STATE REPORT MD HEALTH VIOLATIONS: 58

Maryland Home Safety Profiles by ZIP

615 ZIP codes · 186 water systems · IPC plumbing code

Data: ZipCheckup Home Safety Score model 4.0.0; EPA SDWIS, UCMR 5, EPA radon zones, EPA AirData, NWS, State plumbing boards, Rewiring America

ZipCheckup tracks drinking-water and home-safety data for 615 ZIP codes across Maryland, covering 186 public water systems that serve about 5,312,670 people. 251 ZIP codes are mapped to at least one water system with an EPA violation on record.

615
ZIP Codes
186
Water Systems
251
ZIPs with Violations
IPC
Plumbing Code
C · 69
Avg Safety Score
2
ZIPs Mapped to a System Above the Lead Action Level
45%
EPA Radon Zone 1 (county-level potential)
#31
of 50 States
29%
ZIPs Rated A or B
70%
ZIPs with Violations
C
Maryland average: 69/100 - ranked #31 of 50 states. 4 points below the national average (73). Water systems mapped to 70% of ZIP codes have recorded violations.

State averages can hide local differences, and the lower average for Maryland is a summary, not a finding about any single ZIP code or water system; the reports for individual ZIP codes, cities and water systems show what the average leaves out.

Score Distribution

How Maryland's 615 ZIP codes are distributed across safety grades.

2
A
59
B
128
C
18
D
0
F
85-10070-8455-6940-540-39

Home Safety Scores by State

Loading map…
F (0-39) D (40-54) C (55-69) B (70-84) A (85+)

Model 4.0.0 inputs: EPA SDWIS, UCMR5 PFAS, EPA radon zones, annual county AQI •

Top 10 ZIP Codes by Home Safety Score in Maryland

Highest Home Safety Scores in the state.

#ZIP CodeCityCountyScoreGrade
1 21613 CambridgeDorchester 100 A
2 21620 ChestertownKent 99 A
3 20601 WaldorfCharles 83 B
4 20602 WaldorfCharles 83 B
5 20603 WaldorfCharles 83 B
6 20616 Bryans RoadCharles 83 B
7 20622 Charlotte HallCharles 83 B
8 20623 CheltenhamPrince George's 83 B
9 20640 Indian HeadCharles 83 B
10 20695 White PlainsCharles 83 B

10 Lowest-Scoring ZIP Codes in Maryland

#ZIP CodeCityCountyScoreGradeViolations
1 21788 ThurmontFrederick 48 D 5
2 21771 Mount AiryFrederick 48 D 6
3 21042 Ellicott CityHoward 48 D 6
4 21001 AberdeenHarford 48 D 5
5 21769 MiddletownFrederick 49 D 2
6 21703 FrederickFrederick 49 D 2
7 21157 WestminsterCarroll 49 D 2
8 21050 Forest HillHarford 49 D 3
9 21047 FallstonHarford 49 D 3
10 21015 Bel AirFrederick 49 D 3

County Rankings

Water quality breakdown by county. 24 counties with data in Maryland.

Loading county map…
F (0-39) D (40-54) C (55-69) B (70-84) A (85+)

County-level aggregation of measured ZIP Home Safety Scores • EPA SDWIS, UCMR 5 PFAS, EPA radon zones, EPA AirData

