Lead and copper in drinking water are known to pose aesthetic and health concerns for humans and pets. The United States Environmental Protection Agency (US EPA) Lead and Copper Rule (LCR) set 90th percentile action levels for lead (15 ppb) and copper (1.3 mg/L), above which utilities must implement systemwide corrosion control. However, gaps in the US EPA LCR leave at least 10% of residents using municipal water and all private well users vulnerable to elevated lead and copper in their drinking water. To help address these gaps in the LCR, this dissertation 1) Evaluates accuracy of at-home lead in water test kits to help residents identify lead problems, 2) Refines orthophosphate corrosion control guidance to help reduce cuprosolvency, 3) Identifies challenges to mitigating cuprosolvency by raising pH, and 4) Develops guidance that can help residents assess and address cuprosolvency problems.
Lead in drinking water can pose a variety of health concerns, particularly for young children. The revised LCR will still leave many residents unprotected from elevated lead in their drinking water and potentially wondering what to do about it. Many consumers concerned about lead may choose to purchase at-home lead in water test kits, but there is no certification authority to ensure their accuracy. Most off-the-shelf tests purchased in this work (12 of 16) were not able to detect dissolved or particulate lead at levels of concern in drinking water (i.e. near the lead action level of 15 ppb) due to high detection limits (5,000-20,000 ppb). Binary type tests, which indicate the presence or absence of lead based on a trigger threshold of 15 ppb, were often effective at detecting dissolved lead, but they failed to detect the presence of leaded particles that often cause high lead exposures in drinking water problems. Some of these problems detecting particles could be reduced using simple at-home acid dissolution with weak household acids such a vinegar or lemon juice. Our analysis points out the strengths and weaknesses of various types of at-home lead in water tests, which could be particularly important considering potential distrust in official results in the aftermath of the Flint Water Crisis.
Elevated cuprosolvency, or copper release into drinking water, can be an aesthetic concern due to fixture staining, blue water, and green hair and can pose health concerns for residents and pets. In addition to the general gaps in the LCR described above, compliance sampling in the LCR focuses on older homes at highest risk of elevated lead, rather than the newer homes at highest risk of elevated copper. Problems with elevated copper can sometimes go undetected as a result. Guidance was developed to help proactive utilities address cuprosolvency issues through the addition of orthophosphate corrosion inhibitors or pH adjustment as a function of a water's alkalinity. Linear regressions developed from pipe cuprosolvency tests (R2>0.98) determined a "minimum" orthophosphate dose or a "minimum" pH for a given alkalinity that was expected to almost always reduce copper below the 1.3 mg/L EPA action level in a reasonable length of time. The subjective nature of the terms "almost always" and "reasonable length of time" were quantitatively discussed based on laboratory and field data.
Orthophosphate addition was generally very effective at cuprosolvency control. Orthophosphate treatment in copper tube cuprosolvency tests produced cuprosolvency below the action level within the first week of treatment. As expected, orthophosphate treated waters sometimes resulted in higher long-term cuprosolvency than the same waters without orthophosphate corrosion control treatment. This is consistent with the formation of phosphate scales which have an intermediate solubility between the cupric hydroxide in new pipes and the malachite or tenorite scales expected in pipe aging without orthophosphate. A linear regression (R2>0.98) was used to determine the orthophosphate dose needed for a given alkalinity to yield copper below the 1.3 mg/L action level in the pipe segments with the highest, 2nd highest, 3rd highest copper concentrations (100th, 95th, or 90th percentile, n=20 replicates, five each from four manufacturers) after 4 or 22 weeks of pipe aging. This regression was generally in good agreement with a bin approach put forth in the 2015 Consensus Statement from the National Drinking Water Advisory Council, but in some cases the regression predicted that higher orthophosphate doses would be needed.
In contrast, due to the greater complexity of the reactions involved, a similar simplistic approach for pH adjustment is not widely applicable. A linear regression predicted that higher "minimum" pH values would be needed to control cuprosolvency compared to those suggested by the 2015 National Drinking Water Advisory Consensus Statement. Results indicate that factors such as the potential for calcite precipitation, pipe age, and significant variability in cuprosolvency from pipes of different manufacturers may warrant further research. Field LCR monitoring data indicated that 90th percentile copper concentrations continued to decline over a period of years or decades when orthophosphate is not used, and our laboratory results demonstrate a few cases where copper levels even increased with time. Consideration of confounding effects from other water quality parameters such as natural organic matter, silica, and sulfate would be necessary before the "minimum" pH criteria could be broadly applied.
