About WaterByCounty
WaterByCounty provides drinking water quality data for every county in the United States. Our goal is to make EPA water safety data accessible to homeowners, renters, and families researching water quality in their area.
We track health-based violations, violation rates, and calculate water quality scores (0–100) and letter grades (A–F) for each county. Higher scores mean better water quality.
Water data is sourced from the EPA Safe Drinking Water Information System (SDWIS), which tracks compliance by public water systems nationwide.
WaterByCounty is part of the ByCounty Network, a collection of county-data sites powered by free government APIs.
AI-Generated Content Disclosure
WaterByCounty uses artificial intelligence to generate descriptive narratives and editorial summaries on county and state pages. These AI-generated texts are based on real EPA data and are reviewed for accuracy, but they are machine-written summaries — not expert analysis. All data tables, scores, grades, and numeric values come directly from EPA SDWIS data processed through our scoring pipeline. The AI layer adds context and readability but does not alter the underlying data.
For full details on our data sources and scoring approach, see our Methodology page.