CountyAvg ScoreGradeZIPsBest ZIPWorst ZIP
24001 N/A N/A 21 N/A N/A
24003 82 B 44 20724 (83) 21076 (80)
24005 64 C 51 21030 (64) 21227 (60)
24009 66 C 14 20629 (67) 20732 (65)
24011 N/A N/A 14 N/A N/A
24013 52 D 11 21784 (63) 21157 (49)
24015 71 B 18 21914 (82) 21921 (58)
24017 83 B 25 20601 (83) 20646 (81)
24019 100 A 16 21613 (100) 21613 (100)
24021 60 C 32 21755 (67) 21788 (48)
24023 N/A N/A 9 N/A N/A
24025 58 C 20 21009 (66) 21001 (48)
24027 63 C 24 20723 (66) 21042 (48)
24029 99 A 8 21620 (99) 21620 (99)
24031 66 C 78 20812 (67) 20837 (50)
24033 83 B 63 20623 (83) 20720 (82)
24035 N/A N/A 14 N/A N/A
24037 N/A N/A 28 N/A N/A
24039 N/A N/A 11 N/A N/A
24041 N/A N/A 18 N/A N/A
24043 62 C 25 21734 (67) 21756 (50)
24045 N/A N/A 17 N/A N/A
24047 N/A N/A 12 N/A N/A
24510 64 C 42 21201 (64) 21229 (60)

Most Common Contaminants in Maryland

Contaminant / RuleCategoryZIPs AffectedViolationsHealth Risk
Lead Inorganic 129 162 No
Stage 2 DBP Rule Treatment Technique 126 189 Yes
Haloacetic Acids (HAA5) Disinfection Byproducts 111 165 Yes
Stage 1 DBP Rule Treatment Technique 91 167 No
Contaminant 2020 Other 81 154 No
Consumer Confidence Report Rule Reporting 76 95 Yes
Contaminant 2959 Other 70 132 No
Lead and Copper Rule Treatment Technique 64 64 No

Overview

We track multi-source home safety signals for 615 ZIP records across Maryland. Home Safety Score model 4.0.0 is published for 207 scored records; missing required evidence suppresses the score.

The EPA snapshots used for this build directly map water systems to 359 ZIP records, covering 186 community water systems that serve approximately 5,312,670 people.

251 of 359 ZIP codes with a reported violation count in the available EPA record (70%) have recorded EPA violations. 58 health-based violations appear in the available health breakdown.

Plumbing Regulations

Maryland follows the International Plumbing Code (2018 edition).

  • Plumbing code: IPC (2018)
  • Homeowner DIY: Licensed plumber required
  • Water heater permit: Required
  • Annual backflow test: Required

Full Maryland regulations →

Areas with Most Violations

ZIP Code City Home Safety Grade Violations Health-Based System
21903 Perryville C 54 16 Town of Perryville
21902 Perry Point — 39 5 Town of Perryville
21078 Havre De Grace C 22 1 City of Havre De Grace
20653 Lexington Park — 19 3 Lexington Park
21921 Elkton C 19 12 Town of Elkton
21227 Halethorpe C 18 3 City of Baltimore
21229 Baltimore C 18 3 City of Baltimore
20850 Rockville C 16 0 City of Rockville
20851 Rockville C 16 0 City of Rockville
20852 Rockville C 16 0 Washington Suburban Sanitary Commission

Areas with No Violations

ZIP Code City Home Safety Grade System Population
20623 Cheltenham B Washington Suburban Sanitary Commission 1,900,000
20629 Dowell C Solomons 3,811
20688 Solomons C Solomons 3,811
20705 Beltsville B Washington Suburban Sanitary Commission 1,900,000
20706 Lanham B Washington Suburban Sanitary Commission 1,900,000
20707 Laurel B Washington Suburban Sanitary Commission 1,900,000
20708 Laurel B Washington Suburban Sanitary Commission 1,900,000
20710 Bladensburg B Washington Suburban Sanitary Commission 1,900,000
20712 Mount Rainier B Washington Suburban Sanitary Commission 1,900,000
20721 Bowie B Washington Suburban Sanitary Commission 1,900,000

Home Safety Score

Average Home Safety Score for Maryland: C (69/100) across 207 scored of 615 tracked ZIP records.

Model 4.0.0 uses the canonical components water-compliance, pfas-mcl-screen, radon-zone, annual-aqi across 3 required domains. The sections below provide additional context and do not change that score. Missing required evidence suppresses the score, and a favorable result is not a property-level safety certification.

