Drinking water in the United States rarely is tested for contaminants and pathogens at the tap, where human exposure can occur. In this special issue, we present the science to help understand contaminants and pathogens in drinking water at business and residential taps.
Protection of the Nation's drinking water resources is a priority for and the responsibility of the U.S. Environmental Protection Agency (EPA) under the Safe Drinking Water Act in conjunction with State and Tribal agencies and water utilities. The majority of (approximately 282 million) Americans are served by public drinking water treatment systems that monitor treated water for approximately 100 regulated contaminants prior to distribution as part of compliance monitoring required by the Safe Drinking Water Act. In addition, the Unregulated Contaminant Monitoring Rule requires monitoring of as many as 30 other contaminants every 5 years. Public water supply treatment, followed by compliance monitoring, form a cornerstone to maintaining safe public drinking water in the United States.
Water chemistry can change, however, from the point of distribution at a drinking water facility to the taps in homes and businesses owing to leaks, cross-connections, onsite plumbing, and back-siphonage. Moreover, very few chemicals (with the exception of disinfection byproducts, disinfectant residuals, lead, and copper) are monitored at the tap in homes or businesses and novel pathogens continue to emerge.
This lack of monitoring leaves gaps in understanding if tap water contains contaminants or pathogens that might be a hazard now or in the future, and gaps in understanding human exposure through water from residential or business taps.
In addition, as many as 60 million Americans living in rural areas supply their own drinking water from onsite wells. Unlike publicly supplied water, these wells are not federally regulated, and treatment is entirely the responsibility of the homeowner. Consequently, these rural homeowners often know very little about the quality of their drinking water.
This leaves questions related to contaminants and pathogens present in drinking water consumed at the point of exposure including the following:
- What contaminants or pathogens are present in tap waters that come from publicly or privately supplied drinking water sources?
- What factors affect the types and concentrations of contaminants and pathogens present in tap water?
- Can predictive tools help us to define, prioritize, and mitigate human exposure and health risks?
U.S. Geological Survey Provides Answers
The U.S. Geological Survey (USGS) has long filled gaps and built a foundation of research on chemical mixtures detected in surface water and groundwater resources serving as source waters for drinking water, and research on chemical mixtures detected in public drinking water supplies prior to distribution to residences and businesses.
The USGS studies the interconnected continuum of water from it sources in watersheds through natural and built environments to the point of use at the tap. During 2016, the USGS and collaborators conducted pilot studies at business and residential taps across the Nation. Then in a 2017 follow-up study in the Greater Chicago Area, water samples were collected from the taps of 45 Chicago-area residences. The studies revealed that chemicals not commonly monitored were present in tap water samples. Consistent with previous findings in tap waters, disinfection byproducts (DBPs), low-level concentrations of per- and polyfluoroalkyl substances (PFASs), and pesticides were frequently detected. Very few of the more than 500 chemicals measured exceeded regulatory guidelines. Although no enforceable guidelines were exceeded, drinking water goals used to manage public drinking water supplies for arsenic, lead, uranium, and two DBPs (bromodichloromethane and tribromomethane) were exceeded. The results of these initial pilot studies emphasized the high quality and effective treatment of the public drinking water in the areas sampled. The results also demonstrated the potential for human exposure to low concentrations of chemicals in mixtures that are not commonly monitored or assessed at the point of exposure. The occurrence of these chemicals does not necessarily indicate adverse effects because currently there is a gap in the understanding of whether exposure to these chemical mixtures affect human health.
Research supported by the USGS Environmental Health Program continues to foster collaborations with public health experts outside the USGS (such as National Institute of Environmental Health Sciences, Centers for Disease Control and Prevention, EPA, Public Health Departments, and academics) to help them fill these gaps by exploring linkages between contaminant exposures in tap water and health outcomes. These collaborations bring efficiency by combining USGS expertise in transport, fate, and analysis of contaminants with the public health expertise in human health outcomes.
