Montgomery County, Maryland
65 ZIP codes · Avg score 52/100 · Grade D · Updated 2026-06-03
Montgomery County's 65 ZIP codes show a poor compliance record — repeated MCL exceedances have kept the county in the bottom tier for water safety.
How Montgomery County Compares
How Montgomery County Compares
Montgomery County scores 9 points below the Maryland state average (61/100) and 16 points below the national average (68/100).
Data: EPA SDWIS Last verified: 2026-06-03
ZIP Code Risk Map
Water Quality Map: Montgomery County, Maryland
Each dot represents a ZIP code. Color indicates water quality grade. Tap a dot for details.
Key Risk Factors
Health risk index: 10.9 (asthma 9.8%, diabetes 11.9%)
Estimated additional annual cost per homeowner: $2,504, driven primarily by sea_level
Infrastructure: 0.372% avg pipe failure probability, 41% of ZIPs at high risk
68.2% of homes built before 1978 (lead paint era)
Violation History (2023–2024)
→ Stable trendEPA violation counts by year across Montgomery County water systems. Health-based shown in red, total in blue.
Peak year: 2023 with 2 violations. Past 5 years: 3 total (3 health-based).
Source: EPA SDWIS historical violations. Data may lag 6–12 months for the most recent year.
County Health Indicators vs National Average
Black markers indicate national averages. Source: CDC PLACES, Census ACS.
Infrastructure Overview
Sources: Census ACS (housing age), EPA SDWIS (infrastructure risk model), state bridge inspection data.
Compound Risk Breakdown
Estimated additional annual cost per homeowner: $2,504
Bar widths proportional to share of total annual risk cost. Source: compound risk model (FEMA, EPA, USGS).
Housing Age Distribution
322,127 housing units in Montgomery County
Source: U.S. Census Bureau ACS B25034 (Year Structure Built).
Water Safety Affordability
How much it costs to fix water issues relative to home values in Montgomery County
Remediation costs are relatively manageable for most homeowners in Montgomery County, representing a small fraction of property value.
Remediation includes water filtration, lead abatement, radon mitigation, and flood protection where applicable. Source: Census ACS, EPA SDWIS.
Health Outcomes vs National Average
CDC PLACES data for Montgomery County residents
Black markers = national averages. Red = above national avg. Green = below. Source: CDC PLACES, Census ACS.
Water Systems with Most Violations
Top 5 systems in Montgomery County ranked by EPA violation count.
| # | Water System | Population | Violations |
|---|---|---|---|
| 1 | WASHINGTON SUBURBAN SANITARY COMMISSION | 1,900,000 | 7 |
| 2 | Knolls of Windsor | 1,553 | 7 |
| 3 | Country Village Mobile Home Park | 38 | 7 |
| 4 | Town of Poolesville | 6,005 | 2 |
| 5 | FAIRLAND CROSSING APARTMENTS | 1,248 | 0 |
10 total water systems serve Montgomery County.
All ZIP Codes in Montgomery County
65 ZIP codes tracked in Montgomery County.
| # | ZIP Code | City | Safety Score | Grade | Violations | Home Value |
|---|---|---|---|---|---|---|
| 1 | 20837 | Poolesville | 68 | C | 2 | $701K |
| 2 | 20810 | Bethesda | 66 | C | 0 | — |
| 3 | 20811 | Bethesda | 66 | C | 0 | — |
| 4 | 20813 | Bethesda | 66 | C | 0 | — |
| 5 | 20824 | Bethesda | 66 | C | 0 | — |
| 6 | 20827 | Bethesda | 66 | C | 0 | — |
| 7 | 20889 | Bethesda | 66 | C | 0 | — |
| 8 | 20892 | Bethesda | 66 | C | 0 | — |
| 9 | 20894 | Bethesda | 66 | C | 0 | — |
| 10 | 20814 | Bethesda | 65 | C | 0 | $977K |
| 11 | 20816 | Bethesda | 65 | C | 0 | $1166K |
| 12 | 20871 | Clarksburg | 64 | C | 7 (3 health) | $629K |
| 13 | 20903 | Silver Spring | 62 | C | 0 | $468K |
| 14 | 20905 | Silver Spring | 62 | C | 0 | $640K |
| 15 | 20817 | Bethesda | 60 | C | 0 | $1142K |
| 16 | 20901 | Silver Spring | 57 | C | 0 | $571K |
| 17 | 20904 | Silver Spring | 57 | C | 0 | $534K |
| 18 | 20910 | Silver Spring | 57 | C | 0 | $691K |
| 19 | 20907 | Silver Spring | 55 | C | 0 | — |
