Maryland — 3rd District
119th Congress · 39 ZIP codes · Avg score 51/100 · Grade D · Updated 2026-06-03
Data: EPA SDWIS / Census 119th Congress Last verified: 2026-06-03
Top Contaminants
ZIP Codes in This District
39 ZIP codes tracked in Maryland's 3rd District.
| # | ZIP Code | City | Safety Score | Grade | Violations |
|---|---|---|---|---|---|
| 1 | 21048 | Finksburg | 70 | B | 0 |
| 2 | 21102 | Manchester | 70 | B | 0 |
| 3 | 21776 | New Windsor | 70 | B | 0 |
| 4 | 21041 | Ellicott City | 69 | C | 11 (1 health) |
| 5 | 21771 | Mount Airy | 69 | C | 14 (1 health) |
| 6 | 21791 | Union Bridge | 67 | C | 0 |
| 7 | 21074 | Hampstead | 65 | C | 0 |
| 8 | 21787 | Taneytown | 65 | C | 0 |
| 9 | 21042 | Ellicott City | 59 | C | 11 (1 health) |
| 10 | 21784 | Sykesville | 57 | C | 8 (5 health) |
| 11 | 21043 | Ellicott City | 54 | D | 11 (1 health) |
| 12 | 20777 | Highland | 53 | D | 0 |
| 13 | 20850 | Rockville | 53 | D | 0 |
| 14 | 21023 | Butler | 53 | D | 0 |
| 15 | 21029 | Clarksville | 53 | D | 0 |
| 16 | 21071 | Glyndon | 53 | D | 0 |
| 17 | 21104 | Marriottsville | 53 | D | 0 |
| 18 | 21136 | Reisterstown | 53 | D | 0 |
| 19 | 21163 | Woodstock | 53 | D | 0 |
| 20 | 21737 | Glenelg | 53 | D | 0 |
| 21 | 21738 | Glenwood | 53 | D | 0 |
| 22 | 21792 | Unionville | 53 | D | 0 |
| 23 | 21797 | Woodbine | 53 | D | 0 |
| 24 | 21666 | Stevensville | 47 | D | 0 |
| 25 | 20847 | Rockville | 40 | D | 0 |
| 26 | 20849 | Rockville | 40 | D | 0 |
| 27 | 20857 | Rockville | 40 | D | 0 |
| 28 | 20883 | Gaithersburg | 40 | D | 0 |
| 29 | 21020 | Boring | 40 | D | 0 |
| 30 | 21036 | Dayton | 40 | D | 0 |
| 31 | 21088 | Lineboro | 40 | D | 0 |
| 32 | 21150 | Simpsonville | 40 | D | 0 |
| 33 | 21155 | Upperco | 40 | D | 0 |
| 34 | 21723 | Cooksville | 40 | D | 0 |
| 35 | 21765 | Lisbon | 40 | D | 0 |
| 36 | 21770 | Monrovia | 40 | D | 0 |
| 37 | 21794 | West Friendship | 40 | D | 0 |
| 38 | 20854 | Potomac | 35 | F | 0 |
| 39 | 20859 | Potomac | 33 | F | 0 |
Overview
Maryland's 3rd District serving an estimated 102,927 residents encompasses 39 ZIP codes tracked by ZipCheckup. The district's average Home Safety Score is D (51/100).
55 EPA violations have been recorded across this district's water systems. 9 are health-based violations. About 13% of tracked ZIP codes have at least one violation.
Top Contaminants
The most frequently cited water quality issues in this district:
- Stage 2 DBP Rule — 12 violations
- Total Trihalomethanes (TTHM) — 11 violations
- Haloacetic Acids (HAA5) — 10 violations
- Surface Water Treatment Rule — 10 violations
- Nickel — 4 violations
Housing Context
Homes in this district were built on average around 1984 (~42 years old). Older homes may have lead pipes or solder — consider a water filter if your home predates 1986.
Lead Alert: 2 ZIP codes in this district exceed the EPA action level for lead. Consider using a certified lead-removal filter.
Data Sources
- Water quality violations: EPA Safe Drinking Water Information System (SDWIS)
- Congressional district boundaries: U.S. Census Bureau, 119th Congress
- Housing age: U.S. Census Bureau American Community Survey
Updated daily. Data covers 39 ZIP codes in Maryland's 3rd District.