Guidance was then developed to help address cuprosolvency issues on a single building or single home basis for residents with private wells or those with high copper in municipal systems meeting the LCR. A hierarchy of costs and considerations for various interventions are discussed including replumbing with alternative materials, using bottled water or point use pitcher, tap, or reverse osmosis filters to reduce copper consumption, and using whole house interventions like more conventional orthophosphate addition and pH adjustment, or unproven strategies like granular activated carbon filtration, reverse osmosis treatment, and ion exchange treatment. Laboratory and citizen science testing demonstrated that some inexpensive at-home tests for pH and copper, were accurate enough to serve as inputs for this guidance and could empower consumers to diagnose their problems and consider possible solutions. Citizen science field testing and companion laboratory studies of potential interventions indicate that short-term (<36 weeks) use of pH adjustment, granular activated carbon, anion exchange and reverse osmosis treated water were not effective at forming a protective scale for the resident's water tested. In this case-study, cuprosolvency problems were ultimately related to water chemistry and linked to variability in influent water pH.
Overall, this work highlighted weaknesses in the current US EPA Lead and Copper Rule. It attempted to close some of these gaps by assessing the accuracy of at-home citizen science tests for lead and copper detection and developing guidance to support voluntary interventions by utilities or consumers. Ideally, local authorities (utilities, health departments, cooperative extension programs) could adapt this guidance to account for local water quality considerations and support consumers in resolving cuprosolvency issues. This guidance may also serve as a citizen science approach that some consumers could use to make decisions on their own. Future work could extend and improve on these initial efforts. / Doctor of Philosophy / Lead or copper in drinking water can come from corrosion of plumbing materials. Elevated levels of these metals can cause aesthetic concerns like blue water and fixture staining, as well as health concerns for humans and pets. The United States Environmental Protection Agency (US EPA) Lead and Copper Rule (LCR) is designed to address system wide lead and copper corrosion problems in municipal water supplies. According to the LCR, utilities must notify consumers and implement corrosion control if more than 10% of homes sampled have lead above 15 ppb or copper above 1.3 mg/L. However, gaps in the US EPA LCR leave at least 10% of residents using municipal water and all private well users vulnerable to elevated lead and copper in their drinking water. To help address these gaps in the LCR, this dissertation 1) Evaluates how accurate residential at-home tests are at detecting lead in water, 2) Refines orthophosphate corrosion control guidance to help address elevated cuprosolvency (i.e. copper release to water), 3) Identifies challenges addressing cuprosolvency issues by raising the pH, and 4) Develops guidance to help residents detect and address cuprosolvency problems.
Lead in drinking water can come from corrosion of lead bearing plumbing such as lead service lines and lead solder. Lead can pose a variety of health concerns, particularly for young children. In spite of recent revisions, the LCR will still leave many residents unprotected from elevated lead in their drinking water and potentially wondering what to do about it. Many consumers concerned about lead may choose to purchase at-home lead in water test kits, but there is no certification authority to ensure that they are accurate. Most off- the-shelf tests purchased in this work (12 of 16) were not able to detect dissolved lead or lead from particulate at concentrations expected to occur in drinking water due to high detection limits (5,000-20,000 ppb). Binary type tests, which indicate the presence or absence of lead based on a trigger threshold of 15 ppb, were often effective at detecting dissolved lead, but they failed to detect the presence of leaded particles that often cause high lead exposures in drinking water problems. Some of these problems detecting particles could be reduced using a simple procedure to attempt to dissolve the particles using weak household acids like vine- gar or lemon juice. Our analysis points out the strengths and weaknesses of various types of at-home lead in water tests, which could be particularly important considering potential distrust in official results in the aftermath of the Flint Water Crisis.
Elevated cuprosolvency, or copper release into drinking water, primarily causes aesthetic problems like fixture staining and blue water, and it can also pose acute and serious health concerns for residents and some pets. Many of the same issues with the LCR that leave residents at risk of lead can also lead to unaddressed issues with elevated copper. In addition to those issues, the LCR focuses on collecting water samples in older homes at highest risk of lead, instead of newer homes at highest risk of copper. This means that many cuprosolvency problems could go undetected. Guidance was developed to help proactive utilities address cuprosolvency problems throughout the whole water system by adding orthophosphate corrosion inhibitors or adjusting the pH of their water. Linear relationships were developed from cuprosolvency testing in copper pipes (strong correlations, R2>0.98) to determine the "minimum" orthophosphate dose or pH value needed based on the water alkalinity that was expected to almost always reduce copper below the 1.3 mg/L EPA action level in a reason- able length of time. We also discuss the subjective nature of the terms "almost always" and "reasonable length of time" based on laboratory and field data.