Lead & Copper

  • Average of reported 90th-percentile lead results: 0.0017 mg/L (EPA action level: 0.015 mg/L)
  • 2 of 354 ZIP codes with known status exceed the EPA lead action level

Radon Risk

  • High risk (Zone 1): 277 ZIP codes (45%)
  • Moderate risk (Zone 2): 243 ZIP codes
  • Low risk (Zone 3): 95 ZIP codes

ZIP Code Reports for Maryland

Largest Communities

ZIP Code City Population Safety Grade Violations
21771 Mount Airy 1,986,015 D 6
20601 Waldorf 1,984,296 B 3
20850 Rockville 1,952,000 C 16
20851 Rockville 1,952,000 C 16
20852 Rockville 1,952,000 C 16
20853 Rockville 1,952,000 C 16
20854 Potomac 1,952,000 C 16
20855 Derwood 1,952,000 C 16
20715 Bowie 1,925,000 B 2
20716 Bowie 1,925,000 B 2
20720 Bowie 1,925,000 B 2
20607 Accokeek 1,906,560 B 3
20841 Boyds 1,906,005 C 2
20871 Clarksburg 1,901,553 C 0
20613 Brandywine 1,900,330 B 2
20623 Cheltenham 1,900,000 B 0
20705 Beltsville 1,900,000 B 0
20706 Lanham 1,900,000 B 0
20707 Laurel 1,900,000 B 0
20708 Laurel 1,900,000 B 0

Lowest Published Home Safety Scores

ZIP Code City Score Grade Violations
21001 Aberdeen 48 D 5
21042 Ellicott City 48 D 6
21771 Mount Airy 48 D 6
21788 Thurmont 48 D 5
21005 Aberdeen Proving Ground 49 D 3

Highest Published Home Safety Scores

ZIP Code City Score Grade Violations
21613 Cambridge 100 A 0
21620 Chestertown 99 A 2
20601 Waldorf 83 B 3
20602 Waldorf 83 B 3
20603 Waldorf 83 B 3

All 615 ZIP Codes in Maryland

Data Sources

Reporting periods vary by source. Missing data is shown as unavailable, not as zero.

Largest water systems in Maryland

The 12 largest community water systems in Maryland, out of 186 in our data.

Show all 12 water systems

Systems with the most violations in Maryland

12 systems in Maryland with the most recorded EPA violations.

Frequently Asked Questions

Is the water safe to drink in Maryland?

Maryland has 186 community water systems serving 5,312,670 people across 615 ZIP codes. There are 343 recorded violations among these water systems, including 58 health-based. 251 of 615 ZIP codes are mapped to at least one water system with a recorded violation.

What plumbing code does Maryland follow?

Maryland's listed plumbing code type is IPC as of our last review; local jurisdictions may adopt or amend codes. Plumbing work may require a licensed plumber; check state exemptions and local requirements.

Is lead a concern in Maryland's drinking water?

2 ZIP codes in Maryland are mapped to water systems whose reported 90th-percentile lead result exceeded the EPA action level of 0.015 mg/L.

What is the radon risk in Maryland?

45% of ZIP codes in Maryland are mapped to counties classified as EPA Radon Zone 1 (highest county-level radon potential).

How to cite this page

APA ZipCheckup. (2026). Maryland Home Safety Profiles by ZIP. https://zipcheckup.com/states/maryland/
BibTeX 
@misc{zipcheckup-states-maryland,
  author = {{ZipCheckup}},
  title  = {{Maryland Home Safety Profiles by ZIP}},
  year   = {2026},
  url    = {https://zipcheckup.com/states/maryland/}
}

Page version: October 2026.

Get safety alerts for Maryland

Free updates when EPA data changes for this area. No spam.

Unsubscribe anytime. Privacy Policy.

Share This Page

X Facebook
Violations found - check filter options Free tool - no phone call required.