This leaderboard indexes the state’s almost 15,000 water systems by their own reported violation records across 15 years and 225,000 source documents.
Click any system name to open its full violation history on the map.
Severity
The cumulative "severity load" since 2010. It is the sum of every violation,
measured by how many times a contaminant exceeded its official MCL.
Example: In 2014, Silver Creek had 345 units of Radium where the limit is 5 (345 / 5 = 69x the limit). Combined with all other violations, they reached a total Severity of 360.21.
Yearly Severity
Total severity divided by years active. This lets us compare a system with only two years of data directly to one with fifteen.
Community Risk
A rating from 0–100 that blends Severity (70%) and Population (30%).
We weight Severity heavily so that small towns with dangerous water aren't buried by the sheer headcount of big cities.
* Systems with an unknown population are ranked by Severity only.
Data Integrity
We fixed several obvious typos (like values 1,000x higher than physically possible) from raw state data.
Entries with corrected data are marked with a ⓘ icon.