The USGS is delivering science, data, and related information needed for decision makers who maintain the safety of U.S. drinking water supplies and for rural homeowners with private wells, those using public water supplies in urban areas, and those on tribal lands. This research helps us to understand the contaminants and pathogens in tap water and how increased reuse of wastewaters in watersheds and aquifers, aging drinking water infrastructure, legacy plumbing materials, and disinfection processes may affect contaminant exposures from drinking water.
Read this collection of featured science articles to discover more about contaminants in drinking water and the research of the USGS Water and Wastewater Infrastructure Team in the Environmental Health Program (Toxic Substances Hydrology and Contaminant Biology) of the Ecosystems Mission Area.
Below are other science projects associated with this project.
Mixtures of Organic and Inorganic Chemicals Characterized in Water from the Taps of Residences in the Greater Chicago Area— Science to Understand Contaminant Exposures in Drinking Water
Drinking Water and Source Water Research
Arsenic and Drinking Water
What is the Chemical and Microbial Content of Our Tap Waters?
Exploring the Suitability of a Modeling Approach to Estimate Contaminant Occurrence in Drinking Water Sources
Study Highlights the Complexity of Chemical Mixtures in United States Streams
Understanding Chemical and Microbial Contaminants in Public Drinking Water
Below are data associated with this project.
Occurrence and Concentrations of Trace Elements in Discrete Tapwater Samples Collected in Chicago, Illinois and East Chicago, Indiana, 2017
Target-Chemical Concentrations, Exposure Activity Ratios, and Bioassay Results for Assessment of Mixed-Organic/Inorganic-Chemical Exposure in USA Tapwater, 2016
Below are publications associated with this project.
Reconnaissance of mixed organic and inorganic chemicals in private and public supply tapwaters at selected residential and workplace sites in the United States
Safe drinking water at the point-of-use (tapwater, TW) is a United States public health priority. Multiple lines of evidence were used to evaluate potential human health concerns of 482 organics and 19 inorganics in TW from 13 (7 public supply, 6 private well self-supply) home and 12 (public supply) workplace locations in 11 states. Only uranium (61.9 μg L–1, private well) exceeded a National Prim
Methods used for the collection and analysis of chemical and biological data for the Tapwater Exposure Study, United States, 2016–17
Concentrations of lead and other inorganic constituents in samples of raw intake and treated drinking water from the municipal water filtration plant and residential tapwater in Chicago, Illinois, and East Chicago, Indiana, July–December 2017
Nationwide reconnaissance of contaminants of emerging concern in source and treated drinking waters of the United States
Aquatic concentrations of chemical analytes compared to ecotoxicity estimates
Comparison of in vitro estrogenic activity and estrogen concentrations insource and treated waters from 25 U.S. drinking water treatment plants
Nationwide reconnaissance of contaminants of emerging concern in source and treated drinking waters of the United States: Pharmaceuticals
The importance of quality control in validating concentrationsof contaminants of emerging concern in source and treateddrinking water samples
Human health screening and public health significance of contaminants of emerging concern detected in public water supplies
Microbial pathogens in source and treated waters from drinking water treatment plants in the United States and implications for human health
- Overview
Drinking water in the United States rarely is tested for contaminants and pathogens at the tap, where human exposure can occur. In this special issue, we present the science to help understand contaminants and pathogens in drinking water at business and residential taps.
Protection of the Nation's drinking water resources is a priority for and the responsibility of the U.S. Environmental Protection Agency (EPA) under the Safe Drinking Water Act in conjunction with State and Tribal agencies and water utilities. The majority of (approximately 282 million) Americans are served by public drinking water treatment systems that monitor treated water for approximately 100 regulated contaminants prior to distribution as part of compliance monitoring required by the Safe Drinking Water Act. In addition, the Unregulated Contaminant Monitoring Rule requires monitoring of as many as 30 other contaminants every 5 years. Public water supply treatment, followed by compliance monitoring, form a cornerstone to maintaining safe public drinking water in the United States.
