Water quality rankings
Rankings built directly from EPA Safe Drinking Water Act data and the Tap Grade. Every ranked figure is reproducible from the published data — each page states exactly how its metric is defined and how the data can be re-derived.
A ranking is a description of reported data, not a judgment of any operator. Absence of reported data is never counted as a clean result.
50 Cities With the Worst Tap Water (2026)
US cities ranked by the population-weighted average Tap Grade of the community water systems that report them as their location.
View ranking →Largest Water Systems With Unaddressed Health-Based Violations
The biggest community water systems that currently carry at least one unaddressed health-based Safe Drinking Water Act violation.
View ranking →States Ranked by Health-Based Violations per Capita
US states and territories ranked by health-based drinking-water violations per 100,000 people served over the most recent five-year window.
View ranking →Source: EPA SDWIS/ECHO + UCMR5 (see Methodology) · Data as of 2026Q2