EPA system VA6107350 · Virginia

Loudoun Water - Central System: 1 PFAS found; PFPeA up to 3.4 ppt, no EPA limit set

System ID VA6107350; community water system; Virginia; source: surface water; serves 334,808 people via 83,426 connections; status: active

In focus334,808people served, EPA registry

Public records. Clearer context.

Loudoun Water - Central System is a local-government-owned community water system in Virginia serving about 334,808 people, matched to 13 ZIP codes.

PFAS treatment declared to EPA: None declared (8 of 8 sampling events) · PFAS found before UCMR 5: Yes, at 8 of 8 sampling events

PFAS and lithium: what EPA's national survey found

EPA tested this water for 30 substances and found 1.

Between June 2023 and March 2024, EPA's UCMR 5 program tested 240 samples from 2 sampling locations for 30 contaminants (29 PFAS plus lithium). 1 were detected above the reporting level in at least one sample.

Sampling-point average: mean of a location's two (ground water) or four (surface water) UCMR 5 results with non-detects counted as zero, EPA's method for comparing UCMR 5 data to the PFAS MCLs. EPA rounds to the reference value's significant digits before deciding whether an average is "greater than" an MCL (PFOA/PFOS averages count as above 4.0 ng/L only from 4.05 ng/L; lithium results count as above the 10 ppb reference only from 15 ppb). This site does not apply that rounding: "at or above" here means the measured value is numerically at or above the reference.

Utility-reported context (UCMR 5 questionnaire, aggregated across sampling events): PFAS previously found at this system: yes at 8 of 8 sampling events; potential PFAS sources nearby: no at 8 of 8 sampling events; PFAS treatment in place: no PFAS treatment at 8 of 8 sampling events.

Lead at customer taps

In the latest completed monitoring period, ending Dec 31, 2023, 9 in 10 sampled homes had lead at or below 0 ppb, below the 15 ppb action level that triggers utility action. The action level has been reached in 5 of the 22 periods on record.

In the most recent completed lead monitoring period, ending Dec 31, 2023, the 90th-percentile lead result at customer taps was 0 ppb, below the action level of 15 ppb; 5 of the 22 monitoring periods on record reached the action level. The 90th percentile is the value that 9 in 10 sampled homes were at or below. Values are in parts per billion (ppb).

Drinking water violations since Sep 3, 2016

EPA lists 1 violation since Sep 3, 2016. None is health-based. All concern missed monitoring, reporting or public notices, not the water itself.

EPA's SDWIS database lists 1 violation recorded since Sep 3, 2016: 1 for monitoring or reporting, none health-based.

Sanitary surveys and site visits

Most recent state inspection: Feb 26, 2024 (sanitary survey); 2 visits since Sep 3, 2021.

What you can do about these results

ZIP codes served

Sources

Data vintage: EPA UCMR 5 occurrence data, samples collected 2023-01-03 – 2026-06-17, final release, August 2026 (file dated Aug 28, 2026); EPA SDWIS via ECHO, 2026Q2 extract (file dated Jul 9, 2026); EPA service-area boundaries v3.0; Census 2020 ZCTAs. Page generated 2026-09-03.

• EPA ECHO detailed facility report
• EPA UCMR 5 Data Finder
• EPA service-area boundary: modeled, 134.4 sq mi