Least Reliable Water Systems in Maryland — 2026

Out of 630 ZIP codes with data in Maryland, these are the lowest-ranked areas for reliability score. See also: National Least Reliable Water Systems in America | All Maryland Rankings

Statistic	Value
ZIP codes ranked	630
Lowest value	25/100
Median value	77/100
State	Maryland

100 Lowest-Ranked ZIP Codes

Rank	ZIP Code	City	State	Reliability Score	Safety Score
1	21901	North East	MD	25/100	59/100
2	21903	Perryville	MD	35/100	59/100
3	21639	Greensboro	MD	37/100	89/100
4	21917	Colora	MD	39/100	53/100
5	20619	California	MD	40/100	53/100
6	21784	Sykesville	MD	40/100	57/100
7	21645	Kennedyville	MD	42/100	88/100
8	21911	Rising Sun	MD	42/100	74/100
9	21913	Cecilton	MD	44/100	56/100
10	21866	Tylerton	MD	46/100	67/100
11	20658	Marbury	MD	47/100	71/100
12	20794	Jessup	MD	47/100	59/100
13	21041	Ellicott City	MD	47/100	69/100
14	21042	Ellicott City	MD	47/100	59/100
15	21562	Westernport	MD	49/100	63/100
16	20602	Waldorf	MD	50/100	77/100
17	20603	Waldorf	MD	50/100	72/100
18	20604	Waldorf	MD	50/100	77/100
19	20650	Leonardtown	MD	51/100	70/100
20	21619	Chester	MD	54/100	80/100
21	21842	Ocean City	MD	54/100	73/100
22	21843	Ocean City	MD	54/100	93/100
23	20601	Waldorf	MD	55/100	72/100
24	21841	Newark	MD	55/100	90/100
25	21904	Port Deposit	MD	55/100	66/100
26	21078	Havre De Grace	MD	57/100	56/100
27	21771	Mount Airy	MD	57/100	69/100
28	20639	Huntingtown	MD	59/100	50/100
29	21624	Claiborne	MD	59/100	93/100
30	20608	Aquasco	MD	60/100	53/100
31	20615	Broomes Island	MD	60/100	55/100
32	20618	Bushwood	MD	60/100	63/100
33	20643	Ironsides	MD	60/100	53/100
34	20660	Morganza	MD	60/100	53/100
35	20661	Mount Victoria	MD	60/100	53/100
36	20662	Nanjemoy	MD	60/100	63/100
37	20670	Patuxent River	MD	60/100	80/100
38	20678	Prince Frederick	MD	60/100	63/100
39	20682	Rock Point	MD	60/100	53/100
40	20777	Highland	MD	60/100	53/100
41	20838	Barnesville	MD	60/100	66/100
42	21036	Dayton	MD	60/100	40/100
43	21150	Simpsonville	MD	60/100	40/100
44	21522	Bittinger	MD	60/100	53/100
45	21531	Friendsville	MD	60/100	55/100
46	21541	Mc Henry	MD	60/100	63/100
47	21612	Bozman	MD	60/100	65/100
48	21635	Galena	MD	60/100	63/100
49	21647	Mcdaniel	MD	60/100	73/100
50	21661	Rock Hall	MD	60/100	78/100
51	21663	Saint Michaels	MD	60/100	60/100
52	21665	Sherwood	MD	60/100	65/100
53	21671	Tilghman	MD	60/100	60/100
54	21676	Wittman	MD	60/100	65/100
55	21723	Cooksville	MD	60/100	40/100
56	21737	Glenelg	MD	60/100	53/100
57	21738	Glenwood	MD	60/100	53/100
58	21740	Hagerstown	MD	60/100	63/100
59	21741	Hagerstown	MD	60/100	68/100
60	21742	Hagerstown	MD	60/100	58/100
61	21746	Hagerstown	MD	60/100	64/100
62	21747	Hagerstown	MD	60/100	64/100
63	21748	Hagerstown	MD	60/100	64/100
64	21749	Hagerstown	MD	60/100	64/100
65	21811	Berlin	MD	60/100	78/100
66	21930	Georgetown	MD	60/100	63/100
67	20871	Clarksburg	MD	61/100	64/100
68	20664	Newburg	MD	62/100	72/100
69	21157	Westminster	MD	62/100	64/100
70	21158	Westminster	MD	62/100	69/100
71	21632	Federalsburg	MD	64/100	88/100
72	20606	Abell	MD	65/100	63/100
73	20609	Avenue	MD	65/100	55/100
74	20621	Chaptico	MD	65/100	63/100
75	20624	Clements	MD	65/100	53/100
76	20626	Coltons Point	MD	65/100	55/100
77	20627	Compton	MD	65/100	63/100
78	20635	Helen	MD	65/100	53/100
79	20656	Loveville	MD	65/100	53/100
80	20659	Mechanicsville	MD	65/100	55/100
81	20667	Park Hall	MD	65/100	63/100
82	21032	Crownsville	MD	65/100	55/100
83	21035	Davidsonville	MD	65/100	55/100
84	21114	Crofton	MD	65/100	78/100
85	21520	Accident	MD	65/100	82/100
86	21545	Mount Savage	MD	65/100	55/100
87	21658	Queenstown	MD	65/100	76/100
88	21765	Lisbon	MD	65/100	40/100
89	21797	Woodbine	MD	65/100	53/100
90	21798	Woodsboro	MD	65/100	64/100
91	21810	Allen	MD	65/100	63/100
92	21822	Eden	MD	65/100	63/100
93	21872	Whaleyville	MD	65/100	63/100
94	21914	Charlestown	MD	65/100	55/100
95	21920	Elk Mills	MD	65/100	53/100
96	21034	Darlington	MD	66/100	62/100
97	20653	Lexington Park	MD	67/100	77/100
98	20657	Lusby	MD	67/100	51/100
99	21043	Ellicott City	MD	67/100	54/100
100	21629	Denton	MD	67/100	94/100

Methodology

Water system reliability scores (0-100) combine violation frequency, violation recency, resolution rate, and system size. Systems with repeated health-based violations and unresolved issues score lowest. The reliability score focuses specifically on the water utility performance, distinct from the broader Home Safety Score.

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 does a low water reliability score mean?

A low reliability score (below 50) indicates a water system with frequent violations, poor resolution rates, or recurring compliance issues. These systems may have aging infrastructure, inadequate treatment, or management challenges.

How is reliability different from safety score?

The reliability score focuses specifically on the water utility performance (violations, resolution, compliance). The Home Safety Score is broader, also including lead risk, radon, and flood data. A ZIP code can have a reliable water system but still have high radon or flood risk.