Environmental Forensic Investigation of PFAS Occurrence, Drinking Water Monitoring, Public Water Systems, and Environmental Exposure Assessment
Project Overview
This environmental forensic investigation evaluated the occurrence, monitoring, and distribution of per- and polyfluoroalkyl substances (PFAS) within multiple public drinking water systems across the United States. The investigation integrated Consumer Confidence Reports (CCRs), historical drinking water quality records, statewide analytical datasets, public water system information, source water assessments, and treatment system documentation to evaluate PFAS occurrence, drinking water treatment practices, regulatory monitoring, and potential human exposure pathways. The objective of the investigation was to characterize PFAS detections across multiple water systems, evaluate differences between groundwater and surface water supplies, and develop a scientifically supported framework for assessing drinking water exposure and regulatory compliance.
A primary component of the investigation involved reviewing Consumer Confidence Reports prepared by public water utilities serving geographically diverse communities. These reports documented water sources, treatment processes, contaminant monitoring programs, regulatory compliance activities, and water quality results while providing system-specific information regarding PFAS monitoring and other emerging contaminants. Comparing multiple public water systems allowed the investigation to evaluate how differences in source water, treatment technologies, and regional hydrogeologic conditions may influence PFAS occurrence and drinking water quality.
The investigation further evaluated public water systems utilizing both groundwater and surface water supplies. Some systems obtained drinking water exclusively from deep groundwater aquifers, while others relied primarily on rivers, lakes, or purchased treated surface water. Because PFAS occurrence and transport may differ substantially between groundwater and surface water environments, evaluating multiple source water types provided a broader understanding of potential contaminant occurrence and treatment requirements across different drinking water systems.
Another major component of the investigation focused on historical drinking water monitoring information. Statewide analytical datasets spanning more than a decade of water quality sampling were compiled to evaluate temporal trends in PFAS monitoring, identify changes in analytical reporting over time, and assess the occurrence of PFAS among numerous public water systems. Integrating historical analytical results with utility-specific Consumer Confidence Reports provided a more comprehensive understanding of drinking water quality than either dataset could provide independently.
The investigation also examined source water vulnerability assessments prepared for individual public water systems. These assessments identified potential contamination sources surrounding drinking water supplies, including underground storage tanks, septic systems, industrial activities, agricultural operations, wastewater infrastructure, recreation areas, commercial facilities, and other land uses that may influence source water quality. Evaluating these potential contaminant sources provided important context for understanding how PFAS and other emerging contaminants may enter drinking water supplies prior to treatment.
An additional component of the investigation involved reviewing treatment technologies employed by individual water systems. The reviewed documents described conventional drinking water treatment processes, groundwater disinfection, corrosion control, fluoridation, filtration, ion exchange systems, and other treatment methods used to maintain drinking water quality. Understanding treatment processes is an important component of environmental forensic investigations because contaminant occurrence and potential human exposure depend upon both source water quality and treatment system performance.
Collectively, the reviewed materials supported a multidisciplinary environmental forensic investigation integrating drinking water chemistry, environmental data analysis, groundwater hydrogeology, surface water evaluation, regulatory compliance, exposure assessment, public water system operations, and contaminant fate and transport. By synthesizing historical analytical data, Consumer Confidence Reports, treatment information, and source water assessments, the investigation developed a scientifically supported framework for evaluating PFAS occurrence, drinking water quality, environmental exposure pathways, and emerging regulatory considerations associated with public water supplies.
Chemicals of Concern
The principal chemicals evaluated during this environmental forensic investigation were per- and polyfluoroalkyl substances (PFAS), a diverse class of synthetic fluorinated compounds widely used in industrial manufacturing, commercial products, and consumer goods because of their resistance to heat, water, oil, and chemical degradation. Particular emphasis was placed on evaluating PFAS occurrence within public drinking water systems, historical monitoring data, regulatory sampling programs, and source water assessments to better understand potential human exposure through drinking water. The investigation focused on PFAS occurrence across multiple public water systems rather than a single contaminated site, allowing for broader evaluation of contaminant distribution and drinking water quality trends.