Adding orthophosphate was generally very effective at controlling cuprosolvency. In tests in copper pipe segments, copper concentrations in the water were below the action level within one week of starting to add orthophosphate. As expected, sometimes waters with orthophosphate treatment resulted in higher long-term copper concentrations than waters without orthophosphate. This is in agreement with reports of formation of phosphate mineral scales which have an intermediate solubility between those in new pipes and the scales expected in pipe aging without orthophosphate. A linear regression (strong correlation, R2>0.98) was used to determine the orthophosphate dose needed for a given alkalinity to yield copper below the 1.3 mg/L action level in the worst, second worst, and third worst pipes of the 20 pipe segments tested (100th, 95th, or 90th percentile) after 4 or 22 weeks of pipe aging. This linear relationship was generally in good agreement with a bin approach put forth in the 2015 Consensus Statement from the National Drinking Water Advisory Council, but in some cases the regression predicted that higher orthophosphate doses would be needed.
In contrast, we showed that adjusting the pH to control cuprosolvency was too simplistic to be widely applicable because the chemical reactions involved are more complex. The linear relationship we developed predicted that higher "minimum" pH values would be needed to control cuprosolvency compared to those suggested by the 2015 National Drinking Water Advisory Consensus Statement. Other factors such as the potential calcite precipitation, which can clog pipes, pipe age, and significant variability in copper coming off pipes from different manufacturers may require consideration when considering treatment options. LCR monitoring data from utilities indicated that copper concentrations continued to decline over a period of years or decades when orthophosphate was not used, and our laboratory results demonstrate a few cases where copper levels even increased with time. We also showed that other water quality components like natural organic matter, silica, and sulfate can affect cuprosolvency and could make it difficult to broadly apply the "minimum" pH approach for controlling cuprosolvency in places with different water qualities.
Guidance was then developed to help address cuprosolvency issues on a single building or single home basis for residents with private wells or those with high copper in municipal systems meeting the LCR. A hierarchy of costs and considerations is described for various interventions including replumbing with alternative materials, using bottled water or point use pitcher, tap, or reverse osmosis filters to reduce copper consumption, and using whole house interventions like more conventional orthophosphate addition and pH adjustment, or unproven strategies like granular activated carbon filtration, reverse osmosis treatment, and ion exchange treatment. Laboratory and citizen science testing demonstrated that some in- expensive at-home tests for pH and copper, were accurate enough to serve as inputs for this guidance and could empower consumers to diagnose their problems and consider possible solutions. Testing of potential water treatments in the laboratory and citizen science testing in a resident's home showed that short-term (<36 weeks) use of pH adjustment, granular activated carbon, anion exchange, and reverse osmosis treated water did not form a permanent, low-solubility protective scale for this resident's water. In this case-study, cuprosolvency problems were ultimately related to water chemistry and linked to variability in incoming pH of the water.
This thesis highlighted weaknesses in the current US EPA Lead and Copper Rule. It at- tempted to address some of these issues by determining the accuracy of at-home citizen science tests to help residents detect lead and copper and developing guidance to support voluntary interventions by utilities or consumers. Ideally, local authorities (utilities, health departments, cooperative extension programs) could adapt this guidance to account for local water quality considerations and support consumers in resolving cuprosolvency issues. This guidance may also serve as a citizen science approach that some consumers could use to make decisions on their own. Future work could extend and improve on these initial efforts.
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/115479 |
| Date | 21 June 2023 |
| Creators | Kriss, Rebecca Boyce |
| Contributors | Civil and Environmental Engineering, Edwards, Marc A., Katner, Adrienne Lee, Vikesland, Peter J., Pieper, Kelsey Janette, Benham, Brian L. |
| Publisher | Virginia Tech |
| Source Sets | Virginia Tech Theses and Dissertation |
| Language | English |
| Detected Language | English |
| Type | Dissertation |
| Format | ETD, application/pdf |
| Rights | Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International, http://creativecommons.org/licenses/by-nc-nd/4.0/ |
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