ZIP Codes with Most EPA Violations in Maryland

Out of 251 ZIP codes with data in Maryland, these are the highest-ranked areas for recorded epa violations. See also: National ZIP Codes with Most EPA Water Violations | All Maryland Rankings

Statistic	Value
ZIP codes ranked	251
Highest value	54
Median value	4
State	Maryland

Top 100 Worst ZIP Codes

Rank	ZIP Code	City	State	Recorded EPA Violations	Safety Score
1	21903	Perryville	MD	54	67/100
2	21902	Perry Point	MD	39	—
3	21078	Havre De Grace	MD	22	59/100
4	20653	Lexington Park	MD	19	—
5	21921	Elkton	MD	19	58/100
6	21227	Halethorpe	MD	18	60/100
7	21229	Baltimore	MD	18	60/100
8	20850	Rockville	MD	16	61/100
9	20851	Rockville	MD	16	61/100
10	20852	Rockville	MD	16	61/100
11	20853	Rockville	MD	16	61/100
12	20854	Potomac	MD	16	61/100
13	20855	Derwood	MD	16	61/100
14	21901	North East	MD	16	77/100
15	21911	Rising Sun	MD	14	—
16	20650	Leonardtown	MD	13	—
17	21210	Baltimore	MD	13	62/100
18	21211	Baltimore	MD	13	62/100
19	21562	Westernport	MD	13	—
20	20619	California	MD	12	—
21	21087	Kingsville	MD	12	63/100
22	20636	Hollywood	MD	11	—
23	20646	La Plata	MD	11	81/100
24	20659	Mechanicsville	MD	11	—
25	21225	Brooklyn	MD	11	—
26	21226	Curtis Bay	MD	11	—
27	21904	Port Deposit	MD	11	—
28	21043	Ellicott City	MD	10	63/100
29	21163	Woodstock	MD	10	63/100
30	20634	Great Mills	MD	9	—
31	21030	Cockeysville	MD	9	64/100
32	21031	Hunt Valley	MD	9	64/100
33	21052	Fort Howard	MD	9	64/100
34	21057	Glen Arm	MD	9	—
35	21071	Glyndon	MD	9	64/100
36	21093	Lutherville Timonium	MD	9	—
37	21111	Monkton	MD	9	—
38	21117	Owings Mills	MD	9	64/100
39	21128	Perry Hall	MD	9	64/100
40	21131	Phoenix	MD	9	64/100
41	21133	Randallstown	MD	9	64/100
42	21136	Reisterstown	MD	9	64/100
43	21152	Sparks Glencoe	MD	9	—
44	21153	Stevenson	MD	9	—
45	21162	White Marsh	MD	9	64/100
46	21201	Baltimore	MD	9	64/100
47	21202	Baltimore	MD	9	64/100
48	21204	Towson	MD	9	64/100
49	21205	Baltimore	MD	9	64/100
50	21206	Baltimore	MD	9	64/100
51	21207	Gwynn Oak	MD	9	64/100
52	21208	Pikesville	MD	9	64/100
53	21209	Baltimore	MD	9	64/100
54	21212	Baltimore	MD	9	64/100
55	21213	Baltimore	MD	9	64/100
56	21214	Baltimore	MD	9	64/100
57	21215	Baltimore	MD	9	64/100
58	21216	Baltimore	MD	9	64/100
59	21217	Baltimore	MD	9	64/100
60	21218	Baltimore	MD	9	64/100
61	21219	Sparrows Point	MD	9	64/100
62	21220	Middle River	MD	9	64/100
63	21221	Essex	MD	9	64/100
64	21222	Dundalk	MD	9	64/100
65	21223	Baltimore	MD	9	64/100
66	21224	Baltimore	MD	9	64/100
67	21228	Catonsville	MD	9	64/100
68	21230	Baltimore	MD	9	64/100
69	21231	Baltimore	MD	9	64/100
70	21233	Baltimore	MD	9	64/100
71	21234	Parkville	MD	9	64/100
72	21236	Nottingham	MD	9	64/100
73	21237	Rosedale	MD	9	64/100
74	21239	Baltimore	MD	9	64/100
75	21244	Windsor Mill	MD	9	64/100
76	21250	Baltimore	MD	9	64/100
77	21251	Baltimore	MD	9	64/100
78	21252	Towson	MD	9	—
79	21285	Baltimore	MD	9	—
80	21286	Towson	MD	9	64/100
81	21287	Baltimore	MD	9	64/100
82	21658	Queenstown	MD	9	—
83	21521	Barton	MD	8	—
84	21532	Frostburg	MD	8	—
85	21539	Lonaconing	MD	8	—
86	21543	Midlothian	MD	8	—
87	21632	Federalsburg	MD	8	—
88	21654	Oxford	MD	8	—
89	21673	Trappe	MD	8	—
90	21784	Sykesville	MD	8	63/100
91	21793	Walkersville	MD	8	64/100
92	21849	Parsonsburg	MD	8	—
93	21850	Pittsville	MD	8	—
94	21874	Willards	MD	8	—
95	20670	Patuxent River	MD	7	—
96	20794	Jessup	MD	7	63/100
97	21076	Hanover	MD	7	80/100
98	21617	Centreville	MD	7	—
99	21740	Hagerstown	MD	7	64/100
100	21757	Keymar	MD	7	—

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: 2026-08-31.

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.

ZIP Codes with Most EPA Violations in Maryland — 2026

Top 100 Worst ZIP Codes

Methodology

Frequently Asked Questions

What counts as an EPA water violation?

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

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