PlainWater

About PlainWater

Our Mission

We believe that knowing what is in your drinking water should not require a science degree or a public records request. PlainWater exists because the EPA collects detailed compliance, violation, and contaminant testing data for every public water system in America – but that data is locked inside bulk downloads, technical databases, and government portals that most people will never navigate. We built PlainWater to make this information accessible to everyone.

Our philosophy is simple: present EPA water quality data as reported, organized by water system, county, and state, so you can quickly see the violation history and contaminant testing results for the system that serves your home. We do not filter, editorialize, or score water systems beyond what the EPA's own records show. The data is the story.

Why we built this: over 143,000 public water systems serve communities across the United States, and many have violation histories that their customers never learn about. The introduction of PFAS "forever chemical" testing under the UCMR5 program has revealed widespread contamination that is only now being documented. PlainWater puts this data in your hands – free, searchable, and updated regularly so you can make informed decisions about the water your family drinks.

Our Data Sources

All data on PlainWater comes directly from official U.S. Environmental Protection Agency programs. We do not use estimates, third-party assessments, or consumer reviews. Our specific data sources are:

  • Safe Drinking Water Information System (SDWIS) – The EPA's comprehensive database of public water system information, including system characteristics, violation records, and enforcement actions. We download quarterly bulk data exports from EPA's Enforcement and Compliance History Online (ECHO) program at echo.epa.gov. The SDWIS dataset includes four primary files: public water system records (SDWA_PUB_WATER_SYSTEMS), violation and enforcement records (SDWA_VIOLATIONS_ENFORCEMENT), geographic area mappings (SDWA_GEOGRAPHIC_AREAS), and reference code values for contaminant names and violation categories (SDWA_REF_CODE_VALUES).
  • Fifth Unregulated Contaminant Monitoring Rule (UCMR5) – The EPA's nationwide monitoring program for contaminants not yet regulated under the Safe Drinking Water Act. UCMR5 focuses heavily on per- and polyfluoroalkyl substances (PFAS), commonly known as "forever chemicals." We process the complete UCMR5 occurrence dataset published by the EPA at epa.gov/dwucmr, which contains approximately 1.9 million individual test results from water systems across the country (testing period 2023 through 2025).

How We Process the Data

Our approach to data processing is designed for accuracy, completeness, and transparency. Here is how raw EPA files become the searchable profiles on PlainWater:

Data acquisition: We download quarterly SDWIS bulk data exports from EPA's ECHO program. These arrive as large CSV files in a single ZIP archive. Separately, we download the UCMR5 PFAS occurrence dataset, which is published as a tab-delimited text file encoded in Latin-1 format. Both sources are fetched in their original formats without modification.

Parsing and normalization: SDWIS CSV files are parsed and loaded into a structured dataset. Water system records are linked to their geographic areas (counties, states) using EPA geographic crosswalk tables. Violation records are categorized using EPA reference codes into health-based violations (Maximum Contaminant Level exceedances, treatment technique failures) and monitoring/reporting violations. The UCMR5 dataset requires special handling for its Latin-1 encoding and tab-delimited format before loading approximately 1.9 million PFAS test results.

Aggregation and indexing: Each water system profile aggregates its complete violation history and any available PFAS testing results. County and state summary pages are built from system-level data to show regional compliance patterns. Contaminant profiles track detection frequencies across systems nationwide. All data is indexed for fast search by system name, county, state, and contaminant.

PFAS analysis: Where UCMR5 data is available, we display individual PFAS analyte concentrations and compare them to EPA health advisory levels. Detection results are presented as published by the EPA – we do not compute composite PFAS scores or make safety determinations beyond what the data itself shows.

Data Currency

PlainWater's data freshness depends on the update schedule of each EPA program:

  • SDWIS data: The EPA publishes updated SDWIS bulk downloads quarterly through the ECHO program. We refresh our database approximately every 90 days after new data becomes available. Current data reflects the most recent quarterly release.
  • UCMR5 PFAS data: The EPA updates UCMR5 occurrence data periodically as new test results are reported by participating water systems. The testing period runs from 2023 through 2025. We update our PFAS data annually or when the EPA publishes significant new results.

There is always a lag between when water quality events occur, when they are reported to state agencies, when states submit data to the EPA, and when the EPA publishes updated files. For urgent water quality concerns, always contact your local water utility or state drinking water program directly.

Editorial Independence & How Content Is Produced

Content on PlainWater is compiled by our editorial team from official source data. Raw data from NOAA, USGS, EPA, and related environmental agencies is transformed into readable profiles, then validated against the source before publication. The PlainWater editorial team, is responsible for editorial standards, methodology, and corrections.

We do not accept payment, sponsorship, or promoted placement from government agencies, environmental organizations, or any covered entity. Our only revenue source is contextual display advertising served by Google AdSense, advertisers do not influence which entities we cover or how we present data, and they do not receive preferential placement.

Limitations and Disclaimers

Understanding the boundaries of this data is critical for responsible use. Key limitations include:

  • Violation records are not real-time: SDWIS violations reflect what has been formally reported and recorded. Active violations may not appear immediately, and resolved violations may still show in historical records. The absence of violations does not guarantee that a water system is currently meeting all standards.
  • PFAS testing is not universal: UCMR5 testing covers water systems serving populations of 3,300 or more, plus a sample of smaller systems. Many smaller community water systems have not been tested for PFAS under this program. No PFAS data for a system does not mean PFAS is absent.
  • Private wells are excluded: SDWIS only covers public water systems. The approximately 43 million Americans who rely on private wells are not represented in this data at all. Private well owners must arrange their own testing.
  • Reporting gaps exist: Not all water systems report complete data every quarter. Some violations may be underreported due to monitoring gaps, delayed laboratory results, or administrative backlogs at the state level.
  • Data does not equal health risk: A violation record indicates that a regulatory standard was exceeded, but the health impact depends on the specific contaminant, concentration, duration of exposure, and individual vulnerability factors. PlainWater does not make health risk assessments.

Important: PlainWater is not affiliated with the U.S. Environmental Protection Agency (EPA), any state agency, or any water utility. Data is provided for informational purposes only and does not constitute health, safety, or legal advice. Always consult your local water utility or state drinking water program for the most current water quality information affecting your household.

Contact

We welcome questions about our data sources, methodology, or the information displayed on PlainWater. If you spot an error in a water system record, have feedback on how we present the data, or want to understand how a specific data point was derived, we want to hear from you. We are also happy to assist journalists, public health researchers, and community advocates who use our data in their work.

Email us at hello@plainwaterdata.com.

PlainWater is an independent publisher, a data intelligence company that builds free, public-interest data portals. We transform complex government datasets into accessible, searchable resources for researchers, journalists, policymakers, and the public.