Data: EPA SDWIS, NWS, State plumbing boards, Rewiring America Last verified: 2026-06-03

Residents across Delaware generally have access to tap water that meets federal safety benchmarks.

Score Distribution

How Delaware's 97 ZIP codes are distributed across safety grades.

Top 10 Safest ZIP Codes in Delaware

Highest Home Safety Scores in the state.

10 Lowest-Scoring ZIP Codes in Delaware

County Rankings

Water quality breakdown by county. 3 counties with data in Delaware.

Most Common Contaminants in Delaware

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Overview

We track water quality, weather alerts, plumbing regulations, and energy rebates for 97 ZIP codes across Delaware, covering 140 community water systems that serve approximately 816,513 people.

66 of 97 ZIP codes (68%) have recorded EPA violations. 14 health-based violations have been documented.

Plumbing Regulations

Delaware follows the International Plumbing Code (2021 edition).

• Plumbing code: IPC (2021)
• Homeowner DIY: Licensed plumber required
• Water heater permit: Required
• Annual backflow test: Required

Full Delaware regulations →

Areas with Most Violations

Areas with No Violations

Home Safety Score

Average Home Safety Score for Delaware: B (81/100)

Lead & Copper

• Average lead level (90th percentile): 0.0023 mg/L (EPA action level: 0.015 mg/L)
• 1 ZIP code exceed the EPA lead action level

Radon Risk

• High risk (Zone 1): 0 ZIP codes (0%)
• Moderate risk (Zone 2): 52 ZIP codes
• Low risk (Zone 3): 45 ZIP codes

ZIP Code Reports for Delaware

Largest Communities

Lowest Safety Scores

Highest Safety Scores

All 97 ZIP Codes in Delaware

• 19701 (Bear) [B]
• 19930 (Bethany Beach) [B]
• 19931 (Bethel) [B]
• 19933 (Bridgeville) [A]
• 19934 (Camden Wyoming) [B]
• 19936 (Cheswold) [A] — 2 violations
• 19703 (Claymont) [C]
• 19938 (Clayton) [A]
• 19939 (Dagsboro) [B] — 1 violation
• 19706 (Delaware City) [B]
• 19940 (Delmar) [A]
• 19901 (Dover) [B] — 3 violations ⚠
• 19903 (Dover) [A] — 3 violations ⚠
• 19904 (Dover) [A] — 3 violations ⚠
• 19905 (Dover) [A] — 3 violations ⚠
• 19906 (Dover) [A] — 3 violations ⚠
• 19902 (Dover Afb) [A]
• 19941 (Ellendale) [A] — 2 violations
• 19943 (Felton) [A] — 1 violation
• 19944 (Fenwick Island) [B] — 3 violations
• 19945 (Frankford) [A]
• 19946 (Frederica) [A]
• 19947 (Georgetown) [A] — 4 violations
• 19950 (Greenwood) [A] — 3 violations ⚠
• 19951 (Harbeson) [A]
• 19952 (Harrington) [A] — 4 violations
• 19953 (Hartly) [A] — 1 violation
• 19707 (Hockessin) [B] — 2 violations
• 19954 (Houston) [C]
• 19955 (Kenton) [A] — 2 violations
• 19708 (Kirkwood) [D]
• 19956 (Laurel) [A] — 2 violations
• 19958 (Lewes) [C] — 1 violation
• 19960 (Lincoln) [A] — 3 violations ⚠
• 19961 (Little Creek) [A] — 2 violations ⚠
• 19962 (Magnolia) [A] — 2 violations
• 19964 (Marydel) [A]
• 19709 (Middletown) [B]
• 19963 (Milford) [A]
• 19966 (Millsboro) [B] — 1 violation
• 19967 (Millville) [A] — 3 violations ⚠
• 19968 (Milton) [B]
• 19710 (Montchanin) [B] — 2 violations
• 19969 (Nassau) [A]
• 19720 (New Castle) [B]
• 19721 (New Castle) [B]
• 19702 (Newark) [B] — 5 violations
• 19711 (Newark) [B] — 5 violations
• 19712 (Newark) [B] — 5 violations
• 19713 (Newark) [B] — 5 violations
• 19714 (Newark) [B] — 5 violations
• 19715 (Newark) [B] — 5 violations
• 19716 (Newark) [B] — 5 violations
• 19717 (Newark) [B] — 5 violations
• 19718 (Newark) [B] — 5 violations
• 19725 (Newark) [B] — 5 violations
• 19726 (Newark) [B] — 5 violations
• 19970 (Ocean View) [B] — 2 violations
• 19730 (Odessa) [B]
• 19731 (Port Penn) [B]
• 19971 (Rehoboth Bch) [C]
• 19732 (Rockland) [C]
• 19733 (Saint Georges) [D]
• 19973 (Seaford) [B] — 2 violations
• 19975 (Selbyville) [B] — 3 violations
• 19977 (Smyrna) [A] — 7 violations
• 19734 (Townsend) [B]
• 19979 (Viola) [A] — 4 violations
• 19801 (Wilmington) [B] — 1 violation
• 19802 (Wilmington) [B] — 1 violation
• 19803 (Wilmington) [B] — 1 violation
• 19804 (Wilmington) [C] — 1 violation
• 19805 (Wilmington) [B] — 1 violation
• 19806 (Wilmington) [B] — 1 violation
• 19807 (Wilmington) [A] — 1 violation
• 19808 (Wilmington) [B] — 1 violation
• 19809 (Wilmington) [B] — 1 violation
• 19810 (Wilmington) [B] — 1 violation
• 19850 (Wilmington) [B] — 1 violation
• 19880 (Wilmington) [B] — 1 violation
• 19884 (Wilmington) [B] — 1 violation
• 19885 (Wilmington) [B] — 1 violation
• 19886 (Wilmington) [B] — 1 violation
• 19887 (Wilmington) [B] — 1 violation
• 19890 (Wilmington) [B] — 1 violation
• 19891 (Wilmington) [B] — 1 violation
• 19892 (Wilmington) [B] — 1 violation
• 19893 (Wilmington) [B] — 1 violation
• 19894 (Wilmington) [B] — 1 violation
• 19895 (Wilmington) [B] — 1 violation
• 19896 (Wilmington) [B] — 1 violation
• 19897 (Wilmington) [B] — 1 violation
• 19898 (Wilmington) [B] — 1 violation
• 19899 (Wilmington) [B] — 1 violation
• 19735 (Winterthur) [C]
• 19980 (Woodside) [C]
• 19736 (Yorklyn) [C]

Data Sources

• Water quality: EPA Safe Drinking Water Information System (SDWIS)
• Regulations: State plumbing boards, ICC, IAPMO

Updated daily.

Frequently Asked Questions

Is the water safe to drink in Delaware?

Delaware has 140 community water systems serving 816,513 people across 97 ZIP codes. There are 155 recorded violations, including 14 health-based. 66 of 97 ZIP codes have at least one violation.

What plumbing code does Delaware follow?

Delaware follows the IPC plumbing code. A licensed plumber is generally required for plumbing work.

Is lead a concern in Delaware's drinking water?

1 ZIP code in Delaware has lead levels exceeding the EPA action level of 0.015 mg/L.