A central component of the investigation involved evaluating PFAS detected through routine drinking water monitoring and the Unregulated Contaminant Monitoring Rule (UCMR) program. Consumer Confidence Reports documented continued monitoring for emerging contaminants, including PFAS compounds, while public water systems described the analytical programs used to identify contaminants that may not yet be subject to routine regulatory standards. Integrating these monitoring programs with historical analytical data provided a more comprehensive understanding of PFAS occurrence than reliance upon individual sampling events alone.
The investigation also evaluated groundwater and surface water as distinct environmental media through which PFAS may enter public drinking water supplies. Several water systems obtained drinking water from deep groundwater aquifers, while others relied primarily on rivers, lakes, reservoirs, or purchased treated surface water. Because PFAS transport mechanisms differ between groundwater and surface water environments, evaluating multiple source water types allowed the investigation to compare contaminant occurrence under varying hydrogeologic and watershed conditions.
Source water vulnerability represented another important aspect of the investigation. Source water assessments identified numerous land uses and environmental conditions that could potentially influence drinking water quality, including industrial facilities, underground storage tanks, wastewater infrastructure, septic systems, agricultural activities, recreational areas, commercial development, and transportation corridors. Although these assessments do not establish that PFAS contamination is present, they provide an important framework for identifying potential contaminant sources requiring additional investigation and monitoring.
Drinking water treatment systems were also evaluated because treatment processes directly influence contaminant removal prior to distribution. The reviewed materials described conventional surface water treatment, groundwater disinfection, filtration, corrosion control, ion exchange systems, chlorination, and other treatment technologies employed by individual utilities. Understanding treatment processes provides important context when interpreting PFAS monitoring data because contaminant occurrence within source water does not necessarily correspond to finished drinking water concentrations delivered to customers.
The investigation further recognized that PFAS represent a large family of chemically distinct compounds rather than a single contaminant. Although individual Consumer Confidence Reports primarily discussed PFAS monitoring from a regulatory perspective, historical analytical datasets included measurements for multiple PFAS compounds over time, allowing evaluation of contaminant occurrence across different water systems and monitoring periods. This broader perspective supports environmental forensic evaluations by identifying long-term trends that may not be apparent from a single reporting year.
An additional aspect of the investigation involved evaluating potential human exposure through public drinking water systems. Because public water supplies serve large populations over extended periods, even low concentrations of persistent contaminants may warrant continued monitoring as analytical methods improve and regulatory standards evolve. Consumer Confidence Reports emphasized ongoing monitoring, routine testing, and treatment optimization as important components of maintaining drinking water quality and protecting public health.
The investigation also considered the importance of evaluating historical analytical records rather than relying exclusively on current monitoring results. Statewide PFAS datasets spanning multiple years provide opportunities to identify changes in detection frequency, analytical reporting limits, monitoring priorities, and regulatory requirements over time. Integrating these historical datasets with Consumer Confidence Reports allows investigators to reconstruct long-term contaminant occurrence and evaluate how drinking water quality has evolved as analytical capabilities and regulatory oversight have advanced.
Collectively, the reviewed materials demonstrated that evaluating PFAS in public drinking water systems requires integration of environmental chemistry, hydrogeology, water treatment engineering, historical analytical datasets, regulatory monitoring programs, and source water protection. Considering these technical disciplines together provides a scientifically supported framework for understanding PFAS occurrence, drinking water quality, contaminant transport, and potential human exposure across diverse public water systems.
Methods
This environmental forensic investigation was conducted using accepted principles of environmental forensics, drinking water engineering, hydrogeology, environmental chemistry, exposure assessment, regulatory analysis, environmental data analytics, and public water system evaluation. Because the investigation encompassed multiple public water systems, historical monitoring records, and diverse water sources, a multidisciplinary weight-of-evidence methodology was used to integrate historical analytical datasets, Consumer Confidence Reports (CCRs), source water assessments, drinking water treatment information, and regulatory monitoring programs into a comprehensive technical evaluation.
