Least Reliable Water Systems in Delaware — 2026

Out of 86 ZIP codes with data in Delaware, these are the lowest-ranked areas for reliability score. See also: National Least Reliable Water Systems in America | All Delaware Rankings

Statistic	Value
ZIP codes ranked	86
Lowest value	62/100
Median value	80/100
State	Delaware

86 Lowest-Ranked ZIP Codes

Rank	ZIP Code	City	State	Reliability Score	Safety Score
1	19901	Dover	DE	62/100	80/100
2	19903	Dover	DE	62/100	93/100
3	19904	Dover	DE	62/100	85/100
4	19905	Dover	DE	62/100	93/100
5	19906	Dover	DE	62/100	93/100
6	19941	Ellendale	DE	65/100	94/100
7	19955	Kenton	DE	65/100	98/100
8	19979	Viola	DE	65/100	97/100
9	19950	Greenwood	DE	67/100	89/100
10	19960	Lincoln	DE	67/100	91/100
11	19936	Cheswold	DE	70/100	94/100
12	19943	Felton	DE	70/100	91/100
13	19944	Fenwick Island	DE	70/100	79/100
14	19947	Georgetown	DE	70/100	93/100
15	19956	Laurel	DE	70/100	89/100
16	19958	Lewes	DE	70/100	55/100
17	19961	Little Creek	DE	70/100	94/100
18	19962	Magnolia	DE	70/100	94/100
19	19966	Millsboro	DE	70/100	80/100
20	19973	Seaford	DE	70/100	84/100
21	19975	Selbyville	DE	70/100	79/100
22	19977	Smyrna	DE	70/100	87/100
23	19707	Hockessin	DE	73/100	72/100
24	19709	Middletown	DE	73/100	73/100
25	19710	Montchanin	DE	73/100	75/100
26	19940	Delmar	DE	73/100	95/100
27	19953	Hartly	DE	73/100	95/100
28	19968	Milton	DE	73/100	80/100
29	19731	Port Penn	DE	75/100	83/100
30	19732	Rockland	DE	75/100	55/100
31	19734	Townsend	DE	75/100	83/100
32	19736	Yorklyn	DE	75/100	55/100
33	19934	Camden Wyoming	DE	75/100	73/100
34	19951	Harbeson	DE	75/100	87/100
35	19964	Marydel	DE	75/100	95/100
36	19969	Nassau	DE	75/100	88/100
37	19980	Woodside	DE	75/100	66/100
38	19967	Millville	DE	77/100	94/100
39	19939	Dagsboro	DE	78/100	83/100
40	19952	Harrington	DE	78/100	93/100
41	19970	Ocean View	DE	78/100	84/100
42	19701	Bear	DE	80/100	70/100
43	19706	Delaware City	DE	80/100	78/100
44	19708	Kirkwood	DE	80/100	53/100
45	19720	New Castle	DE	80/100	73/100
46	19721	New Castle	DE	80/100	83/100
47	19730	Odessa	DE	80/100	83/100
48	19733	Saint Georges	DE	80/100	53/100
49	19735	Winterthur	DE	80/100	60/100
50	19902	Dover Afb	DE	80/100	99/100
51	19930	Bethany Beach	DE	80/100	75/100
52	19931	Bethel	DE	80/100	73/100
53	19933	Bridgeville	DE	80/100	95/100
54	19938	Clayton	DE	80/100	87/100
55	19945	Frankford	DE	80/100	90/100
56	19946	Frederica	DE	80/100	85/100
57	19954	Houston	DE	80/100	66/100
58	19963	Milford	DE	80/100	85/100
59	19971	Rehoboth Bch	DE	80/100	55/100
60	19801	Wilmington	DE	93/100	73/100
61	19802	Wilmington	DE	93/100	73/100
62	19803	Wilmington	DE	93/100	73/100
63	19804	Wilmington	DE	93/100	68/100
64	19805	Wilmington	DE	93/100	73/100
65	19806	Wilmington	DE	93/100	78/100
66	19807	Wilmington	DE	93/100	90/100
67	19808	Wilmington	DE	93/100	73/100
68	19809	Wilmington	DE	93/100	78/100
69	19810	Wilmington	DE	93/100	73/100
70	19850	Wilmington	DE	93/100	83/100
71	19880	Wilmington	DE	93/100	83/100
72	19884	Wilmington	DE	93/100	83/100
73	19885	Wilmington	DE	93/100	83/100
74	19886	Wilmington	DE	93/100	83/100
75	19887	Wilmington	DE	93/100	83/100
76	19890	Wilmington	DE	93/100	83/100
77	19891	Wilmington	DE	93/100	83/100
78	19892	Wilmington	DE	93/100	83/100
79	19893	Wilmington	DE	93/100	83/100
80	19894	Wilmington	DE	93/100	83/100
81	19895	Wilmington	DE	93/100	83/100
82	19896	Wilmington	DE	93/100	83/100
83	19897	Wilmington	DE	93/100	83/100
84	19898	Wilmington	DE	93/100	83/100
85	19899	Wilmington	DE	93/100	83/100
86	19703	Claymont	DE	95/100	55/100

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: 2026-04-13.

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.