead complexation, allowing utilities to predict the magnitude of the problem for a given water in about a day. We find a strong linear relationship between polyphosphate dose and complexed lead. Additionally, when >200 mg/L as CaCO3 of calcium is present, >3X less lead-polyphosphate complexation can occur versus when no calcium is present. Our work also demonstrates that testing artifacts probably caused past research to overestimate the danger of the lead complexation problem. This work has significant implications for public health and is timely as water lead contamination is increasingly scrutinized. The simple tests and corrosion control methods described herein can help drinking water utilities make informed water treatment decisions to reduce lead contamination and protect public health.","abstract_html":"Recent high profile lead contamination events arising from lead solder corrosion have drawn attention to our alarmingly inadequate understanding of corrosion control chemistry. This dissertation provides novel contributions to an improved understanding of lead corrosion control in four sequential chapters that: 1) develop a new framework to proactively evaluate the impact of source water changes on lead solder corrosion, 2) demonstrate that in certain corrosive waters zinc orthophosphate can dramatically reduce lead contamination from solder at pHs around 7.5-9.5, but is ineffective in relatively non-corrosive waters or at pHs outside this range, 3) reveal that prolonged exposure to free chlorine can dramatically reduce lead contamination from solder by causing "electrochemical reversal," protecting solder from galvanic corrosion, and 4) apply a method for measuring problematic lead complexation by polyphosphate, which reveals a significant health concern in some water chemistries but insignificant problems in others. Chapter 2 describes how water utilities are increasingly changing source waters in response to groundwater contamination, sustainability efforts, new regulations, and consolidation. We worked with three communities who unexpectedly experienced very severe lead contamination from lead-tin solder following a seemingly innocuous change in source water. We demonstrate how existing frameworks did not anticipate lead solder corrosion problems because: 1) prolonged exposure to non-corrosive water can preserve lead solder in relatively pristine condition, which is more susceptible to severe corrosion following changes in water chemistry, and 2) prolonged exposure to corrosive water can be self-limiting because all exposed lead in copper pipes could have corroded away within a period of decades, counter-intuitively producing low present day lead contamination in a highly corrosive water. A failure to understand the implications of these scenarios resulted in erroneous logic predicting that a source water change would be safe when it was not. We develop a proactive bench scale testing protocol and improved framework that can allow utilities to avoid similar mistakes in the future. Chapter 3 addresses divergent results regarding the effectiveness of zinc orthophosphate corrosion inhibitor in controlling lead solder corrosion; that is, some research reported remarkable advantages compared to adjusting pH/alkalinity or dosing orthophosphate alone, whereas other research found no benefits. We examined relative performance of zinc orthophosphate at a wide range of pHs (6.5, 7.5, 8.5, 9.5, 10.5) in a low alkalinity, low conductivity water with corrosivity increased by addition of extra chloride or nitrate, and demonstrate that the results depend on water chemistry. Specifically, zinc orthophosphate has little benefit in water with low chloride or nitrate, in which corrosivity is low, at any pH tested. But at higher corrosivity zinc orthophosphate significantly reduced lead release at pH 7.5-9.5, including 40X reductions in lead release at pH 8.5. Yet no relative advantage occurred at pH 6.5 and pH 10.5. Results are consistent with passivation from zinc phosphate precipitation from pH 7.5 to 9.5 as predicted by equilibrium modeling and supported by scale analysis. Similar methods can be used to predict relative performance of inhibitors for controlling lead solder corrosion in other source waters and determine if these results are generalizable. Chapter 4 explores a 40-year-old mystery with profound present-day implications. A study in Portland, Oregon had revealed that free chlorine had orders of magnitude less lead contamination when compared to chloramine, but the result was discounted because chlorine was always believed to be more corrosive than chloramine. Here, we resolve the controversy by demonstrating "electrochemical reversal" of the copper-solder galvanic couple in synthesized water similar to Portland's. That is, short-term exposure to chlorine did not reduce lead contamination, but prolonged exposure to free chlorine caused the normally anodic solder to become cathodic via formation of a Pb(IV) scale. This eventually caused free-chlorine treated water to have 10-100X less lead contamination than chloramine-treated water after several months of exposure. This discovery has major implications for water treatment and can also help explain why some