Loudoun County, Virginia
33 ZIP codes · Avg score 71/100 · Grade B · Updated 2026-06-03
In recent assessments, Loudoun County's 33 ZIP codes record strong, consistent water safety outcomes.
How Loudoun County Compares
How Loudoun County Compares
Loudoun County scores 5 points above the Virginia state average (66/100) and 3 points above the national average (68/100).
Data: EPA SDWIS Last verified: 2026-06-03
ZIP Code Risk Map
Water Quality Map: Loudoun County, Virginia
Each dot represents a ZIP code. Color indicates water quality grade. Tap a dot for details.
Key Risk Factors
Health risk index: 10 (asthma 9%, diabetes 9.7%)
Estimated additional annual cost per homeowner: $1,797, driven primarily by sea_level
Infrastructure: 0.267% avg pipe failure probability, 5% of ZIPs at high risk
Violation History (2024–2025)
→ Stable trendEPA violation counts by year across Loudoun County water systems. Health-based shown in red, total in blue.
Peak year: 2025 with 10 violations. Past 5 years: 15 total (15 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: $1,797
Bar widths proportional to share of total annual risk cost. Source: compound risk model (FEMA, EPA, USGS).
Water Safety Affordability
How much it costs to fix water issues relative to home values in Loudoun County
Remediation costs are relatively manageable for most homeowners in Loudoun 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 Loudoun 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 Loudoun County ranked by EPA violation count.
| # | Water System | Population | Violations |
|---|---|---|---|
| 1 | LOUDOUN WATER - CENTRAL SYSTEM | 334,808 | 6 |
| 2 | Foxcroft School | 301 | 4 |
| 3 | Middleburg, Town of | 803 | 3 |
| 4 | ROUND HILL, TOWN OF | 5,019 | 2 |
| 5 | HAMILTON, TOWN OF | 2,240 | 2 |
17 total water systems serve Loudoun County.
All ZIP Codes in Loudoun County
33 ZIP codes tracked in Loudoun County.
| # | ZIP Code | City | Safety Score | Grade | Violations | Home Value |
|---|---|---|---|---|---|---|
| 1 | 20105 | Aldie | 83 | B | 1 | $807K |
| 2 | 20132 | Purcellville | 83 | B | 0 | $704K |
| 3 | 20134 | Purcellville | 83 | B | 0 | — |
| 4 | 20141 | Round Hill | 83 | B | 0 | $677K |
| 5 | 20142 | Round Hill | 83 | B | 0 | — |
| 6 | 20146 | Ashburn | 83 | B | 1 | — |
| 7 | 20147 | Ashburn | 83 | B | 1 | $680K |
| 8 | 20148 | Ashburn | 83 | B | 1 | $844K |
| 9 | 20149 | Ashburn | 83 | B | 1 | — |
| 10 | 20158 | Hamilton | 83 | B | 1 | $771K |
| 11 | 20159 | Hamilton | 83 | B | 1 | — |
| 12 | 20176 | Leesburg | 83 | B | 0 | $702K |
| 13 | 20177 | Leesburg | 83 | B | 0 | — |
| 14 | 20178 | Leesburg | 83 | B | 0 | — |
| 15 | 20180 | Lovettsville | 83 | B | 0 | $629K |
| 16 | 22093 | Ashburn | 83 | B | 1 | — |
| 17 | 20117 | Middleburg | 78 | B | 2 (2 health) | $948K |
| 18 | 20175 | Leesburg | 78 | B | 0 | $718K |
| 19 | 20118 | Middleburg | 77 | B | 2 (2 health) | — |
| 20 | 20129 | Paeonian Springs | 63 | C | 0 | $1206K |
| 21 | 20131 | Philomont | 63 | C | 0 | — |
| 22 | 20160 | Lincoln | 63 | C | 0 | — |
| 23 | 20166 | Sterling | 63 | C | 0 | $576K |
| 24 | 20169 | Haymarket | 55 | C | 0 | $677K |
| 25 | 20101 | Dulles | 53 | D | 0 | — |
| 26 | 20102 | Dulles | 53 | D | 0 | — |
| 27 | 20103 | Dulles | 53 | D | 0 | — |
| 28 | 20104 | Dulles | 53 | D | 0 | — |
| 29 | 20140 | Rectortown | 53 | D | 0 | — |
| 30 | 20184 | Upperville | 53 | D | 0 | — |
| 31 | 20189 | Dulles | 53 | D | 0 | — |
| 32 | 20197 | Waterford | 53 | D | 0 | $989K |
| 33 | 20198 | The Plains | 53 | D | 0 | $1131K |
Recommended Buyer Guides for Loudoun County
While many sites publish identical guide lists across every county they cover, the selection here changes by location — driven by the EPA, NSF, FEMA, and CDC datasets that describe the actual conditions documented for this jurisdiction in the federal record.
- Best Under-Sink Reverse Osmosis Systems — Multi-contaminant removal at the kitchen tap
Deep Dive Reports
Detailed analysis for Loudoun County, Virginia
Overview
Loudoun County in Virginia covers 33 ZIP codes with an average Home Safety Score of B (71/100).
10 of 33 ZIP codes have recorded EPA violations. 4 health-based violations have been documented.
← Back to Virginia 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.