U.S. Water Quality Data by ZIP Code

Water quality violations, lead/copper levels, radon zones, and Home Safety Scores for 6,300+ U.S. ZIP codes.Based on EPA Safe Drinking Water Information System (SDWIS) data. Includes 90th percentile lead and copper levels from LCR sample results, county-level EPA radon zones, and a composite Home Safety Score (0-100, A-F grade).Updated weekly. Full methodology at zipcheckup.com/methodology.