Tap Water Quality Across the Great Plains: Every State Ranked
How 5 Great Plains states compare on tap water quality, from South Dakota to Oklahoma, with July 2026 figures.
Within the Great Plains, tap water quality spans from South Dakota (96.5/100) to Oklahoma (72.6/100) against a national benchmark of 84.5/100. Here's the regional table as of July 2026, best-ranked first.
| Regional rank | State | Quality score /100 | National rank |
|---|---|---|---|
| 1 | South Dakota | 96.5/100 | #6 of 51 |
| 2 | North Dakota | 84.0/100 | #23 of 51 |
| 3 | Nebraska | 81.3/100 | #35 of 51 |
| 4 | Kansas | 76.1/100 | #48 of 51 |
| 5 | Oklahoma | 72.6/100 | #51 of 51 |
The regional standout: South Dakota
South Dakota has some of the best tap water in the country — a quality score of 96.5/100 ranks #6 of 51, and its water systems averaged 1.1 health-based violations each in 2024 — better than the U.S. average of 2.5.
The regional laggard: 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.
Compare any state in detail on the tap water quality index.
Averages describe states, not your faucet. A certified home water test screens for lead, nitrates, bacteria and dozens of other contaminants — the same categories EPA regulates.
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