waters dosed with free chlorine have anomalously low lead contamination. Chapter 5 examines fears that utilities adding polyphosphates to drinking water to sequester iron and manganese, or to prevent calcium carbonate scaling, will invariably suffer from higher lead solubility and a higher risk of lead contamination. Here, we develop a simple semi-quantitative method using cation exchange resins to evaluate the significance of lead-polyphosphate complexation. Applying this test in a range of waters, we reveal the dependency of lead-polyphosphate complexation on water hardness, polyphosphate dose, and the ratio of orthophosphate to polyphosphate. This approach can be used to predict the impact of a given polyphosphate product and dose on lead complexation, allowing utilities to predict the magnitude of the problem for a given water in about a day. We find a strong linear relationship between polyphosphate dose and complexed lead. Additionally, when >200 mg/L as CaCO3 of calcium is present, >3X less lead-polyphosphate complexation can occur versus when no calcium is present. Our work also demonstrates that testing artifacts probably caused past research to overestimate the danger of the lead complexation problem. This work has significant implications for public health and is timely as water lead contamination is increasingly scrutinized. The simple tests and corrosion control methods described herein can help drinking water utilities make informed water treatment decisions to reduce lead contamination and protect public health.","abstract_has_math":false,"creators":["Mazzola, Frank Anthony"],"institution":"Virginia Tech","degree_name":"Doctor of Philosophy","degree_level":"doctoral","degree_discipline":"Civil Engineering","degree_department":"Civil and Environmental Engineering","school":null,"contributors":[],"advisors":[],"committee_chairs":["Edwards, Marc A."],"committee_members":["Cai, Wenjun","Vikesland, Peter J.","Schreiber, Madeline E."],"year":2026,"date_issued":"2026-01-07","date_published":"2026-01-07","updated_at":"2026-07-22T22:18:50Z","subjects":["Lead contamination","drinking water","corrosion control","lead solder"],"languages":["en"],"rights":["Creative Commons Attribution 4.0 International"],"rights_urls":["http://creativecommons.org/licenses/by/4.0/"],"identifier_entries":[{"key":"dc:identifier.other","label":"Dc Identifier Other","values":["vt_gsexam:45535"],"render_values":[{"text":"vt_gsexam:45535","href":null,"code":true}]}]},"links":{"outbound_url":"https://hdl.handle.net/10919/140664","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.committeechair","label":"Committee Chair","values":["Edwards, Marc A."]},{"key":"dc:contributor.committeemember","label":"Committee Member","values":["Cai, Wenjun","Vikesland, Peter J.","Schreiber, Madeline E."]},{"key":"dc:contributor.department","label":"Department","values":["Civil and Environmental Engineering"]},{"key":"dc:creator","label":"Author","values":["Mazzola, Frank Anthony"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.accessioned","label":"Dc Date Accessioned","values":["2026-01-08T09:01:07Z"]},{"key":"dc:date.available","label":"Dc Date Available","values":["2026-01-08T09:01:07Z"]},{"key":"dc:date.issued","label":"Date","values":["2026-01-07"]},{"key":"dc:publisher","label":"Institution","values":["Virginia Tech"]},{"key":"dc:type","label":"Dc Type","values":["Dissertation"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Civil Engineering"]},{"key":"thesis:degree_level","label":"Degree Level","values":["doctoral"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Doctor of Philosophy"]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["Virginia Polytechnic Institute and State University"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Lead contamination","drinking water","corrosion control","lead solder"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language.iso","label":"Language (ISO)","values":["en"]},{"key":"dc:rights","label":"Dc Rights","values":["Creative Commons Attribution 4.0 International"]},{"key":"dc:rights.uri","label":"Rights URI","values":["http://creativecommons.org/licenses/by/4.0/"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.other","label":"Dc Identifier Other","values":["vt_gsexam:45535"]},{"key":"dc:identifier.uri","label":"Identifier URI","values":["https://hdl.handle.net/10919/140664"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["Recent high profile lead contamination events arising from lead solder corrosion have drawn attention to our alarmingly inadequate understanding of corrosion control chemistry. This dissertation provides novel contributions to an improved understanding of lead corrosion control in four sequential chapters that: 1) develop a new framework to proactively evaluate the impact of source water changes on lead solder corrosion, 2) demonstrate that in certain corrosive waters zinc orthophosphate can dramatically reduce lead contamination from solder at pHs around 7.5-9.5, but is ineffective in relatively non-corrosive waters or at pHs outside this range, 3) reveal that prolonged exposure to free chlorine can dramatically reduce lead contamination from solder by causing \"electrochemical reversal,\" protecting