| 20 | 20908 | Silver Spring | 55 | C | 0 | — |
| 21 | 20911 | Silver Spring | 55 | C | 0 | — |
| 22 | 20914 | Silver Spring | 55 | C | 0 | — |
| 23 | 20915 | Silver Spring | 55 | C | 0 | — |
| 24 | 20916 | Silver Spring | 55 | C | 0 | — |
| 25 | 20918 | Silver Spring | 55 | C | 0 | — |
| 26 | 20993 | Silver Spring | 55 | C | 0 | — |
| 27 | 20997 | Silver Spring | 55 | C | 0 | — |
| 28 | 20710 | Bladensburg | 53 | D | 0 | $335K |
| 29 | 20712 | Mount Rainier | 53 | D | 0 | $531K |
| 30 | 20759 | Fulton | 53 | D | 0 | $888K |
| 31 | 20763 | Savage | 53 | D | 0 | $406K |
| 32 | 20770 | Greenbelt | 53 | D | 0 | $249K |
| 33 | 20832 | Olney | 53 | D | 0 | $601K |
| 34 | 20833 | Brookeville | 53 | D | 0 | $762K |
| 35 | 20851 | Rockville | 53 | D | 0 | $524K |
| 36 | 20860 | Sandy Spring | 53 | D | 0 | $665K |
| 37 | 20861 | Ashton | 53 | D | 0 | $956K |
| 38 | 20866 | Burtonsville | 53 | D | 0 | $434K |
| 39 | 20912 | Takoma Park | 53 | D | 0 | $671K |
| 40 | 20902 | Silver Spring | 52 | D | 0 | $531K |
| 41 | 20906 | Silver Spring | 52 | D | 0 | $441K |
| 42 | 20705 | Beltsville | 45 | D | 0 | $423K |
| 43 | 20722 | Brentwood | 45 | D | 0 | $379K |
| 44 | 20740 | College Park | 45 | D | 0 | $417K |
| 45 | 20781 | Hyattsville | 45 | D | 0 | $453K |
| 46 | 20783 | Hyattsville | 45 | D | 0 | $400K |
| 47 | 20842 | Dickerson | 45 | D | 0 | $709K |
| 48 | 20853 | Rockville | 45 | D | 0 | $606K |
| 49 | 20895 | Kensington | 45 | D | 0 | $744K |
| 50 | 20704 | Beltsville | 40 | D | 0 | — |
| 51 | 20737 | Riverdale | 40 | D | 0 | $370K |
| 52 | 20742 | College Park | 40 | D | 0 | — |
| 53 | 20768 | Greenbelt | 40 | D | 0 | — |
| 54 | 20771 | Greenbelt | 40 | D | 0 | — |
| 55 | 20782 | Hyattsville | 40 | D | 0 | $431K |
| 56 | 20787 | Hyattsville | 40 | D | 0 | — |
| 57 | 20788 | Hyattsville | 40 | D | 0 | — |
| 58 | 20830 | Olney | 40 | D | 0 | — |
| 59 | 20839 | Beallsville | 40 | D | 0 | $900K |
| 60 | 20862 | Brinklow | 40 | D | 0 | $804K |
| 61 | 20868 | Spencerville | 40 | D | 0 | $565K |
| 62 | 20891 | Kensington | 40 | D | 0 | — |
| 63 | 20913 | Takoma Park | 40 | D | 0 | — |
| 64 | 20854 | Potomac | 35 | F | 0 | $1105K |
| 65 | 20859 | Potomac | 33 | F | 0 | — |
Recommended Buyer Guides for Montgomery County
Retailer arrangements don't shape what appears here — the selection logic is independent, filtered against EPA detections and the federal hazard data on file for this county.
- Best Water Filters for Lead — Lead above EPA action level in 2 ZIP codes
- Best Lead Paint Test Kits — 68.2% of homes built before 1978
- Best Under-Sink Reverse Osmosis Systems — Multi-contaminant removal at the kitchen tap
- Best Radon Test Kits — EPA Radon Zone 1 (highest risk) dominant in county
Deep Dive Reports
Detailed analysis for Montgomery County, Maryland
Overview
Montgomery County in Maryland covers 65 ZIP codes with an average Home Safety Score of D (52/100).
2 of 65 ZIP codes have recorded EPA violations. 3 health-based violations have been documented.
← Back to Maryland water quality report
Data Sources
- Water quality: EPA Safe Drinking Water Information System (SDWIS)
- Home values: U.S. Census Bureau ACS (median estimates by ZCTA)
Updated daily.
What You Can Do
Montgomery County has a grade of D. Here are steps to protect your household.
Test your tap water
Order a certified lab test kit ($20-$50) to check for lead, bacteria, and other contaminants specific to your ZIP code.
Consider a certified water filter
NSF-certified filters can remove most common contaminants. Match the filter to your test results for best protection. Try our filter matcher
Contact your water utility
Request the latest Consumer Confidence Report (CCR) from your water provider. It details exactly what was found in your water supply.
Check for lead in your home
68.2% of homes in this county were built before 1978. Older plumbing and solder can leach lead into drinking water, especially in the morning.