2026 Rankings

ZIP Codes with Most EPA Violations in Iowa — 2026

Last updated: June 4, 2026

479 ZIP codes ranked by Violations #1: ZIP 52310 (Monticello, IA) — 119
Lead Violations Lowest Score Safest Flood Risk Energy Cost Radon PFAS Reliability EJ Index Homebuyer Risk CO & Gas Safest Gas Remediation Burden Unresolved Violations (by Utility) Water Equity (by Utility)

Out of 479 ZIP codes with data in Iowa, these are the highest-ranked areas for violations. See also: National ZIP Codes with Most EPA Water Violations | All Iowa Rankings

Statistic Value
ZIP codes ranked 479
Highest value 119
Median value 3
State Iowa

Top 100 Worst ZIP Codes

Rank ZIP Code City State Violations Safety Score
1 52310 Monticello IA 119 64/100
2 52401 Cedar Rapids IA 77 55/100
3 52402 Cedar Rapids IA 77 60/100
4 52403 Cedar Rapids IA 77 55/100
5 52404 Cedar Rapids IA 77 50/100
6 52405 Cedar Rapids IA 77 50/100
7 52406 Cedar Rapids IA 77 65/100
8 52407 Cedar Rapids IA 77 60/100
9 52408 Cedar Rapids IA 77 65/100
10 52409 Cedar Rapids IA 77 60/100
11 52410 Cedar Rapids IA 77 60/100
12 52411 Cedar Rapids IA 77 65/100
13 52497 Cedar Rapids IA 77 60/100
14 52498 Cedar Rapids IA 77 60/100
15 52499 Cedar Rapids IA 77 60/100
16 52341 Toddville IA 55 66/100
17 50501 Fort Dodge IA 27 35/100
18 50112 Grinnell IA 24 36/100
19 50158 Marshalltown IA 24 47/100
20 52322 Oxford IA 22 55/100
21 51555 Missouri Valley IA 21 46/100
22 52208 Belle Plaine IA 21 44/100
23 52722 Bettendorf IA 17 43/100
24 51440 Dedham IA 15 50/100
25 52240 Iowa City IA 14 46/100
26 52242 Iowa City IA 14 51/100
27 52243 Iowa City IA 14 50/100
28 52244 Iowa City IA 14 50/100
29 52245 Iowa City IA 14 51/100
30 52246 Iowa City IA 14 46/100
31 52251 Ladora IA 14 42/100
32 50562 Mallard IA 12 46/100
33 52338 Swisher IA 12 65/100
34 52351 Walford IA 12 61/100
35 50002 Adair IA 11 56/100
36 50853 Massena IA 11 60/100
37 52233 Hiawatha IA 11 62/100
38 52345 Urbana IA 11 62/100
39 51531 Elk Horn IA 10 61/100
40 52213 Center Point IA 10 62/100
41 52801 Davenport IA 10 49/100
42 52802 Davenport IA 10 44/100
43 52803 Davenport IA 10 44/100
44 52804 Davenport IA 10 54/100
45 52805 Davenport IA 10 59/100
46 52806 Davenport IA 10 49/100
47 52807 Davenport IA 10 49/100
48 52808 Davenport IA 10 59/100
49 52809 Davenport IA 10 59/100
50 50126 Iowa Falls IA 9 56/100
51 50140 Lamoni IA 9 65/100
52 51451 Lanesboro IA 9 50/100
53 51540 Hastings IA 9 47/100
54 51559 Neola IA 9 59/100
55 52301 Marengo IA 9 50/100
56 52761 Muscatine IA 9 54/100
57 50128 Jamaica IA 8 32/100
58 50274 Wiota IA 8 59/100
59 50845 Diagonal IA 8 59/100
60 50003 Adel IA 7 59/100
61 50066 Dawson IA 7 45/100
62 50456 Manly IA 7 58/100
63 51527 Defiance IA 7 63/100
64 52533 Batavia IA 7 60/100
65 52637 Mediapolis IA 7 67/100
66 50069 De Soto IA 6 60/100
67 50144 Leon IA 6 60/100
68 50168 Mingo IA 6 62/100
69 50208 Newton IA 6 66/100
70 50301 Des Moines IA 6 62/100
71 50302 Des Moines IA 6 62/100
72 50303 Des Moines IA 6 62/100
73 50304 Des Moines IA 6 62/100
74 50305 Des Moines IA 6 62/100
75 50306 Des Moines IA 6 62/100
76 50307 Des Moines IA 6 62/100
77 50308 Des Moines IA 6 62/100
78 50309 Des Moines IA 6 61/100
79 50310 Des Moines IA 6 61/100
80 50311 Des Moines IA 6 61/100
81 50312 Des Moines IA 6 51/100
82 50313 Des Moines IA 6 56/100
83 50314 Des Moines IA 6 61/100
84 50315 Des Moines IA 6 61/100
85 50316 Des Moines IA 6 61/100
86 50317 Des Moines IA 6 56/100
87 50318 Des Moines IA 6 62/100
88 50319 Des Moines IA 6 62/100
89 50320 Des Moines IA 6 66/100
90 50321 Des Moines IA 6 61/100
91 50328 Des Moines IA 6 62/100
92 50329 Des Moines IA 6 62/100
93 50330 Des Moines IA 6 62/100
94 50331 Des Moines IA 6 62/100
95 50332 Des Moines IA 6 62/100
96 50333 Des Moines IA 6 62/100
97 50334 Des Moines IA 6 62/100
98 50335 Des Moines IA 6 62/100
99 50336 Des Moines IA 6 62/100
100 50339 Des Moines IA 6 62/100

Methodology

Violation counts include all types recorded in the EPA SDWIS database: Maximum Contaminant Level (MCL) violations, treatment technique violations, and monitoring/reporting violations. Both resolved and unresolved violations are counted. Higher counts may reflect longer system histories or larger service areas.

Data sources: EPA Safe Drinking Water Information System (SDWIS), FEMA National Flood Insurance Program, EPA radon zone maps, EIA electricity rates, and Consumer Confidence Reports. Last updated: 2026-06-04.

Frequently Asked Questions

What counts as an EPA water violation?

EPA violations include exceeding Maximum Contaminant Levels (MCLs), failing to treat water properly (treatment technique violations), and not testing or reporting on schedule (monitoring violations). Health-based violations are the most serious.

Does a high violation count mean the water is unsafe now?

Not necessarily. Many violations are historical or monitoring-related. However, a pattern of repeated violations indicates systemic issues with water system management or infrastructure.

Explore More Rankings

How this ranking is calculated, data sources, and limitations: Rankings Methodology →

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Disclaimer: Rankings are based on EPA, FEMA, and federal agency data. They reflect historical patterns and risk indicators, not necessarily current conditions. For the most current information, contact your local water utility or request a Consumer Confidence Report.

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