State Water Quality Rankings 2026

Compare tap water quality across all 50 US states and Washington D.C. Rankings based on population-weighted scores from city-level EPA data.

Key Findings

Best Water Quality

Hawaii

Score: 99.9 (Grade A)

National Average

84.5

Out of 100 points possible

Most Room for Improvement

Oklahoma

Score: 72.6 (Grade B)

All States Ranked

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Rank	State	Grade	Score	Cities Tested	Population
1	Hawaii	A	99.9	30	10,393,426
2	North Carolina	A	99.7	260	32,288,327
3	New Hampshire	A	99.5	37	640,451
4	Louisiana	A	98.9	141	6,517,644
5	Alaska	A	97.7	13	420,015
6	South Dakota	A	96.5	38	480,246
7	New Mexico	A	95.9	69	5,465,379
8	Indiana	A	95.2	164	26,818,524
9	Oregon	A	90.5	110	7,978,872
10	Vermont	A	88.2	26	109,055
11	Tennessee	A	87.6	183	16,002,403
12	Massachusetts	A	87.3	166	7,307,382
13	Colorado	A	86.7	156	57,172,929
14	Rhode Island	A	85.8	18	892,579
15	Maine	A	85.6	39	493,369
16	Washington	A	85.6	262	37,460,278
17	Maryland	A	85.4	133	64,990,436
18	District of Columbia	A	85.0	1	665,214
19	Georgia	A	84.8	218	42,789,537
20	Mississippi	A	84.6	128	1,814,205
21	Wyoming	A	84.3	23	288,327
22	Alabama	A	84.1	186	6,756,463
23	North Dakota	A	84.0	29	531,888
24	Arkansas	A	83.7	142	7,982,065
25	California	A	83.7	765	236,998,735
26	South Carolina	A	83.4	137	17,248,317
27	Michigan	A	83.1	205	12,294,604
28	New York	A	83.1	357	89,997,343
29	Virginia	A	83.0	172	38,896,277
30	Montana	A	82.4	29	416,712
31	West Virginia	A	82.3	68	845,071
32	Iowa	A	81.7	128	8,318,498
33	Idaho	A	81.7	53	2,963,071
34	Delaware	A	81.3	29	5,648,314
35	Nebraska	A	81.3	45	1,140,191
36	Ohio	A	81.0	266	45,758,445
37	Florida	A	80.6	386	76,275,724
38	Kentucky	A	80.5	114	7,977,671
39	Connecticut	A	80.1	105	26,913,772
40	New Jersey	B	79.8	402	113,905,849
41	Minnesota	B	78.8	182	5,181,179
42	Texas	B	78.1	647	58,553,444
43	Wisconsin	B	77.7	173	4,653,277
44	Arizona	B	77.4	87	24,899,771
45	Utah	B	77.3	90	5,225,355
46	Illinois	B	76.8	315	22,194,246
47	Missouri	B	76.2	186	14,687,665
48	Kansas	B	76.1	125	10,788,981
49	Nevada	B	76.1	27	5,597,760
50	Pennsylvania	B	75.9	589	157,219,393
51	Oklahoma	B	72.6	154	10,205,847

Methodology

State rankings are calculated using population-weighted average water quality scores from city-level data. Each city's score (0-100) is based on contaminant levels relative to EPA guidelines, with higher scores indicating better water quality. Grades are assigned as: A (80+), B (60-79), C (40-59), D (20-39), F (<20).

Data Sources

EPA Safe Drinking Water Information System (SDWIS) violation data
Annual Consumer Confidence Reports from water utilities
State environmental agency databases
City-level water quality testing results for 9,500+ cities

Scoring Criteria

Each state's score is calculated as a population-weighted average of city scores. City scores (0-100) are based on:

Number of contaminants exceeding EPA Maximum Contaminant Levels (MCLs)
Number of contaminants exceeding health guidelines (MCLGs)
Severity and frequency of violations
Overall water system compliance history

Last updated: January 26, 2026

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