Drop by Drop

Combined, the last seven years of research on drinking water in the US have provided information on the occurrence of multiple contaminants from a variety of potential sources in tapwaters sampled across the United States. Samples were taken from homes (residential), places of work (commercial), and from facilities treating drinking water (pre-distribution) served by both surface water (SW) and ground water (GW) sources.

The interactive map below depicts these results along with detailed information by site for the currently completed studies.

These studies are conducted in collaboration with multiple federal, state, and local agencies including the Environmental Protection Agency (EPA), Food and Drug Administration (FDA), National Cancer Institute (NCI), National Institute of Allergy and Infectious Disease (NIAID), National Institute of Environmental Health Science (NIEHS), Tribal Nations, universities, water utilities, communities, and others.

To understand potential exposures to PFAS at the point-of-use, 716 locations (269 private-well; 447 public supply) were sampled across the US between 2016 and 2021. Results from this national reconnaissance, including data on potential PFAS sources, are compiled and displayed in a separate  interactive dashboard .

For more information on USGS drinking water studies, please contact Paul Bradley ( pbradley@usgs.gov ) and Kelly Smalling ( ksmall@usgs.gov ).

Bradley et al., 2018. Reconnaissance of Mixed Organic and Inorganic Chemicals in Private and Public Supply Tapwaters at Selected Residential and Workplace Sites in the United States. Environmental Science and Technology,  https://doi.org/10.1021/acs.est.8b04622 

Bradley et al., 2020. Mixed organic and inorganic tapwater exposures and potential effects in greater Chicago area, USA. Science of the Total Environment,  https://doi.org/10.1016/j.scitotenv.2020.1372 

Bradley et al., 2021. Public and private tapwater: Comparative analysis of contaminant exposure and potential risk, Cape Cod, Massachusetts, USA. Environment International,  https://doi.org/10.1016/j.envint.2021.10648 

Bradley et al., 2021. Pilot-scale expanded assessment of inorganic and organic tapwater exposures and predicted effects in Puerto Rico, USA. Science of the Total Environment.  https://doi.org/10.1016/j.scitotenv.2021.147721 

Bradley et al., 2022. Tapwater exposures, effects potential, and residential risk management in Northern Plains Nations. ACS ES&T Water.  https://doi.org/10.1021/acsestwater.2c00293 

Bradley et al., 2023. Juxtaposition of intensive agriculture, vulnerable aquifers, and mixed chemical/microbial exposures in private-well tapwater in northeast Iowa. Science of the Total Environment.  https://doi.org/10.1016/j.scitotenv.2023.161672 

Bradley et al., 2023. Bottled water contaminant exposures and potential human effects. Environment International.  https://doi.org/10.1016/j.envint.2022.107701 

Gordon, et al., 2023. Interactive PFAS Dashboard.  https://geonarrative.usgs.gov/pfasustapwater/