A primary component of the investigation involved reviewing Consumer Confidence Reports prepared by public drinking water utilities. These reports were evaluated to characterize individual public water systems, identify drinking water sources, summarize treatment processes, document contaminant monitoring programs, and review reported analytical results. Because Consumer Confidence Reports are developed using standardized federal reporting requirements, they provide a consistent framework for comparing drinking water quality among geographically diverse communities while documenting compliance with applicable drinking water regulations.
The investigation also incorporated extensive review of historical PFAS monitoring data. Statewide analytical datasets spanning multiple years were compiled to evaluate temporal trends in PFAS occurrence, compare contaminant detections among public water systems, and assess changes in analytical reporting over time. Rather than evaluating individual sampling events independently, the investigation synthesized historical monitoring records to identify broader patterns in PFAS occurrence, regulatory monitoring, and drinking water quality across numerous utilities.
Source water characterization represented another important component of the investigation. Consumer Confidence Reports were reviewed to identify whether individual public water systems relied upon groundwater aquifers, rivers, lakes, reservoirs, or purchased treated water. Understanding source water characteristics is essential because contaminant occurrence, transport mechanisms, and treatment requirements may differ substantially between groundwater and surface water systems. Evaluating these differences allowed the investigation to compare potential PFAS occurrence under varying hydrogeologic and watershed conditions.
The investigation further evaluated source water vulnerability assessments prepared for individual public water systems. These assessments identified potential contaminant sources surrounding drinking water supplies, including industrial facilities, underground storage tanks, wastewater infrastructure, agricultural operations, septic systems, transportation corridors, commercial development, and recreational land uses. Reviewing these vulnerability assessments provided important context for understanding how PFAS and other contaminants may enter source waters before treatment and distribution.
An additional component of the investigation involved evaluating drinking water treatment technologies. Public water systems described treatment processes including conventional filtration, coagulation, sedimentation, disinfection, corrosion control, chlorination, ion exchange, and other technologies used to improve finished water quality. The investigation compared treatment approaches among utilities to better understand how engineering practices may influence contaminant removal, finished water quality, and regulatory compliance.
The investigation also incorporated review of federal drinking water monitoring programs, including the Unregulated Contaminant Monitoring Rule (UCMR). Consumer Confidence Reports documented utility participation in these monitoring programs and described the purpose of collecting occurrence data for emerging contaminants such as PFAS. Integrating regulatory monitoring information with historical analytical datasets provided additional insight into evolving drinking water standards, analytical capabilities, and contaminant surveillance efforts.
Another significant component of the investigation involved environmental data integration. Historical PFAS analytical records, Consumer Confidence Reports, treatment system information, source water assessments, and utility operational data were evaluated collectively rather than independently. This integrated approach allowed the investigation to identify relationships among contaminant occurrence, water source characteristics, treatment technologies, and potential exposure pathways while minimizing reliance upon any single dataset.
Finally, the investigation employed a multidisciplinary weight-of-evidence methodology integrating environmental chemistry, drinking water engineering, hydrogeology, regulatory science, environmental data analytics, exposure assessment, and environmental forensics. Information obtained from historical analytical datasets, Consumer Confidence Reports, source water assessments, treatment system documentation, and public water system records was evaluated according to its technical purpose and evidentiary value. Collectively, these independent lines of evidence provided a scientifically supported framework for evaluating PFAS occurrence, drinking water quality, contaminant transport, regulatory monitoring, and potential human exposure associated with public water supplies.
Results
Review of the available technical documentation demonstrated that evaluating PFAS in public drinking water systems requires integration of historical monitoring data, source water characterization, treatment system performance, regulatory compliance information, and environmental exposure assessment. Rather than focusing on a single public water system, the investigation synthesized information from multiple utilities located in different geographic regions to evaluate how PFAS occurrence may vary among groundwater and surface water supplies while identifying common monitoring and treatment practices used to protect public drinking water. Collectively, Consumer Confidence Reports, historical analytical datasets, and source water assessments provided multiple independent lines of evidence describing PFAS occurrence, drinking water quality, and emerging regulatory considerations.