Many rural residents get their water from private wells where treatment is the responsibility of the homeowner. (Credit: Victoria Christensen, USGS Upper Midwest Water Science Center. Public domain.) Water chemistry can change, however, from the point of distribution at a drinking water facility to the taps in homes and businesses owing to leaks, cross-connections, onsite plumbing, and back-siphonage. Moreover, very few chemicals (with the exception of disinfection byproducts, disinfectant residuals, lead, and copper) are monitored at the tap in homes or businesses and novel pathogens continue to emerge.
This lack of monitoring leaves gaps in understanding if tap water contains contaminants or pathogens that might be a hazard now or in the future, and gaps in understanding human exposure through water from residential or business taps.
In addition, as many as 60 million Americans living in rural areas supply their own drinking water from onsite wells. Unlike publicly supplied water, these wells are not federally regulated, and treatment is entirely the responsibility of the homeowner. Consequently, these rural homeowners often know very little about the quality of their drinking water.
This leaves questions related to contaminants and pathogens present in drinking water consumed at the point of exposure including the following:
- What contaminants or pathogens are present in tap waters that come from publicly or privately supplied drinking water sources?
- What factors affect the types and concentrations of contaminants and pathogens present in tap water?
- Can predictive tools help us to define, prioritize, and mitigate human exposure and health risks?
U.S. Geological Survey Provides Answers
The U.S. Geological Survey (USGS) has long filled gaps and built a foundation of research on chemical mixtures detected in surface water and groundwater resources serving as source waters for drinking water, and research on chemical mixtures detected in public drinking water supplies prior to distribution to residences and businesses.
The U.S. Geological Survey is doing the research necessary to understand contaminants and pathogens in tap water at businesses and residences to help other agencies ensure this safe drinking water supply. (Credit: David W. Morganwalp, US Geological Survey. Public domain.) The USGS studies the interconnected continuum of water from it sources in watersheds through natural and built environments to the point of use at the tap. During 2016, the USGS and collaborators conducted pilot studies at business and residential taps across the Nation. Then in a 2017 follow-up study in the Greater Chicago Area, water samples were collected from the taps of 45 Chicago-area residences. The studies revealed that chemicals not commonly monitored were present in tap water samples. Consistent with previous findings in tap waters, disinfection byproducts (DBPs), low-level concentrations of per- and polyfluoroalkyl substances (PFASs), and pesticides were frequently detected. Very few of the more than 500 chemicals measured exceeded regulatory guidelines. Although no enforceable guidelines were exceeded, drinking water goals used to manage public drinking water supplies for arsenic, lead, uranium, and two DBPs (bromodichloromethane and tribromomethane) were exceeded. The results of these initial pilot studies emphasized the high quality and effective treatment of the public drinking water in the areas sampled. The results also demonstrated the potential for human exposure to low concentrations of chemicals in mixtures that are not commonly monitored or assessed at the point of exposure. The occurrence of these chemicals does not necessarily indicate adverse effects because currently there is a gap in the understanding of whether exposure to these chemical mixtures affect human health.
Research supported by the USGS Environmental Health Program continues to foster collaborations with public health experts outside the USGS (such as National Institute of Environmental Health Sciences, Centers for Disease Control and Prevention, EPA, Public Health Departments, and academics) to help them fill these gaps by exploring linkages between contaminant exposures in tap water and health outcomes. These collaborations bring efficiency by combining USGS expertise in transport, fate, and analysis of contaminants with the public health expertise in human health outcomes.
The USGS is delivering science, data, and related information needed for decision makers who maintain the safety of U.S. drinking water supplies and for rural homeowners with private wells, those using public water supplies in urban areas, and those on tribal lands. This research helps us to understand the contaminants and pathogens in tap water and how increased reuse of wastewaters in watersheds and aquifers, aging drinking water infrastructure, legacy plumbing materials, and disinfection processes may affect contaminant exposures from drinking water.