solder from galvanic corrosion, and 4) apply a method for measuring problematic lead complexation by polyphosphate, which reveals a significant health concern in some water chemistries but insignificant problems in others. Chapter 2 describes how water utilities are increasingly changing source waters in response to groundwater contamination, sustainability efforts, new regulations, and consolidation. We worked with three communities who unexpectedly experienced very severe lead contamination from lead-tin solder following a seemingly innocuous change in source water. We demonstrate how existing frameworks did not anticipate lead solder corrosion problems because: 1) prolonged exposure to non-corrosive water can preserve lead solder in relatively pristine condition, which is more susceptible to severe corrosion following changes in water chemistry, and 2) prolonged exposure to corrosive water can be self-limiting because all exposed lead in copper pipes could have corroded away within a period of decades, counter-intuitively producing low present day lead contamination in a highly corrosive water. A failure to understand the implications of these scenarios resulted in erroneous logic predicting that a source water change would be safe when it was not. We develop a proactive bench scale testing protocol and improved framework that can allow utilities to avoid similar mistakes in the future. Chapter 3 addresses divergent results regarding the effectiveness of zinc orthophosphate corrosion inhibitor in controlling lead solder corrosion; that is, some research reported remarkable advantages compared to adjusting pH/alkalinity or dosing orthophosphate alone, whereas other research found no benefits. We examined relative performance of zinc orthophosphate at a wide range of pHs (6.5, 7.5, 8.5, 9.5, 10.5) in a low alkalinity, low conductivity water with corrosivity increased by addition of extra chloride or nitrate, and demonstrate that the results depend on water chemistry. Specifically, zinc orthophosphate has little benefit in water with low chloride or nitrate, in which corrosivity is low, at any pH tested. But at higher corrosivity zinc orthophosphate significantly reduced lead release at pH 7.5-9.5, including 40X reductions in lead release at pH 8.5. Yet no relative advantage occurred at pH 6.5 and pH 10.5. Results are consistent with passivation from zinc phosphate precipitation from pH 7.5 to 9.5 as predicted by equilibrium modeling and supported by scale analysis. Similar methods can be used to predict relative performance of inhibitors for controlling lead solder corrosion in other source waters and determine if these results are generalizable. Chapter 4 explores a 40-year-old mystery with profound present-day implications. A study in Portland, Oregon had revealed that free chlorine had orders of magnitude less lead contamination when compared to chloramine, but the result was discounted because chlorine was always believed to be more corrosive than chloramine. Here, we resolve the controversy by demonstrating \"electrochemical reversal\" of the copper-solder galvanic couple in synthesized water similar to Portland's. That is, short-term exposure to chlorine did not reduce lead contamination, but prolonged exposure to free chlorine caused the normally anodic solder to become cathodic via formation of a Pb(IV) scale. This eventually caused free-chlorine treated water to have 10-100X less lead contamination than chloramine-treated water after several months of exposure. This discovery has major implications for water treatment and can also help explain why some waters dosed with free chlorine have anomalously low lead contamination. Chapter 5 examines fears that utilities adding polyphosphates to drinking water to sequester iron and manganese, or to prevent calcium carbonate scaling, will invariably suffer from higher lead solubility and a higher risk of lead contamination. Here, we develop a simple semi-quantitative method using cation exchange resins to evaluate the significance of lead-polyphosphate complexation. Applying this test in a range of waters, we reveal the dependency of lead-polyphosphate complexation on water hardness, polyphosphate dose, and the ratio of orthophosphate to polyphosphate. This approach can be used to predict the impact of a given polyphosphate product and dose on lead complexation, allowing utilities to predict the magnitude of the problem for a given water in about a day. We find a strong linear relationship between polyphosphate dose and complexed lead. Additionally, when >200 mg/L as CaCO3 of calcium is present, >3X less lead-polyphosphate complexation can occur versus when no calcium is present. Our work also demonstrates that testing artifacts probably caused past research to overestimate the danger of the lead complexation problem. This work has significant implications for public health and is timely as water lead contamination is increasingly scrutinized. The simple tests and corrosion control methods described herein can help drinking water utilities make informed water treatment decisions to reduce lead contamination and protect public health."]