Fairfax County Water Quality: 3 Cities Ranked by the Records
Fairfax County, Virginia: 3 city reports built from EPA and utility records. A county has many suppliers; each city shows the system that serves it.
Highest result for each contaminant
One row per contaminant: the highest result any system in the county reported, against its limit. Open a row for the systems behind it.
Lead (90th percentile)Detected in 2 systems of 3 tested15 µg/L federal action level · US EPAHighest0.629 µg/L
- VIENNA, TOWN OF0.629 µg/LMonitoring period: 2023–2025
- HERNDON, TOWN OF0.392 µg/LMonitoring period: 2021–2023
- ALEXANDRIA, CITY OFNot detectedMonitoring period: 2023–2025
Perfluorobutanesulfonic acid (PFBS)Detected in 1 system of 3 tested2,000 ng/L EPA health advisory (screening, not a legal limit) · US EPAHighest3.5 ng/L
- ALEXANDRIA, CITY OF3.5 ng/LSample date: 2023-09-04 to 2024-06-09
- HERNDON, TOWN OFNot detected · below 3.0 ng/L lab reporting limitSample date: 2023-05-16 to 2024-02-05
- VIENNA, TOWN OFNot detected · below 3.0 ng/L lab reporting limitSample date: 2023-08-30 to 2024-05-21
Perfluorohexanoic acid (PFHxA)Detected in 3 systems400,000 ng/L Michigan EGLE state MCL (strictest US state) · Michigan EGLEHighest4.9 ng/L
- ALEXANDRIA, CITY OF4.9 ng/LSample date: 2023-09-04 to 2024-06-09
- VIENNA, TOWN OF3.8 ng/LSample date: 2023-08-30 to 2024-05-21
- HERNDON, TOWN OF3.1 ng/LSample date: 2023-05-16 to 2024-02-05
Perfluorobutanoic acid (PFBA)Detected in 1 system of 3 testedNo federal or state limit; shown for transparencyHighest6.8 ng/L
- HERNDON, TOWN OF6.8 ng/LSample date: 2023-05-16 to 2024-02-05
- ALEXANDRIA, CITY OFNot detected · below 5.0 ng/L lab reporting limitSample date: 2023-09-04 to 2024-06-09
- VIENNA, TOWN OFNot detected · below 5.0 ng/L lab reporting limitSample date: 2023-08-30 to 2024-05-21
Perfluoropentanoic acid (PFPeA)Detected in 3 systemsNo federal or state limit; shown for transparencyHighest6.4 ng/L
- ALEXANDRIA, CITY OF6.4 ng/LSample date: 2023-09-04 to 2024-06-09
- VIENNA, TOWN OF5.4 ng/LSample date: 2023-08-30 to 2024-05-21
- HERNDON, TOWN OF3.9 ng/LSample date: 2023-05-16 to 2024-02-05
26 substances tested, none detected in any systemShow
Tested in these 3 systems: ALEXANDRIA, CITY OF, HERNDON, TOWN OF, VIENNA, TOWN OF
- 11-Chloroeicosafluoro-3-oxaundecane-1-sulfonic acid (11Cl-PF3OUdS)
- 1H, 1H, 2H, 2H-perfluorodecane sulfonic acid (8:2 FTS)
- 1H, 1H, 2H, 2H-perfluorohexane sulfonic acid (4:2 FTS)
- 1H, 1H, 2H, 2H-perfluorooctane sulfonic acid (6:2 FTS)
- 4,8-Dioxa-3H-perfluorononanoic acid (ADONA)
- 9-Chlorohexadecafluoro-3-oxanone-1-sulfonic acid (9Cl-PF3ONS)
- Hexafluoropropylene oxide dimer acid (HFPO-DA) (GenX chemicals)
- Lithium
- N-ethyl perfluorooctanesulfonamidoacetic acid (NEtFOSAA)
- N-methyl perfluorooctanesulfonamidoacetic acid (NMeFOSAA)
- Nonafluoro-3,6-dioxaheptanoic acid (NFDHA)
- Perfluoro (2-ethoxyethane) sulfonic acid (PFEESA)
- Perfluoro-3-methoxypropanoic acid (PFMPA)
- Perfluoro-4-methoxybutanoic acid (PFMBA)
- Perfluorodecanoic acid (PFDA)
- Perfluorododecanoic acid (PFDoA)
- Perfluoroheptanesulfonic acid (PFHpS)
- Perfluoroheptanoic acid (PFHpA)
- Perfluorohexanesulfonic acid (PFHxS)
- Perfluorononanoic acid (PFNA)
- Perfluorooctanesulfonic acid (PFOS)
- Perfluorooctanoic acid (PFOA)
- Perfluoropentanesulfonic acid (PFPeS)
- Perfluorotetradecanoic acid (PFTA)
- Perfluorotridecanoic acid (PFTrDA)
- Perfluoroundecanoic acid (PFUnA)
Cities ranked by the records
Ranked by the Purity Score of each city's main water system, highest first. Scores belong to water systems; there is no county score. The score is computed only from contaminants measured in the published EPA record, so this ranks the record, not which city's water is safest. How the score works.
0of 3 cities above the 15 µg/L action level
Based on each system's 90th-percentile result. Lead from household plumbing isn't in this record.
Lead in VirginiaLargest water systems
- AlexandriaALEXANDRIA, CITY OF · VA6510010159,200 served
- ViennaVIENNA, TOWN OF · VA605980027,134 served
- HerndonHERNDON, TOWN OF · VA605955024,601 served
Frequently asked
How does Fairfax County tap water compare across cities?
PurityMap ranks 3 cities in Fairfax County by the Purity Score of each city's main water system, computed only from contaminants measured in the published EPA record. Scores belong to water systems, not to cities. The highest published score is Alexandria's main water system: ALEXANDRIA, CITY OF · PWSID VA6510010 · Purity Score 100 (Excellent) · Confidence: moderate · Assessed at the water-system level. The ranking compares the records, not which city's water is safest, and your own tap can differ with household plumbing.
How many Fairfax County cities had a PFAS sample above a 2024 EPA limit?
None of the 3 Fairfax County city reports had a PFAS sample above a 2024 EPA limit in EPA's UCMR 5 testing. PFAS were detected below the limit in 3.
Is there lead in Fairfax County tap water?
Utilities report lead as a 90th-percentile result from home taps. 2 of 3 Fairfax County cities reported a value above zero, and none was above the 15 µg/L federal action level. Lead usually comes from a building's own pipes and fixtures, so only a test at your tap tells you what you drink.
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