Water Quality by State: Complete U.S. Rankings
Compare water quality across all U.S. states. See average water quality scores, top-ranked cities in each state, and regional water quality patterns. Click any state to explore all cities and detailed water quality data.
National Overview
39
States with Data
899
Cities Analyzed
86
National Avg Score
124M
People Analyzed
Top 10 States with Best Water Quality
#1
Michigan
3 cities • 4,435,000 people served
Top city: Detroit (95/100)
95
A+
Avg Score
#2
Minnesota
1 cities • 420,000 people served
Top city: Minneapolis (95/100)
95
A+
Avg Score
#3
Missouri
2 cities • 1,730,000 people served
Top city: Kansas City (95/100)
95
A+
Avg Score
#4
Nebraska
1 cities • 500,000 people served
Top city: Omaha (95/100)
95
A+
Avg Score
#5
Nevada
1 cities • 2,300,000 people served
Top city: Las Vegas (95/100)
95
A+
Avg Score
#6
New Mexico
1 cities • 680,000 people served
Top city: Albuquerque (95/100)
95
A+
Avg Score
#7
Ohio
5 cities • 4,400,000 people served
Top city: Akron (95/100)
95
A+
Avg Score
#8
Oklahoma
2 cities • 1,180,000 people served
Top city: Oklahoma City (95/100)
95
A+
Avg Score
#9
Oregon
3 cities • 200,051 people served
Top city: Eugene (95/100)
95
A+
Avg Score
#10
Utah
8 cities • 1,670,000 people served
Top city: Ogden (95/100)
95
A+
Avg Score
States with Most Water Quality Concerns
#30
Colorado
35 cities • 3,675,915 people affected
Best city: Longmont (96/100)
76
B
Avg Score
#31
Virginia
1 cities • 229,395 people affected
Best city: Richmond (77/100)
77
B
Avg Score
#32
Louisiana
30 cities • 1,708,978 people affected
Best city: Hammond (96/100)
77
B
Avg Score
#33
Idaho
20 cities • 1,011,043 people affected
Best city: Coeur d'Alene (95/100)
78
B
Avg Score
#34
Georgia
40 cities • 2,901,545 people affected
Best city: Alpharetta (96/100)
78
B
Avg Score
#35
Florida
96 cities • 8,727,925 people affected
Best city: Dunedin (96/100)
78
B
Avg Score
#36
Alaska
10 cities • 410,660 people affected
Best city: Sitka (93/100)
78
B
Avg Score
#37
Illinois
60 cities • 6,321,081 people affected
Best city: Romeoville (98/100)
79
B
Avg Score
#38
Arizona
40 cities • 5,474,285 people affected
Best city: Payson (98/100)
79
B
Avg Score
#39
Kansas
25 cities • 1,722,561 people affected
Best city: Salina (97/100)
80
B+
Avg Score
Complete State Rankings
Click any state to explore all cities and detailed water quality data
| Rank | State | Avg Score | Grade | Cities | Score Range | Population |
|---|---|---|---|---|---|---|
| #1 | Michigan | 95 | A+ | 3 | 95 - 95 | 4,435,000 |
| #2 | Minnesota | 95 | A+ | 1 | 95 - 95 | 420,000 |
| #3 | Missouri | 95 | A+ | 2 | 95 - 95 | 1,730,000 |
| #4 | Nebraska | 95 | A+ | 1 | 95 - 95 | 500,000 |
| #5 | Nevada | 95 | A+ | 1 | 95 - 95 | 2,300,000 |
| #6 | New Mexico | 95 | A+ | 1 | 95 - 95 | 680,000 |
| #7 | Ohio | 95 | A+ | 5 | 95 - 95 | 4,400,000 |
| #8 | Oklahoma | 95 | A+ | 2 | 95 - 95 | 1,180,000 |
| #9 | Oregon | 95 | A+ | 3 | 95 - 95 | 200,051 |
| #10 | Utah | 95 | A+ | 8 | 95 - 95 | 1,670,000 |
| #11 | Washington | 95 | A+ | 4 | 95 - 95 | 2,430,000 |
| #12 | Wisconsin | 95 | A+ | 1 | 95 - 95 | 820,000 |
| #13 | New York | 93 | A | 5 | 86 - 95 | 11,141,000 |
| #14 | North Carolina | 92 | A | 5 | 86 - 95 | 2,186,176 |
| #15 | Pennsylvania | 91 | A | 4 | 78 - 95 | 2,230,380 |
| #16 | Texas | 88 | A- | 11 | 65 - 97 | 9,176,377 |
| #17 | Alabama | 83 | B+ | 25 | 68 - 96 | 1,710,306 |
| #18 | Arkansas | 83 | B+ | 20 | 69 - 97 | 1,154,104 |
| #19 | Delaware | 83 | B+ | 10 | 59 - 95 | 218,074 |
| #20 | Iowa | 83 | B+ | 25 | 64 - 96 | 1,419,752 |
| #21 | Maine | 83 | B+ | 15 | 69 - 95 | 375,765 |
| #22 | Maryland | 83 | B+ | 35 | 50 - 98 | 2,233,992 |
| #23 | Massachusetts | 83 | B+ | 50 | 54 - 96 | 3,750,253 |
| #24 | Connecticut | 82 | B+ | 25 | 67 - 97 | 1,602,775 |
| #25 | Hawaii | 81 | B+ | 15 | 67 - 92 | 778,599 |
| #26 | Indiana | 81 | B+ | 40 | 46 - 97 | 3,126,303 |
| #27 | Kentucky | 81 | B+ | 30 | 46 - 97 | 1,715,759 |
| #28 | Tennessee | 81 | B+ | 2 | 67 - 95 | 7,922 |
| #29 | California | 80 | B+ | 193 | 44 - 98 | 28,240,268 |
| #30 | Kansas | 80 | B+ | 25 | 48 - 97 | 1,722,561 |
| #31 | Arizona | 79 | B | 40 | 51 - 98 | 5,474,285 |
| #32 | Illinois | 79 | B | 60 | 47 - 98 | 6,321,081 |
| #33 | Alaska | 78 | B | 10 | 56 - 93 | 410,660 |
| #34 | Florida | 78 | B | 96 | 47 - 96 | 8,727,925 |
| #35 | Georgia | 78 | B | 40 | 44 - 96 | 2,901,545 |
| #36 | Idaho | 78 | B | 20 | 66 - 95 | 1,011,043 |
| #37 | Louisiana | 77 | B | 30 | 52 - 96 | 1,708,978 |
| #38 | Virginia | 77 | B | 1 | 77 - 77 | 229,395 |
| #39 | Colorado | 76 | B | 35 | 45 - 96 | 3,675,915 |
Understanding Regional Water Quality Patterns
Water quality varies significantly by region due to geography, source water, infrastructure age, and environmental factors:
Geographic Factors
- • Arid regions often have more mineral content and natural contaminants
- • Agricultural areas face higher nitrate and pesticide levels
- • Mountainous regions typically have cleaner source water
- • Coastal areas may have saltwater intrusion issues
Infrastructure Age
- • Older industrial states often have aging pipe systems
- • Rapidly growing areas may have newer infrastructure
- • Lead pipes remain in many pre-1986 systems
- • Rural areas may lack modern treatment facilities
Source Water Type
- • Surface water requires more extensive treatment
- • Groundwater often has higher mineral content
- • Protected watersheds provide cleaner source water
- • Mixed sources offer supply diversification
Economic Factors
- • Wealthier areas invest more in infrastructure upgrades
- • Large utilities can afford better treatment technology
- • Small rural systems may struggle with compliance
- • State funding priorities affect water quality