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Water Systems by State

49,358 community water systems across all 50 states, ranked by violation rates. Click a state to see individual water system details.

Water Systems
49,358
Population Served
330,901,233
Health-Based Violation Records
205,941
States Tracked
56

States Ranked by Violation Rate

# State Systems Health Viol. Systems % with Violations
1 Oklahoma 882 811 92%
2 U.S. Virgin Islands 77 64 83.1%
3 Puerto Rico 402 324 80.6%
4 New Mexico 593 445 75%
5 American Samoa 10 7 70%
6 Vermont 379 262 69.1%
7 Alaska 406 276 68%
8 Louisiana 815 544 66.7%
9 District of Columbia 11 7 63.6%
10 West Virginia 427 271 63.5%
11 Guam 5 3 60%
12 Nebraska 593 351 59.2%
13 Arkansas 662 377 56.9%
14 Kentucky 375 195 52%
15 South Dakota 513 261 50.9%
16 Utah 553 272 49.2%
17 Connecticut 505 238 47.1%
18 Arizona 949 435 45.8%
19 Nevada 230 105 45.7%
20 Rhode Island 93 42 45.2%
21 Pennsylvania 1,783 790 44.3%
22 Kansas 855 370 43.3%
23 Wisconsin 978 422 43.1%
24 New Hampshire 681 287 42.1%
25 Oregon 943 396 42%
26 Massachusetts 564 236 41.8%
27 California 3,068 1,274 41.5%
28 Idaho 773 313 40.5%
29 Colorado 1,109 439 39.6%
30 Texas 4,620 1,807 39.1%
31 Maryland 481 187 38.9%
32 Wyoming 317 123 38.8%
33 Illinois 1,785 660 37%
34 Northern Mariana Islands 36 13 36.1%
35 Indiana 712 253 35.5%
36 New York 2,242 771 34.4%
37 Missouri 1,688 576 34.1%
38 North Carolina 1,958 656 33.5%
39 New Jersey 623 206 33.1%
40 Mississippi 989 316 32%
41 Maine 360 115 31.9%
42 South Carolina 558 164 29.4%
43 Tennessee 454 131 28.9%
44 Ohio 1,089 308 28.3%
45 Florida 1,513 409 27%
46 Montana 818 201 24.6%
47 Michigan 1,434 337 23.5%
48 Delaware 207 48 23.2%
49 Virginia 1,050 237 22.6%
50 North Dakota 318 56 17.6%
51 Alabama 546 94 17.2%
52 Hawaii 118 16 13.6%
53 Washington 2,410 304 12.6%
54 Minnesota 998 121 12.1%
55 Georgia 1,722 200 11.6%
56 Iowa 1,078 121 11.2%

Frequently Asked Questions

How many public water systems are in the United States?
The EPA tracks 49,358 community water systems serving approximately 330,901,233 people across the United States.
What are health-based water violations?
Health-based violations include Maximum Contaminant Level (MCL) violations, where a contaminant exceeds the legal limit, and Treatment Technique (TT) violations, where a required treatment process was not properly followed. These violations may pose a direct risk to public health.
Where does this water quality data come from?
All water system and violation data comes from the EPA Safe Drinking Water Information System (SDWIS), the federal database that tracks compliance of all public water systems in the United States.

About This Data

Water system data is from the EPA Safe Drinking Water Information System (SDWIS). Health-based violations include Maximum Contaminant Level (MCL) and Treatment Technique (TT) violations. Only community water systems (CWS) are included.

Source: U.S. Environmental Protection Agency, SDWIS Federal Reporting Services U.S. Environmental Protection Agency, SDWIS Federal Reporting Services