States › Virginia › Loudoun County

Loudoun County, VA Water Quality

Water quality data for 9 public water systems serving Loudoun County, Virginia — based on EPA SDWIS enforcement records, lead testing results, and health-based violation history.

📅 2026 Report 🔄 Data updated 2026 Q2 📍 9 water systems · 29 cities
✅
Excellent — All Systems Performing Well

Water quality across the county is outstanding with minimal violations and very low lead levels.

A

Loudoun County Earns a A

Loudoun County: 29 communities across 9 water systems. 100.0% have no open violations.

  • Median lead where detected: 2.87 ppb
  • 4 communities with a lead detection, 25 reporting none detected
  • 2 communities with PFAS above the federal limit
  • 0 with significant inspection deficiencies
  • 100.0% of communities have no open violations
2.87 ppb
Median Lead Level
County-wide, 90th percentile
9
Water Systems
Active CWS & NTNCWS
100%
Violation-Free
No active violations on record
How we grade counties: MyWaterIQ uses EPA SDWIS enforcement data — actual MCL violations and lead test results — not the aspirational MCLG targets used by some sites. A grade reflects real compliance history, not theoretical risk. Learn more →

Cities by Water Quality

⭐ Best Performing
  • Leesburg
    Not detected
    No federal limits exceeded on record
    A
  • Ashburn
    Not detected
    No federal limits exceeded on record
    A
  • South Riding
    Not detected
    No federal limits exceeded on record
    A
  • Sterling
    Not detected
    No federal limits exceeded on record
    A
  • Brambleton
    Not detected
    No federal limits exceeded on record
    A
⚠ Needs Attention
  • Purcellville
    Not detected
    PFAS above the limit at 2 of 7 sampling points
    C
  • Round Hill
    3.44 ppb
    PFAS above the limit at 2 of 4 sampling points
    C
  • Aldie
    Not detected
    Copper above the 1,300 ppb action level
    B
  • Hillsboro
    0.97 ppb
    Copper above the 1,300 ppb action level
    B
  • Middleburg
    5.33 ppb
    Lead at 5.33 ppb, above a third of the action level
    B
County Lead Level — Median 2.87 ppb
Based on most recent 90th percentile lead tests across all reporting systems
0 ppb5 ppb10 ppb15 ppb
County median: 2.87 ppb — 19.1% of the federal action level
Systems by Lead Level
Under 5 ppb
3
5 – 10 ppb
1
No Data
25

All Cities in Loudoun County

Leesburg Not detected A
Ashburn Not detected A
South Riding Not detected A
Sterling Not detected A
Brambleton Not detected A
Stone Ridge Not detected A
Broadlands Not detected A
Cascades Not detected A
Sugarland Run Not detected A
Loudoun Valley Estates Not detected A
Lowes Island Not detected A
Countryside Not detected A
Belmont Not detected A
Lansdowne Not detected A
Purcellville Not detected C
Dulles Town Center Not detected A
Moorefield Not detected A
University Center Not detected A
Lovettsville 2.30 ppb B
Oak Grove Not detected A
Arcola Not detected A
Goose Creek Village Not detected A
One Loudoun Not detected A
Round Hill 3.44 ppb C
Middleburg 5.33 ppb B
Hamilton Not detected A
Kincora Not detected A
Aldie Not detected B
Hillsboro 0.97 ppb B
Showing 29 cities
No active violations Active violations

About Loudoun County Drinking Water

Loudoun County is served by 9 water systems covering 29 communities. No community here has an open violation on record.

Of the communities reporting lead results, 4 recorded a detection, with a median of 2.87 ppb — 19% of the federal action level. 25 reported none detected, which means below the laboratory limit rather than an absence of lead.

2 of 29 communities have PFAS above the limits EPA set in 2024, measured as a running annual average at each sampling point. State inspectors recorded no significant deficiencies.

Frequently Asked Questions

Is Loudoun County tap water safe to drink?▼
No community in Loudoun County has an open violation on record. 2 of 29 have PFAS above the federal limit, which is the main open concern.
What is the lead level in Loudoun County?▼
Among communities with a detection the median is 2.87 ppb, 19% of the 15 ppb action level. 25 reported none detected and 0 reported no result.
How many water systems serve Loudoun County?▼
9 community water systems serve 29 communities here.
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