},{"key":"dc:description.abstractgeneral","label":"General Abstract","values":["Lead is a toxic metal that was commonly used in the drinking water pipes of homes and buildings constructed before 1986. Drinking water can become contaminated by corroding lead as it flows through pipes, threatening the health of consumers at the tap. Lead levels in drinking water have been increasingly scrutinized following severe contamination events in Washington, D.C. and Flint, Michigan. Lead contamination is always highly influenced by water chemistry; the same pipe materials can cause non-detectable lead levels in one community's water, but severe problems in another. Water utilities are increasingly changing their water sources due to groundwater contamination, concerns about sustainability, efforts to meet new regulations, and consolidation. We worked with several communities who have recently experienced severe lead contamination from lead solder in copper plumbing after changing source waters, and discovered cases in which severe contamination occurred when it was not predicted, and vice versa. To resolve existing erroneous logic and assumptions, we demonstrate that prolonged exposure to non-corrosive water can preserve lead solder in relatively pristine condition, which is highly susceptible to severe contamination following changes in water chemistry. Conversely, prolonged exposure to corrosive water can corrode all of the exposed lead in copper pipes within a period of decades, resulting in low lead contamination today. We develop a new framework and simple test to proactively assess the impact of source water changes on lead contamination from solder and avoid future problems. Water utilities commonly add chemicals such as orthophosphate to mitigate corrosion by forming protective pipe scales that do not readily dissolve or detach into water. Some utilities have observed profound reductions in lead release from solder in copper plumbing by dosing both zinc and orthophosphate (i.e., \"zinc orthophosphate\"), although this strategy has been ineffective in other cases. Here, we determine that the effectiveness of zinc orthophosphate depends heavily on the water's pH and corrosivity. Dosing zinc orthophosphate can result in remarkable benefits in corrosive waters from around pH 7.5-9.5, but in other cases it has no advantages whatsoever. Disinfectants such as free chlorine and chloramine are added to drinking water to kill harmful bacteria and viruses. Here, we determine that prolonged exposure to free chlorine can sometimes dramatically reduce lead contamination from solder compared to chloramine. While this is contrary to the conventional wisdom regarding higher corrosivity of chlorine, we show that in the long term, chlorine can actually protect lead solder from galvanic corrosion by forming a relatively insoluble and highly cathodic Pb(IV) corrosion scale on the solder surface. Many utilities dose polyphosphate chemicals to water in order limit aesthetic problems with iron and manganese, or to prevent calcium scaling in water heaters and pipes. But there is fear that polyphosphates increase lead solubility and contamination. Here, we present the first simple method to rapidly quantify the impact of polyphosphate on lead release. We then determine polyphosphate can cause problems with lead release in some water chemistries (e.g., soft waters), while minimal problems occur in other cases (e.g., hard waters). This test can be used by utilities to make informed decisions as to when and how, polyphosphate can be dosed without significantly increasing lead in water. This dissertation has important implications for avoiding public health problems with lead contamination. Water utilities are increasingly changing source waters and water treatment strategies, which can increase corrosivity, and low levels of lead once considered safe are now increasingly viewed with alarm. This work provides a range of tools and research results that can provide a basis for improved decision-making."]},{"key":"dc:description.degree","label":"Dc Description Degree","values":["Doctor of Philosophy"]},{"key":"dc:format.medium","label":"Dc Format Medium","values":["ETD"]},{"key":"dc:title","label":"Title","values":["Novel Insights into Lead Corrosion Control: Safely Changing Source Waters, Effective Use of Zinc Phosphate Inhibitors, Electrochemical Reversal of Solder, and Significance of Lead-Polyphosphate Complexation"]}]}],"canonical_facts":{"dc:contributor.committeechair":["Edwards, Marc A."],"dc:contributor.committeemember":["Cai, Wenjun","Vikesland, Peter J.","Schreiber, Madeline E."],"dc:contributor.department":["Civil and Environmental Engineering"],"dc:creator":["Mazzola, Frank Anthony"],"dc:date.accessioned":["2026-01-08T09:01:07Z"],"dc:date.available":["2026-01-08T09:01:07Z"],"dc:date.issued":["2026-01-07"],"dc:description.abstract":["Recent high profile lead contamination events arising from lead solder corrosion have drawn attention to our alarmingly inadequate understanding of corrosion control chemistry. This dissertation provides novel contributions to an improved understanding of lead corrosion control in four sequential chapters that: 1) develop a new framework to proactively evaluate the impact of source water changes on lead solder corrosion, 