Cities with the Most Contaminants Detected

These cities have the highest number of unique contaminants detected in violation of EPA standards. A higher count means more different types of substances have exceeded safe levels, which can indicate diverse contamination sources or aging infrastructure.

# ▴▾ City ▴▾ State ▴▾ Contaminants ▴▾ Violations ▴▾ Population ▴▾
1 Monument Valley UT 63 795 1,303
2 BROOKINGS SD 53 724 23,603
3 RAPID CITY SD 51 602 91,187
4 ORAL SD 50 210 1,057
5 SUMMIT SD 50 178 382
6 ABERDEEN,CARPENTER SD 50 312 217
7 GLENCROSS,MOBRIDGE SD 50 210 166
8 ABERDEEN,ROSHOLT SD 49 204 108
9 TIMBER LAKE SD 48 426 499
10 EDGEMONT SD 41 398 750
11 ABERDEEN,DELMONT SD 39 268 205
12 ROGERSVILLE TN 37 498 22,074
13 SEVIERVILLE TN 36 280 41,225
14 OLIVER SPRINGS TN 36 336 5,361
15 CEDAR GROVE,LAVINIA TN 36 288 1,492
16 GERMANTOWN TN 35 552 37,738
17 ABERDEEN,SCOTLAND SD 33 186 150
18 ABERDEEN,FRANKFORT SD 32 176 283
19 FRANKLIN,FRANKLIN PIKE TN 32 264 77,222
20 PIEDMONT,RAPID CITY SD 31 342 1,422
21 ROSHOLT SD 29 274 379
22 ELK POINT SD 28 120 2,124
23 ABERDEEN,HURON SD 28 144 175
24 BERESFORD,WORTHING SD 27 216 5,250
25 PARKER SD 27 108 1,025
26 WAUBAY SD 27 162 473
27 ARLINGTON,RAMONA SD 27 182 159
28 BYRDSTOWN TN 26 306 8,428
29 WOONSOCKET SD 25 104 618
30 ETOWAH,TELLICO PLAINS TN 25 360 7,759
31 MIDDLETON TN 24 196 1,535
32 NEW TAZEWELL TN 23 182 16,135
33 ETOWAH,MADISONVILLE TN 23 184 259
34 HAMILL,WINNER SD 22 270 4,860
35 COLOME SD 22 94 323
36 ABERDEEN,FLANDREAU SD 22 106 107
37 CLARK,FLORENCE SD 21 210 2,927
38 DE SMET SD 21 84 1,056
39 BLACK HAWK,LEAD SD 21 84 448
40 HOHENWALD TN 21 168 12,475
41 MCLEMORESVILLE TN 21 168 376
42 LAKE CITY TN 17 284 27,663
43 DAYTON TN 16 144 25,204
44 HENNING TN 15 74 4,323
45 GAINESBORO TN 15 92 1,596
46 Houston TX 15 13,053 5,913,001
47 Austin TX 15 12,912 1,788,805
48 Des Peres TX 15 12,153 30,946
49 Fresno CA 14 903 630,234
50 KNOXVILLE TN 13 166 573,653

Key Takeaways

  • More contaminant types can indicate multiple pollution sources — agricultural, industrial, and naturally occurring.
  • Cities with more water systems drawing from different sources may detect a wider range of contaminants.
  • Detection of a contaminant means it exceeded the EPA limit at some point, not necessarily that it remains elevated.

Methodology

Data is sourced from the EPA Safe Drinking Water Information System (SDWIS) via the Envirofacts API. Rankings include community water systems serving 100 or more people. Violation counts reflect historical records in the SDWIS database and include both resolved and unresolved violations. Health-based violations include Maximum Contaminant Level (MCL) violations and Treatment Technique violations. Per-capita calculations use the total population served by tracked water systems in each state.

Verify data at epa.gov