One of the principal findings of the investigation was that public water systems utilize substantially different water sources and treatment strategies depending upon local hydrogeologic conditions. The reviewed utilities obtained drinking water from deep groundwater aquifers, major rivers, surface water reservoirs, and purchased treated surface water. These differences directly influence source water vulnerability, treatment requirements, contaminant occurrence, and long-term monitoring strategies. Evaluating multiple water supply systems demonstrated that PFAS investigations must account for differences in water source characteristics when interpreting analytical results and assessing potential environmental exposure pathways.
The investigation further demonstrated that source water vulnerability assessments provide valuable information for identifying potential contaminant sources before contaminants are detected in finished drinking water. The reviewed assessments identified numerous potential contributors to source water contamination, including industrial facilities, underground storage tanks, wastewater infrastructure, agricultural operations, septic systems, commercial development, recreational activities, and transportation-related land uses. Although these vulnerability assessments do not establish that contamination has occurred, they provide an important scientific framework for prioritizing monitoring efforts and developing proactive source water protection strategies.
Another significant finding involved the importance of advanced drinking water treatment technologies. The reviewed Consumer Confidence Reports described utilities employing a variety of treatment methods, including conventional filtration, chlorination, corrosion control, ion exchange systems, and other treatment processes designed to improve finished water quality. Some groundwater systems incorporated specialized treatment technologies to address naturally occurring or regulated constituents, illustrating how treatment approaches are tailored to local water quality conditions and contaminant concerns. Evaluating these engineering controls provides important context when interpreting PFAS monitoring data and assessing potential human exposure through drinking water.
The investigation also demonstrated the value of evaluating historical analytical datasets over extended periods rather than relying exclusively on a single year of monitoring results. Historical PFAS data spanning more than a decade allows investigators to evaluate long-term monitoring trends, identify changes in analytical methods and reporting limits, assess evolving regulatory priorities, and characterize contaminant occurrence through time. Integrating these historical datasets with annual Consumer Confidence Reports provides a more comprehensive understanding of drinking water quality than evaluating individual reporting periods independently.
Another important finding involved the role of routine regulatory monitoring in protecting public drinking water supplies. Consumer Confidence Reports consistently documented ongoing sampling programs, contaminant testing, regulatory compliance activities, and water quality evaluations performed throughout treatment and distribution systems. The reviewed utilities emphasized continuous monitoring of regulated contaminants while also participating in programs evaluating emerging contaminants such as PFAS. This layered monitoring approach provides multiple opportunities to identify changes in water quality before contaminants reach consumers.
The investigation further illustrated the importance of integrating engineering, chemistry, hydrogeology, and regulatory science when evaluating PFAS occurrence. Water quality data alone do not fully explain why contaminants may be present or absent within a particular system. Instead, contaminant occurrence reflects the interaction among source water characteristics, watershed conditions, groundwater hydrogeology, treatment system performance, distribution system operation, monitoring frequency, analytical capabilities, and regulatory requirements. Evaluating these disciplines together provides a more scientifically supported understanding of drinking water quality than considering analytical results in isolation.
Collectively, the investigation demonstrated that environmental forensic evaluations of PFAS in drinking water require integration of historical monitoring data, source water protection, treatment system engineering, environmental chemistry, hydrogeology, regulatory compliance, and exposure assessment. No single dataset independently characterized drinking water quality across the evaluated public water systems. However, when historical analytical records, Consumer Confidence Reports, source water assessments, treatment information, and regulatory monitoring programs were evaluated through a multidisciplinary weight-of-evidence methodology, they established a technically supported framework for evaluating PFAS occurrence, drinking water quality, public exposure pathways, and future monitoring priorities.
Conclusions
The reviewed technical documentation provides a comprehensive framework for evaluating PFAS occurrence in public drinking water systems using accepted principles of environmental forensics, drinking water engineering, hydrogeology, environmental chemistry, regulatory analysis, and exposure assessment. The investigation demonstrates that understanding PFAS in public water supplies requires more than evaluating individual analytical results. Instead, scientifically supported evaluations require integration of historical monitoring records, source water characteristics, treatment system performance, environmental conditions, and evolving regulatory requirements.