Read this collection of featured science articles to discover more about contaminants in drinking water and the research of the USGS Water and Wastewater Infrastructure Team in the Environmental Health Program (Toxic Substances Hydrology and Contaminant Biology) of the Ecosystems Mission Area.
- Science
Below are other science projects associated with this project.
Mixtures of Organic and Inorganic Chemicals Characterized in Water from the Taps of Residences in the Greater Chicago Area— Science to Understand Contaminant Exposures in Drinking Water
As a component of ongoing research with a coalition of partners, including the U.S. Geological Survey U.S. Environmental Protection Agency, National Institute of Environmental Health Sciences, Colorado School of Mines, University of Illinois Chicago, and University of South Carolina, water was collected from the taps of 45 Chicago-area residences and analyzed for 540 organic and 35 inorganic...Drinking Water and Source Water Research
Reliable drinking water is vital for the health and safety of all Americans. The USGS monitors and assesses the quality of the water used as a source for our nation's drinking water needs.Arsenic and Drinking Water
Arsenic is a naturally occurring element, but long-term exposure can cause cancer in people. There has been a substantial amount of research done to address arsenic in groundwater and drinking-water supplies around the country. The USGS studies local and national sources of arsenic to help health officials better manage our water resources.What is the Chemical and Microbial Content of Our Tap Waters?
Safe Drinking Water Act compliance addresses the safety of public-supply water systems. The composition of public-supply drinking water is generally only tested at the treatment facility, and not at the tap in homes and businesses after traveling through the water distribution system. Only lead and copper are tested at a subset of residential and other taps.Testing of water in private wells is...Exploring the Suitability of a Modeling Approach to Estimate Contaminant Occurrence in Drinking Water Sources
Scientists explored the suitability of the DeFacto Reuse in our Nation's Consumable Supply (DRINCS) model to estimate the likelihood of contaminants from upstream wastewater discharges to enter drinking water facility intakes.Study Highlights the Complexity of Chemical Mixtures in United States Streams
A new study highlights the complexity of chemical mixtures in streams and advances the understanding of wildlife and human exposure to complex chemical mixtures.Understanding Chemical and Microbial Contaminants in Public Drinking Water
Collaborative joint agency study provides nationally consistent and rigorously quality-assured datasets on a wide range of chemical and microbial contaminants present in source and treated public drinking water supplies. Tap water was not analyzed in this study. - Data
Below are data associated with this project.
Occurrence and Concentrations of Trace Elements in Discrete Tapwater Samples Collected in Chicago, Illinois and East Chicago, Indiana, 2017
This dataset contains the trace element concentration results for samples collected from tapwater sites in East Chicago, Indiana, August-September, 2017, and Chicago, Illinois, July-December, 2017. Samples were collected one time, from 45 private residences and associated drinking water plants and source water locations. Water-quality samples were analyzed at two U.S. Geological Survey laboratorieTarget-Chemical Concentrations, Exposure Activity Ratios, and Bioassay Results for Assessment of Mixed-Organic/Inorganic-Chemical Exposure in USA Tapwater, 2016
Chemical and biological concentration results, quality assurance and quality control and statistical summaries from 26 tapwater samples, collected from paired residential and work place sites in 11 states in 2016. Samples were analylzed at U.S. Geological Survey and U.S. Environmental Protection Agency laboratories. - Publications
Below are publications associated with this project.
