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.