2) demonstrate that in certain corrosive waters zinc orthophosphate can dramatically reduce lead contamination from solder at pHs around 7.5-9.5, but is ineffective in relatively non-corrosive waters or at pHs outside this range, 3) reveal that prolonged exposure to free chlorine can dramatically reduce lead contamination from solder by causing \"electrochemical reversal,\" protecting solder from galvanic corrosion, and 4) apply a method for measuring problematic lead complexation by polyphosphate, which reveals a significant health concern in some water chemistries but insignificant problems in others. Chapter 2 describes how water utilities are increasingly changing source waters in response to groundwater contamination, sustainability efforts, new regulations, and consolidation. We worked with three communities who unexpectedly experienced very severe lead contamination from lead-tin solder following a seemingly innocuous change in source water. We demonstrate how existing frameworks did not anticipate lead solder corrosion problems because: 1) prolonged exposure to non-corrosive water can preserve lead solder in relatively pristine condition, which is more susceptible to severe corrosion following changes in water chemistry, and 2) prolonged exposure to corrosive water can be self-limiting because all exposed lead in copper pipes could have corroded away within a period of decades, counter-intuitively producing low present day lead contamination in a highly corrosive water. A failure to understand the implications of these scenarios resulted in erroneous logic predicting that a source water change would be safe when it was not. We develop a proactive bench scale testing protocol and improved framework that can allow utilities to avoid similar mistakes in the future. Chapter 3 addresses divergent results regarding the effectiveness of zinc orthophosphate corrosion inhibitor in controlling lead solder corrosion; that is, some research reported remarkable advantages compared to adjusting pH/alkalinity or dosing orthophosphate alone, whereas other research found no benefits. We examined relative performance of zinc orthophosphate at a wide range of pHs (6.5, 7.5, 8.5, 9.5, 10.5) in a low alkalinity, low conductivity water with corrosivity increased by addition of extra chloride or nitrate, and demonstrate that the results depend on water chemistry. Specifically, zinc orthophosphate has little benefit in water with low chloride or nitrate, in which corrosivity is low, at any pH tested. But at higher corrosivity zinc orthophosphate significantly reduced lead release at pH 7.5-9.5, including 40X reductions in lead release at pH 8.5. Yet no relative advantage occurred at pH 6.5 and pH 10.5. Results are consistent with passivation from zinc phosphate precipitation from pH 7.5 to 9.5 as predicted by equilibrium modeling and supported by scale analysis. Similar methods can be used to predict relative performance of inhibitors for controlling lead solder corrosion in other source waters and determine if these results are generalizable. Chapter 4 explores a 40-year-old mystery with profound present-day implications. A study in Portland, Oregon had revealed that free chlorine had orders of magnitude less lead contamination when compared to chloramine, but the result was discounted because chlorine was always believed to be more corrosive than chloramine. Here, we resolve the controversy by demonstrating \"electrochemical reversal\" of the copper-solder galvanic couple in synthesized water similar to Portland's. That is, short-term exposure to chlorine did not reduce lead contamination, but prolonged exposure to free chlorine caused the normally anodic solder to become cathodic via formation of a Pb(IV) scale. This eventually caused free-chlorine treated water to have 10-100X less lead contamination than chloramine-treated water after several months of exposure. This discovery has major implications for water treatment and can also help explain why some waters dosed with free chlorine have anomalously low lead contamination. Chapter 5 examines fears that utilities adding polyphosphates to drinking water to sequester iron and manganese, or to prevent calcium carbonate scaling, will invariably suffer from higher lead solubility and a higher risk of lead contamination. Here, we develop a simple semi-quantitative method using cation exchange resins to evaluate the significance of lead-polyphosphate complexation. Applying this test in a range of waters, we reveal the dependency of lead-polyphosphate complexation on water hardness, polyphosphate dose, and the ratio of orthophosphate to polyphosphate. This approach can be used to predict the impact of a given polyphosphate product and dose on lead complexation, allowing utilities to predict the magnitude of the problem for a given water in about a day. We find a strong linear relationship between polyphosphate dose and complexed lead. Additionally, when >200 mg/L as CaCO3 of calcium is present, >3X less lead-polyphosphate complexation can occur versus when no calcium is present. Our work also demonstrates that testing artifacts probably caused past research to overestimate the danger of the lead complexation problem. This work has