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EPA ID VA6059501 · checked 16 Oct 2026

Fairfax County tap water: what EPA testing found

Fairfax Water (Fairfax County Water Authority) (EPA record: FAIRFAX COUNTY WATER AUTHORITY) serves 1,121,613 people in VA from surface water.

What the data shows

PFAS and lithium (EPA UCMR 5)

720 results from 6 sampling points, 26 Mar 2024 to 13 Feb 2025. Averages count results below EPA’s reporting level as zero, as the PFAS rule does. Every number links to EPA’s UCMR 5 Data Finder (search PWSID VA6059501). Limits: EPA PFAS rule.

ContaminantDetected inHighest resultAverageEPA limit
PFOA3 of 247.4 ng/L0.77 ng/L4 ng/L
PFOS2 of 245.7 ng/L0.43 ng/L4 ng/L
PFHxS0 of 24not detected0 ng/L10 ng/L*
PFNA0 of 24not detected0 ng/L10 ng/L*
HFPO-DA0 of 24not detected0 ng/L10 ng/L*
PFBS5 of 248.1 ng/L1.13 ng/Lnone
PFBA3 of 2417.6 ng/L1.86 ng/Lnone
PFHxA10 of 2417.1 ng/L2.92 ng/Lnone
PFHpA3 of 245.6 ng/L0.6 ng/Lnone
PFPeA10 of 2421.5 ng/L3.4 ng/Lnone
6:2 FTS4 of 2410.1 ng/L1.58 ng/Lnone
Lithium0 of 24not detected0 µg/Lnone (screening level 10 µg/L)

* PFHxS, PFNA and HFPO-DA limits (and the PFAS hazard index) are in the rule, but EPA proposed on 20 May 2026 to rescind them; not final as of 16 Oct 2026. UCMR 5 results are screening data, not compliance results: compliance uses quarterly running averages from 2029. Source file: EPA UCMR 5 occurrence data (dated 15 Oct 2026).

Sampling points averaging above a limit

FacilityWaterSamplesPFOA avgPFOS avgAbove
Griffith WTPsurface44.63 ng/L2.6 ng/LPFOA

Health-based violations since 2016

None in EPA’s SDWIS data.

Source: EPA SDWIS via Envirofacts and the ECHO report for VA6059501, retrieved 16 Oct 2026.

Hardness

8.2 grains per gallon (highest plant or source figure of 4, 2025; varies by area), from the utility’s water report checked 17 Oct 2026. Size a softener for this water.

Plant, source or areaServesGrains per gallon
James J. Corbalis Jr. Water Treatment Plant (Potomac River)Fairfax Water plants' area; generally the north of the county7.47 (4.09–10.8)
Frederick P. Griffith Jr. Water Treatment Plant (Occoquan Reservoir)Fairfax Water plants' area; generally the south of the county5.61 (2.98–8.01)
Dalecarlia Water Treatment Plant (Washington Aqueduct, Potomac River)Washington Aqueduct area (report map p.6)8.23 (6.2–10.9)
McMillan Water Treatment Plant (Washington Aqueduct, Potomac River)Washington Aqueduct area (report map p.6)7.93 (5.61–10.5)

From the same report. Which plant or source serves an address depends on where it is; the utility’s report explains its areas.

46 of this system’s ZIP codes are placed in a plant’s service area using the utility’s service-area map (checked 17 Oct 2026); the ZIP checker shows your ZIP code’s figure.

Places and ZIP codes served

Alexandria, Fairfax, Falls Church, Reston, Springfield, Herndon, Vienna, Arlington, Centreville, Chantilly, Mc Lean, Annandale, Burke, Clifton, Dunn Loring, Fairfax Station, Fort Belvoir, Great Falls, Lorton, Newington, Oakton, Sterling.

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ZIP codes the system reported to EPA for UCMR 5; place names from GeoNames (CC BY 4.0). A ZIP code can be split between systems.