# WaterByCounty — U.S. County Water Quality Database

> WaterByCounty provides drinking water quality data, violation records, and safety ratings for every county in the United States, sourced from the EPA Safe Drinking Water Information System (SDWIS). Data covers water system violations, contaminant levels, and compliance history for all 3,143 U.S. counties.

WaterByCounty.com is part of the ByCounty Network, a platform combining government data across tax, cost of living, income, crime, health, schools, and environmental risk into county-level profiles. The flagship product is CountyScore.com, which aggregates all metrics into a single county score.

All data is free to access and sourced from the EPA ECHO database.

## Key Resources

- [Browse by State](https://waterbycounty.com): All 50 states with county-by-county water quality tables
- [Sitemap](https://waterbycounty.com/sitemap.xml): Complete index of all pages

## Data Coverage

- 3,143+ US counties across all 50 states and Washington D.C.
- Metrics per county: active violations count, health-based violations, monitoring violations, primary contaminants detected, population served by compliant vs. non-compliant systems
- Data source: EPA Safe Drinking Water Information System (SDWIS) via ECHO

## Data Attribution

All data sourced from: U.S. Environmental Protection Agency, Safe Drinking Water Information System (SDWIS). API: https://echo.epa.gov/

## Further Reading

- [CountyScore Network Hub](https://countyscore.com): Composite county scores combining all data dimensions
- [ByCounty Network llms.txt index](https://countyscore.com/llms.txt): All network sites and data sources
- [TaxByCounty](https://taxbycounty.com): Property tax rates by county