Reconnaissance of mixed organic and inorganic chemicals in private and public supply tapwaters at selected residential and workplace sites in the United States
Safe drinking water at the point-of-use (tapwater, TW) is a United States public health priority. Multiple lines of evidence were used to evaluate potential human health concerns of 482 organics and 19 inorganics in TW from 13 (7 public supply, 6 private well self-supply) home and 12 (public supply) workplace locations in 11 states. Only uranium (61.9 μg L–1, private well) exceeded a National Prim
AuthorsPaul M. Bradley, Dana W. Kolpin, Kristin M. Romanok, Kelly L. Smalling, Michael J. Focazio, Juliane B. Brown, Mary C. Cardon, Kurt D. Carpenter, Steven R. Corsi, Laura A. DeCicco, Julie E. Dietze, Nicola Evans, Edward T. Furlong, Carrie E. Givens, James L. Gray, Dale W. Griffin, Christopher P. Higgins, Michelle L. Hladik, Luke R. Iwanowicz, Celeste A. Journey, Kathryn Kuivila, Jason R. Masoner, Carrie A. McDonough, Michael T. Meyer, James L. Orlando, Mark J. Strynar, Christopher P. Weis, Vickie S. WilsonByEcosystems Mission Area, Water Resources Mission Area, Contaminant Biology, Environmental Health Program, Toxic Substances Hydrology, California Water Science Center, Central Midwest Water Science Center, Colorado Water Science Center, Eastern Ecological Science Center, Kansas Water Science Center, New Jersey Water Science Center, Oregon Water Science Center, South Atlantic Water Science Center (SAWSC), St. Petersburg Coastal and Marine Science Center, Upper Midwest Environmental Sciences Center, Upper Midwest Water Science Center, National Water Quality LaboratoryMethods used for the collection and analysis of chemical and biological data for the Tapwater Exposure Study, United States, 2016–17
In 2016, the U.S. Geological Survey (USGS) Environmental Health Mission Area, initiated the Tapwater Exposure Study as part of an infrastructure project to assess human exposure to potential threats from complex mixtures of contaminants. In the pilot phase (2016), samples were collected from 11 States throughout the United States, and in the second phase (2017), the study focused on the Greater ChAuthorsKristin M. Romanok, Dana W. Kolpin, Shannon M. Meppelink, Maria Argos, Juliane B. Brown, Michael J. Devito, Julie E. Dietze, Carrie E. Givens, James L. Gray, Christopher P. Higgins, Michelle L. Hladik, Luke R. Iwanowicz, Keith A. Loftin, R. Blaine McCleskey, Carrie A. McDonough, Michael T. Meyer, Mark J. Strynar, Christopher P. Weis, Vickie S. Wilson, Paul M. BradleyConcentrations of lead and other inorganic constituents in samples of raw intake and treated drinking water from the municipal water filtration plant and residential tapwater in Chicago, Illinois, and East Chicago, Indiana, July–December 2017
The U.S. Geological Survey (USGS) Environmental Health Mission Area (EHMA) is providing comprehensive science on sources, movement, and transformation of contaminants and pathogens in watershed and aquifer drinking-water supplies and in built water and wastewater infrastructure (referred to as the USGS Water and Wastewater Infrastructure project) in the Greater Chicago Area and elsewhere in the UnAuthorsKristin M. Romanok, Dana W. Kolpin, Shannon M. Meppelink, Michael J. Focazio, Maria Argos, Mary E. Hollingsworth, R. Blaine McCleskey, Andrea R. Putz, Alan Stark, Christopher P. Weis, Abderrahman Zehraoui, Paul M. BradleyNationwide reconnaissance of contaminants of emerging concern in source and treated drinking waters of the United States
When chemical or microbial contaminants are assessed for potential effect or possible regulation in ambient and drinking waters, a critical first step is determining if the contaminants occur and if they are at concentrations that may cause human or ecological health concerns. To this end, source and treated drinking water samples from 29 drinking water treatment plants (DWTPs) were analyzed as paAuthorsSusan T. Glassmeyer, Edward T. Furlong, Dana W. Kolpin, Angela L. Batt, Robert Benson, J. Scott Boone, Octavia D. Conerly, Maura J. Donohue, Dawn N. King, Mitchell S. Kostich, Heath E. Mash, Stacy Pfaller, Kathleen M. Schenck, Jane Ellen Simmons, Eunice A. Varughese, Stephen J. Vesper, Eric N. Villegas, Vickie S. WilsonAquatic concentrations of chemical analytes compared to ecotoxicity estimates
