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 interested in additional data that you don’t see here, please feel free to get in touch!

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 active water systems, it includes information on their primary sourcewater characteristics, number of people served, number of service connections, type of system for regulatory purposes, and of course 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 publicly, and these have been compiled and combined with modeled boundaries in the following SimpleLab/EPIC dataset. There is also another dataset on public supply water service areas produced by the US Geological Survey linked below as well.

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 website. I’ve compiled a list of these websites if you’d like to check them out.

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). After significant data quality assurance and control protocols, this data is posted publicly.
    • Six Year Review 2: SYR2 includes samples from 1998 to 2005.
    • Six Year Review 3: SYR3 includes samples from 2006-2011.
    • Six Year Review 4: The full SYR4 dataset is not yet available, however you can download a preliminary version of the data covering certain disinfectant byproduct and bacteriological samples at the above link.
  • The National Environmental Public Health Tracking Network: The CDC collects information on 12 drinking water contaminants of concern from 28 states over 2001-2021. The tracking tool allows easy download after customizing your data query.
  • Environmental Working Group Tap Water Databse: Another resource for finding information on drinking water quality.

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 PDWs 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, UNF:6:vaLp8XxepUoSL4lAJyeu4Q== [fileUNF]
  • Allaire, Maura, 2019, “Bottled Water Sales and Water Quality Violations, 2006-2015”, https://doi.org/10.7910/DVN/HDYIRY, Harvard Dataverse, V1, UNF:6:hEbKPWtT6uqIZ+75fd/MkQ== [fileUNF]
  • 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, UNF:6:vyfBObHyAjqPejesGH3sEA== [fileUNF]


This page 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.