significant implications for public health and is timely as water lead contamination is increasingly scrutinized. The simple tests and corrosion control methods described herein can help drinking water utilities make informed water treatment decisions to reduce lead contamination and protect public health."],"dc:description.abstractgeneral":["Lead is a toxic metal that was commonly used in the drinking water pipes of homes and buildings constructed before 1986. Drinking water can become contaminated by corroding lead as it flows through pipes, threatening the health of consumers at the tap. Lead levels in drinking water have been increasingly scrutinized following severe contamination events in Washington, D.C. and Flint, Michigan. Lead contamination is always highly influenced by water chemistry; the same pipe materials can cause non-detectable lead levels in one community's water, but severe problems in another. Water utilities are increasingly changing their water sources due to groundwater contamination, concerns about sustainability, efforts to meet new regulations, and consolidation. We worked with several communities who have recently experienced severe lead contamination from lead solder in copper plumbing after changing source waters, and discovered cases in which severe contamination occurred when it was not predicted, and vice versa. To resolve existing erroneous logic and assumptions, we demonstrate that prolonged exposure to non-corrosive water can preserve lead solder in relatively pristine condition, which is highly susceptible to severe contamination following changes in water chemistry. Conversely, prolonged exposure to corrosive water can corrode all of the exposed lead in copper pipes within a period of decades, resulting in low lead contamination today. We develop a new framework and simple test to proactively assess the impact of source water changes on lead contamination from solder and avoid future problems. Water utilities commonly add chemicals such as orthophosphate to mitigate corrosion by forming protective pipe scales that do not readily dissolve or detach into water. Some utilities have observed profound reductions in lead release from solder in copper plumbing by dosing both zinc and orthophosphate (i.e., \"zinc orthophosphate\"), although this strategy has been ineffective in other cases. Here, we determine that the effectiveness of zinc orthophosphate depends heavily on the water's pH and corrosivity. Dosing zinc orthophosphate can result in remarkable benefits in corrosive waters from around pH 7.5-9.5, but in other cases it has no advantages whatsoever. Disinfectants such as free chlorine and chloramine are added to drinking water to kill harmful bacteria and viruses. Here, we determine that prolonged exposure to free chlorine can sometimes dramatically reduce lead contamination from solder compared to chloramine. While this is contrary to the conventional wisdom regarding higher corrosivity of chlorine, we show that in the long term, chlorine can actually protect lead solder from galvanic corrosion by forming a relatively insoluble and highly cathodic Pb(IV) corrosion scale on the solder surface. Many utilities dose polyphosphate chemicals to water in order limit aesthetic problems with iron and manganese, or to prevent calcium scaling in water heaters and pipes. But there is fear that polyphosphates increase lead solubility and contamination. Here, we present the first simple method to rapidly quantify the impact of polyphosphate on lead release. We then determine polyphosphate can cause problems with lead release in some water chemistries (e.g., soft waters), while minimal problems occur in other cases (e.g., hard waters). This test can be used by utilities to make informed decisions as to when and how, polyphosphate can be dosed without significantly increasing lead in water. This dissertation has important implications for avoiding public health problems with lead contamination. Water utilities are increasingly changing source waters and water treatment strategies, which can increase corrosivity, and low levels of lead once considered safe are now increasingly viewed with alarm. This work provides a range of tools and research results that can provide a basis for improved decision-making."],"dc:description.degree":["Doctor of Philosophy"],"dc:format.medium":["ETD"],"dc:identifier.other":["vt_gsexam:45535"],"dc:identifier.uri":["https://hdl.handle.net/10919/140664"],"dc:language.iso":["en"],"dc:publisher":["Virginia Tech"],"dc:rights":["Creative Commons Attribution 4.0 International"],"dc:rights.uri":["http://creativecommons.org/licenses/by/4.0/"],"dc:subject":["Lead contamination","drinking water","corrosion control","lead solder"],"dc:title":["Novel Insights into Lead Corrosion Control: Safely Changing Source Waters, Effective Use of Zinc Phosphate Inhibitors, Electrochemical Reversal of Solder, and Significance of Lead-Polyphosphate Complexation"],"dc:type":["Dissertation"],"thesis:degree_discipline":["Civil Engineering"],"thesis:degree_level":["doctoral"],"thesis:degree_name":["Doctor of Philosophy"],"thesis:institution_name":["Virginia Polytechnic Institute and State University"]},"updated_at":"2026-07-22T22:18:50Z"}