US States Water Quality Rankings
Explore water quality data for all 50 US states. States are ranked by average water quality score based on EPA SDWIS data for 7,929 public water systems.
Trending Cities
1
Washington
WA · 480 systems · 9.4M people
94 A
2
North Dakota
ND · 93 systems · 0.7M people
92 A
3
South Dakota
SD · 115 systems · 0.8M people
91 A
4
Maryland
MD · 161 systems · 5.3M people
90 A
5
Nebraska
NE · 139 systems · 1.6M people
90 A
6
California
CA · 1,081 systems · 40.9M people
89 B
7
Michigan
MI · 582 systems · 7.3M people
89 B
8
South Carolina
SC · 249 systems · 4.7M people
89 B
9
Maine
ME · 92 systems · 0.6M people
87 B
10
Minnesota
MN · 362 systems · 4.5M people
87 B
11
Delaware
DE · 40 systems · 0.5M people
86 B
12
New Hampshire
NH · 99 systems · 0.8M people
85 B
13
Virginia
VA · 295 systems · 7.0M people
85 B
14
Wisconsin
WI · 313 systems · 2.9M people
85 B
15
Montana
MT · 125 systems · 0.8M people
84 B
16
Ohio
OH · 578 systems · 10.1M people
84 B
17
Wyoming
WY · 74 systems · 0.5M people
84 B
18
Alabama
AL · 440 systems · 6.3M people
83 B
19
Indiana
IN · 432 systems · 5.2M people
83 B
20
New York
NY · 679 systems · 18.0M people
83 B
21
Oregon
OR · 234 systems · 3.7M people
83 B
22
Tennessee
TN · 385 systems · 7.0M people
83 B
23
Colorado
CO · 327 systems · 7.0M people
82 B
24
Georgia
GA · 429 systems · 10.4M people
82 B
25
Vermont
VT · 85 systems · 0.4M people
81 B
26
Arkansas
AR · 370 systems · 2.9M people
80 B
27
Idaho
ID · 126 systems · 1.5M people
80 B
28
Hawaii
HI · 65 systems · 1.5M people
79 B
29
Kansas
KS · 279 systems · 2.7M people
78 B
30
Missouri
MO · 523 systems · 5.6M people
78 B
31
Connecticut
CT · 104 systems · 2.8M people
77 B
32
Texas
TX · 2,237 systems · 32.7M people
76 B
33
Mississippi
MS · 609 systems · 3.0M people
75 B
34
North Carolina
NC · 470 systems · 9.4M people
75 B
35
Massachusetts
MA · 321 systems · 10.0M people
74 C
36
Nevada
NV · 114 systems · 3.4M people
74 C
37
Iowa
IA · 335 systems · 2.8M people
72 C
38
Pennsylvania
PA · 746 systems · 11.5M people
71 C
39
Rhode Island
RI · 40 systems · 1.1M people
67 C
40
Illinois
IL · 856 systems · 11.6M people
66 C
41
New Jersey
NJ · 364 systems · 8.9M people
66 C
42
Kentucky
KY · 334 systems · 5.1M people
65 C
43
Louisiana
LA · 500 systems · 5.1M people
65 C
44
Florida
FL · 627 systems · 21.9M people
64 C
45
Utah
UT · 217 systems · 3.7M people
62 C
46
New Mexico
NM · 166 systems · 1.9M people
61 C
47
Arizona
AZ · 331 systems · 4.9M people
55 D
48
West Virginia
WV · 214 systems · 0.9M people
52 D
49
Oklahoma
OK · 397 systems · 3.4M people
38 F
50
Alaska
AK · 52 systems · 0.6M people
8 F
State water quality FAQs
Which US states have the best drinking water quality? +
WaterQ ranks states by average system score from EPA SDWIS data. Open a state page to review score breakdowns, violations, and top-performing systems.
How often are state water quality rankings updated? +
State rankings refresh when new EPA SDWIS data is processed. Check each page for the latest update context and compare against other states.
Can I compare cities or systems inside a state? +
Yes. From each state page you can drill into cities and public water systems, then compare quality metrics, grades, and violation histories.
Next steps: explore the national rankings, browse city-level reports, or use search to find a specific water system.