Water Quality by State

Data source: EPA SDWIS Last verified: 2026-03-16

Browse water quality data by state. Each state page shows violation summaries, worst and best areas, and links to individual ZIP code reports.

Data source: EPA Safe Drinking Water Information System (SDWIS)

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51
States Covered
1989
ZIP Codes Tracked
AL 15 alerts 32 health IPC

Alabama

47 ZIP codes · 109 systems

1048 violations

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AK 6 alerts 138 health UPC

Alaska

40 ZIP codes · 80 systems

3917 violations

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AZ 242 health UPC

Arizona

46 ZIP codes · 166 systems

6790 violations · 5 rebate prog.

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AR 10 alerts 138 health IPC

Arkansas

47 ZIP codes · 128 systems

423 violations

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CA 5 alerts 80 health UPC

California

48 ZIP codes · 166 systems

348 violations

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CO 1 alert 98 health IPC

Colorado

46 ZIP codes · 182 systems

1262 violations · 6 rebate prog.

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CT 3 alerts 64 health IPC

Connecticut

34 ZIP codes · 83 systems

1696 violations

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DE 11 health IPC

Delaware

41 ZIP codes · 127 systems

70 violations · 2 rebate prog.

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DC 9 health IPC

District of Columbia

1 ZIP codes · 4 systems

70 violations · 2 rebate prog.

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FL 4 alerts 55 health IPC

Florida

48 ZIP codes · 167 systems

2318 violations

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GA 10 alerts 183 health IPC

Georgia

38 ZIP codes · 131 systems

562 violations · 5 rebate prog.

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HI 3 alerts 1 health UPC

Hawaii

28 ZIP codes · 51 systems

9 violations

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ID 77 health UPC

Idaho

37 ZIP codes · 96 systems

979 violations

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IL 10 alerts 78 health State-specific

Illinois

50 ZIP codes · 128 systems

900 violations

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IN 10 alerts 97 health IPC

Indiana

44 ZIP codes · 128 systems

832 violations · 5 rebate prog.

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IA 10 alerts 9 health IPC

Iowa

41 ZIP codes · 94 systems

204 violations

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KS 54 health IPC

Kansas

37 ZIP codes · 80 systems

305 violations

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KY 7 alerts 76 health State-specific

Kentucky

38 ZIP codes · 72 systems

143 violations

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LA 12 alerts 638 health State-specific

Louisiana

36 ZIP codes · 120 systems

811 violations

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ME 4 alerts 29 health IPC

Maine

27 ZIP codes · 70 systems

294 violations · 4 rebate prog.

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MD 1 alert 12 health IPC

Maryland

20 ZIP codes · 66 systems

133 violations

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MA 3 alerts 27 health State-specific

Massachusetts

45 ZIP codes · 79 systems

359 violations · 1 rebate prog.

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MI 11 alerts 35 health IPC

Michigan

49 ZIP codes · 164 systems

467 violations · 4 rebate prog.

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MN 6 alerts 65 health IPC

Minnesota

38 ZIP codes · 76 systems

155 violations

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MS 14 alerts 176 health IPC

Mississippi

45 ZIP codes · 147 systems

1402 violations

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MO 4 alerts 20 health IPC

Missouri

32 ZIP codes · 110 systems

270 violations

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MT 6 alerts 101 health IPC

Montana

33 ZIP codes · 91 systems

579 violations

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NE 3 alerts 76 health IPC

Nebraska

43 ZIP codes · 96 systems

156 violations

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NV 27 health IPC/UPC

Nevada

37 ZIP codes · 83 systems

259 violations

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NH 1 alert 89 health IPC

New Hampshire

41 ZIP codes · 130 systems

196 violations

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NJ 41 health NSPC

New Jersey

27 ZIP codes · 42 systems

901 violations

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NM 1 alert 278 health UPC

New Mexico

40 ZIP codes · 128 systems

1737 violations · 4 rebate prog.

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NY 3 alerts 130 health IPC

New York

35 ZIP codes · 122 systems

2413 violations · 4 rebate prog.

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NC 3 alerts 113 health IPC

North Carolina

48 ZIP codes · 181 systems

835 violations

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ND 1 health IPC

North Dakota

33 ZIP codes · 61 systems

92 violations

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OH 5 alerts 39 health IPC

Ohio

45 ZIP codes · 140 systems

255 violations

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OK 3 alerts 1376 health IPC

Oklahoma

48 ZIP codes · 145 systems

5499 violations

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OR 83 health UPC

Oregon

44 ZIP codes · 149 systems

1170 violations · 2 rebate prog.

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PA 2 alerts 41 health IPC

Pennsylvania

39 ZIP codes · 139 systems

3464 violations

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RI 2 alerts 54 health IPC

Rhode Island

27 ZIP codes · 58 systems

1657 violations · 4 rebate prog.

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SC 7 alerts 34 health IPC

South Carolina

42 ZIP codes · 128 systems

125 violations

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SD 24 health UPC

South Dakota

43 ZIP codes · 74 systems

107 violations

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TN 11 alerts 152 health IPC

Tennessee

44 ZIP codes · 106 systems

628 violations

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TX 17 alerts 493 health IPC

Texas

50 ZIP codes · 201 systems

1656 violations

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UT 17 health IPC

Utah

36 ZIP codes · 102 systems

1009 violations

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VT 7 health IPC

Vermont

40 ZIP codes · 92 systems

634 violations · 8 rebate prog.

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VA 4 alerts 18 health IPC

Virginia

38 ZIP codes · 125 systems

157 violations

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WA 4 alerts 51 health UPC

Washington

47 ZIP codes · 177 systems

995 violations

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WV 2 alerts 122 health IPC

West Virginia

25 ZIP codes · 50 systems

1263 violations

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WI 11 alerts 311 health State-specific

Wisconsin

49 ZIP codes · 142 systems

1219 violations

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WY 6 alerts 189 health IPC

Wyoming

32 ZIP codes · 64 systems

1137 violations

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Water quality data from the EPA Safe Drinking Water Information System (SDWIS). Updated daily.