The investigation demonstrated that public drinking water systems utilize a wide variety of source waters, each possessing distinct hydrogeologic characteristics, contaminant vulnerabilities, and treatment requirements. Groundwater systems, surface water systems, and blended water supplies each present unique challenges for monitoring and managing emerging contaminants such as PFAS. Consequently, evaluating drinking water quality requires consideration of both the environmental setting surrounding a water source and the engineering processes used to produce finished drinking water.
The investigation further illustrates the importance of long-term environmental monitoring. Historical analytical datasets spanning multiple years provide substantially greater scientific value than isolated sampling events because they allow investigators to identify trends in contaminant occurrence, evaluate improvements in analytical methodologies, assess changing regulatory priorities, and better understand temporal variability in drinking water quality. Integrating long-term monitoring records with annual Consumer Confidence Reports provides a more comprehensive evaluation of drinking water systems than either source independently.
Review of the available source water assessments also demonstrates the value of proactive environmental protection. Identifying land uses and environmental conditions that may threaten drinking water supplies—including industrial activities, wastewater infrastructure, agricultural operations, underground storage tanks, septic systems, and commercial development—supports development of targeted monitoring strategies before contaminants affect finished drinking water. Environmental forensic investigations therefore provide an important tool for identifying potential exposure pathways and prioritizing future monitoring efforts.
The reviewed materials further demonstrate that drinking water treatment represents a critical component of exposure prevention. Utilities employ a combination of conventional treatment technologies, disinfection, filtration, corrosion control, ion exchange systems, and other engineered processes to improve water quality before distribution. Understanding treatment system design and operation is therefore essential when interpreting analytical results because contaminant occurrence in source water does not necessarily correspond to contaminant concentrations delivered to consumers. Evaluating treatment performance together with historical monitoring results provides a more scientifically defensible assessment of drinking water quality and potential human exposure.
More broadly, this investigation demonstrates how environmental consulting can integrate drinking water engineering, hydrogeology, environmental chemistry, regulatory science, environmental data analytics, exposure assessment, and environmental forensics into a comprehensive evaluation of public water systems. By combining historical analytical datasets, Consumer Confidence Reports, source water assessments, treatment system information, and regulatory monitoring records, these multidisciplinary investigations provide scientifically supported assessments of PFAS occurrence, contaminant transport, drinking water quality, public exposure pathways, and future monitoring priorities across complex public water supply systems.
This investigation was conducted under the direction of Dr. Paul Rosenfeld, an environmental scientist, environmental forensic expert, and environmental engineer with extensive experience evaluating drinking water contamination, groundwater quality, PFAS occurrence, environmental exposure pathways, contaminant fate and transport, public water systems, regulatory compliance, and complex environmental investigations. Throughout his career, Dr. Rosenfeld has investigated PFAS contamination, groundwater impacts, municipal drinking water systems, industrial releases, hazardous substances, chemical manufacturing facilities, Superfund sites, petroleum hydrocarbons, volatile organic compounds, metals, pesticides, and numerous other contaminants affecting environmental quality and public health. His work routinely integrates environmental chemistry, hydrogeology, engineering evaluation, regulatory analysis, exposure assessment, historical reconstruction, and technical document review to develop scientifically supported assessments of complex environmental and engineering issues.
References
California American Water. (2022). 2022 Consumer Confidence Report: Antelope Water System (PWS ID 3410031).
Illinois American Water. (2022). 2022 Consumer Confidence Report: Alpine Heights Water System (PWS ID IL1970030).
Iowa American Water. (2022). 2022 Consumer Confidence Report: Clinton District (PWS ID 2326048).
Tennessee American Water. (2022). 2022 Consumer Confidence Report: Citico Water Treatment Plant (PWS ID 0000107).
California State Water Resources Control Board. PFAS drinking water monitoring data (historical analytical datasets).
California American Water. Historical drinking water sampling records.
United States Environmental Protection Agency. Consumer Confidence Report (CCR) Rule.
United States Environmental Protection Agency. Unregulated Contaminant Monitoring Rule (UCMR).
United States Environmental Protection Agency. Safe Drinking Water Act.