Good — Average Score 78/100
State Overview
Water quality across Wisconsin receives an overall grade of B (Good) with an average score of 78 out of 100, based on EPA compliance data from 627 ZIP codes statewide. This is roughly in line with the national average of 75. Approximately 8% of ZIP codes (51 areas) receive a D or F grade, indicating communities with notable water quality concerns that warrant attention. The lowest-scoring area is ZIP code 53072 (Pewaukee) with a score of 27/100. Scores are calculated from EPA Safe Drinking Water Information System (SDWIS) violation records, lead and copper testing results, PFAS monitoring data from UCMR5, and enforcement actions over the past 5 years.
Lowest Scoring ZIP Codes