I’ve spent a lot of time working with drinking water data. This page is meant to save others time as they start to research drinking water or work on water policy. If you’re brand new, I would recommend starting with EPA’s drinking water data clearinghouse.

The following data resources frequently come up in my work, but please feel free to get in touch if you have questions or need help finding drinking water data.

The Basics: SDWIS

The Safe Drinking Water Information System (SDWIS) is the go-to data source for information on drinking water systems in the US. For all public water systems, it includes information on their primary source water characteristics, number of people served, number of service connections, type of system for regulatory purposes, and information on all violations of the Safe Drinking Water Act.

Service Boundaries

Service boundaries are the geographic extent of a water system’s customer base. They have a ton of analytic uses. Many states post their service boundaries online, and these have been compiled and combined with modeled boundaries in the following EPA, SimpleLab/EPIC, and USGS datasets.

Safe Drinking Water Act Compliance Monitoring Samples

Drinking water systems collect samples of raw and finished drinking water for hundreds of water quality parameters. Some states post these samples publicly, and many use a Drinking Water Watch or Drinking Water Viewer website. EPA has compiled a list of these state websites if you’d like to check them out.

EPA has also assembled drinking water sampling data as part of the National Contaminant Occurrence Database. There are additional datasets that cover some or all of the US.

  • Six Year Review: As part of the Safe Drinking Water Act, which requires the US EPA to regularly revisit and reconsider its drinking water standards, EPA collects SDWA compliance samples through an information collection request of primacy agencies (i.e., states). It currently covers 1998 - 2019, although coverage varies by state and contaminant over time.
  • Unregulated Contaminant Monitoring Rule Data: The UCMR is used to collect occurrence information for contaminants that are not regulated as part of the Safe Drinking Water Act at the time of sampling. Contaminant data has been collected in five separate waves from 2001 - 2025. The UCMR uses a representative sampling protocol across public water systems, thus coverage is more limited across sytems than for the SYR. Each wave of sampling is also limited to a specific set of target contaminants.

Other datasets featuring drinking water sampling information include:

Private Domestic Wells

Private domestic wells are not regulated under the Safe Drinking Water Act, and so they’re an important potential area of study. First, however, you have to know where the wells are. The following study can help in this regard, and you can find the underlying data for the project here.

  • Murray, A., Hall, A., Weaver, J., and Kremer, F.. 2021. “ Methods for Estimating Locations of Housing Units Served by Private Domestic Wells in the United States Applied to 2010.” Journal of the American Water Resources Association 57( 5): 828– 843. https://doi.org/10.1111/1752-1688.12937.

Other Research Data

Here are links to publicly-available datasets produced by researchers:

  • Allaire, Maura, 2018, “Health-Based Violations of the Safe Drinking Water Act, 1982-2015”, https://doi.org/10.7910/DVN/IFV6SQ, Harvard Dataverse, V1.
  • Allaire, Maura, 2019, “Bottled Water Sales and Water Quality Violations, 2006-2015”, https://doi.org/10.7910/DVN/HDYIRY, Harvard Dataverse, V1.
  • Hughes, Sara; Kirchhoff, Christine; Conedera, Katelynn; Friedman, Mirit, 2023, “The Municipal Drinking Water Database, 2000-2018 [United States]”, https://doi.org/10.7910/DVN/DFB6NG, Harvard Dataverse, V1.

Disclaimer:

This unofficial page just links to publicly-available data. It is not an endorsement of any product, it does not advocate for any organization, and it provides no warranty for the suitability of use of the above information for any specific purpose.