The 10 States With the Worst Tap Water (2026)

The score is population-weighted from city-level EPA violation data — 100 means no contaminants above EPA limits or health guidelines. The violations column counts health-based violations per community water system in 2024. Here are the ten states at the bottom of the table — the worst in the country as of July 2026 — with every figure linking to that state's full breakdown.

#1: Oklahoma

Oklahoma ranks near the bottom for tap water quality — its score of 72.6/100 puts it #51 of 51, though its water systems averaged 3.5 health-based violations each in 2024, worse than the U.S. average of 2.5. That average reflects contaminants exceeding EPA limits or health guidelines in a meaningful share of its cities.

#2: Pennsylvania

Pennsylvania ranks near the bottom for tap water quality — its score of 75.9/100 puts it #50 of 51, and its water systems averaged 1.6 health-based violations each in 2024 — better than the U.S. average of 2.5. That average reflects contaminants exceeding EPA limits or health guidelines in a meaningful share of its cities.

#3: Nevada

Nevada ranks near the bottom for tap water quality — its score of 76.1/100 puts it #49 of 51, though its water systems averaged 4.2 health-based violations each in 2024, worse than the U.S. average of 2.5. That average reflects contaminants exceeding EPA limits or health guidelines in a meaningful share of its cities.

See the full table

All 51 states are ranked on the tap water quality index page, and every state links to a detailed local breakdown. Scores describe states — your utility's Consumer Confidence Report has your exact numbers.