We describe screening level estimates of potential aquatic toxicity posed by 227 chemical analytes that were measured in 25 ambient water samples collected as part of a joint USGS/USEPA drinking water plant study. Measured concentrations were compared to biological effect concentration (EC) estimates, including USEPA aquatic life criteria, effective plasma concentrations of pharmaceuticals, publisAuthorsMitchell S. Kostich, Robert W. Flick, Angela L. Batt, Heath E. Mash, J. Scott Boone, Edward T. Furlong, Dana W. Kolpin, Susan T. GlassmeyerComparison of in vitro estrogenic activity and estrogen concentrations insource and treated waters from 25 U.S. drinking water treatment plants
In vitro bioassays have been successfully used to screen for estrogenic activity in wastewater and surface water, however, few have been applied to treated drinking water. Here, extracts of source and treated water samples were assayed for estrogenic activity using T47D-KBluc cells and analyzed by liquid chromatography-Fourier transform mass spectrometry (LC-FTMS) for natural and synthetic estrogeAuthorsJustin M. Conley, Nicola Evans, Heath Mash, Laura Rosenblum, Kathleen Schenck, Susan Glassmeyer, Edward T. Furlong, Dana W. Kolpin, Vickie S. WilsonNationwide reconnaissance of contaminants of emerging concern in source and treated drinking waters of the United States: Pharmaceuticals
Mobile and persistent chemicals that are present in urban wastewater, such as pharmaceuticals, may survive on-site ormunicipal wastewater treatment and post-discharge environmental processes. These pharmaceuticals have the potential to reach surface and groundwaters, essential drinking-water sources. A joint, two-phase U.S. Geological Survey-U.S. Environmental Protection Agency study examined sourAuthorsEdward T. Furlong, Angela L. Batt, Susan T. Glassmeyer, Mary C. Noriega, Dana W. Kolpin, Heath Mash, Kathleen M. SchenckThe importance of quality control in validating concentrationsof contaminants of emerging concern in source and treateddrinking water samples
A national-scale survey of 247 contaminants of emerging concern (CECs), including organic and inorganic chemical compounds, andmicrobial contaminants, was conducted in source and treated drinkingwater samples from 25 treatment plants across the United States.Multiplemethodswere used to determine these CECs, including six analytical methods tomeasure 174 pharmaceuticals, personal care products, andAuthorsAngela L. Batt, Edward T. Furlong, Heath E. Mash, Susan T. Glassmeyer, Dana W. KolpinHuman health screening and public health significance of contaminants of emerging concern detected in public water supplies
The source water and treated drinking water from twenty five drinking water treatment plants (DWTPs) across the United States were sampled in 2010–2012. Samples were analyzed for 247 contaminants using 15 chemical and microbiological methods. Most of these contaminants are not regulated currently either in drinking water or in discharges to ambient water by the U. S. Environmental Protection AgencAuthorsRobert Benson, Octavia D. Conerly, William Sander, Angela L. Batt, J. Scott Boone, Edward T. Furlong, Susan T. Glassmeyer, Dana W. Kolpin, Heath MashMicrobial pathogens in source and treated waters from drinking water treatment plants in the United States and implications for human health
An occurrence survey was conducted on selected pathogens in source and treated drinking water collected from 25 drinking water treatment plants (DWTPs) in the United States. Water samples were analyzed for the protozoa Giardia and Cryptosporidium (EPA Method 1623); the fungi Aspergillus fumigatus, Aspergillus niger and Aspergillus terreus (quantitative PCR [qPCR]); and the bacteria Legionella pneuAuthorsDawn N. King, Maura J. Donohue, Stephen J. Vesper, Eric N. Villegas, Michael W. Ware, Megan E. Vogel, Edward Furlong, Dana W. Kolpin, Susan T. Glassmeyer, Stacy Pfaller