Tap Water Quality Report
Tap water quality in HERNDON, Virginia
Tap water in HERNDON, Virginia receives a grade of D (63/100) from TapWaterSafety.org. It's served by FAIRFAX COUNTY WATER AUTHORITY. The most significant water quality concerns are: PFAS contamination; Haloacetic acids (HAA9) significantly above health guideline; Total trihalomethanes (TTHMs) significantly above health guideline; Haloacetic acids (HAA5) significantly above health guideline. Data sources: EPA SDWIS, EPA ECHO, EWG Tap Water Database.
What's in HERNDON's tap water
Top water quality concerns identified by the EPA and Environmental Working Group across the utility serving HERNDON.
PFAS contamination
Severe concernPerfluorooctanoic acid (PFOA), Perfluorooctane sulfonate (PFOS) detected. PFAS are persistent chemicals linked to cancer and immune effects with no known safe exposure threshold.
Haloacetic acids (HAA9) significantly above health guideline
Moderate concernHaloacetic acids (HAA9) detected at 26.6 ppb, 444x above the EWG health guideline of 0.06 ppb.
Total trihalomethanes (TTHMs) significantly above health guideline
Moderate concernTotal trihalomethanes (TTHMs) detected at 27.8 ppb, 186x above the EWG health guideline of 0.15 ppb.
Haloacetic acids (HAA5) significantly above health guideline
Moderate concernHaloacetic acids (HAA5) detected at 16.4 ppb, 164x above the EWG health guideline of 0.1 ppb.
EPA compliance record
Official U.S. EPA records for FAIRFAX COUNTY WATER AUTHORITY (system ID VA6059501) for the last 3 years. Checked 2026-10-07.
Source: U.S. EPA Enforcement and Compliance History Online (ECHO), from the Safe Drinking Water Information System. See EPA's full report.
Recommended filters for HERNDON
Filters matched to the specific contaminants in HERNDON's water supply.
Filter certified for PFOA/PFOS (NSF/ANSI 53 or 58)
$180-$750Reverse osmosis and some carbon block filters reduce PFAS. Look for certification to NSF/ANSI 53 or 58 for PFOA/PFOS.
Carbon filter certified for VOCs (NSF/ANSI 53)
$180-$599Activated carbon is effective for disinfection byproducts. Look for NSF/ANSI 53 VOC reduction.
Disclosure: TapWaterSafety earns a commission from purchases made through these links. This does not influence our scoring methodology or filter selection.
All contaminants detected in HERNDON's tap water
Every contaminant identified, compared side-by-side against US EPA legal limits, the EU Drinking Water Directive (2020/2184), WHO Guidelines, and California's Public Health Goal. Why we show multiple standards →
| Contaminant | Detected | EWG US health-based |
EPA US legal |
EU DWD Europe |
WHO global |
CA PHG strictest US |
Tested sample year |
Status |
|---|---|---|---|---|---|---|---|---|
| Haloacetic acids (HAA9) Disinfection byproduct |
26.6 ppb | 0.06 | — | — | — | — | — | 444× over |
| Total trihalomethanes (TTHMs) Disinfection byproduct |
27.8 ppb | 0.15 | 80.0 | 100 | — | — | — | 186× over |
| Haloacetic acids (HAA5) Disinfection byproduct |
16.4 ppb | 0.1 | 60.0 | 60 | — | — | — | 164× over |
| Bromodichloromethane Disinfection byproduct |
6.59 ppb | 0.06 | — | — | — | — | — | 110× over |
| Trichloroacetic acid Disinfection byproduct |
6.41 ppb | 0.1 | — | — | — | — | — | 64× over |
| Chloroform Disinfection byproduct |
17.7 ppb | 0.4 | — | — | — | — | — | 44× over |
| Dichloroacetic acid Disinfection byproduct |
8.72 ppb | 0.2 | — | — | — | — | — | 44× over |
| Dibromochloromethane Disinfection byproduct |
3.3 ppb | 0.1 | — | — | — | — | — | 33× over |
| Dibromoacetic acid Disinfection byproduct |
0.703 ppb | 0.03 | — | — | — | — | — | 23× over |
| Nitrate Inorganic |
1.12 ppm | 0.14 | 10.0 | 11.3 | 11.3 | 10 | — | 8.0× over |
| Nitrate and nitrite Inorganic |
1.12 ppm | 0.14 | 10.0 | 11.3 | 11.3 | 10 | — | 8.0× over |
| Chromium (hexavalent) Heavy metal |
0.103 ppb | 0.02 | — | — | — | — | — | 5.2× over |
| Perfluorooctanoic acid (PFOA) PFAS |
0.417 ppt | 0.09 | 4.0 | 100 | 100 | 0.007 | — | 4.6× over |
| 6:2 Fluorotelomer Sulfonic Acid (6:2 FTSA) Other |
3.17 ppt | 1.0 | — | — | — | — | — | 3.2× over |
| Perfluorooctane sulfonate (PFOS) PFAS |
0.392 ppt | 0.3 | 4.0 | 100 | 100 | 1 | — | 1.3× over |
| Chlorate Disinfection byproduct |
184.1 ppb | 210.0 | — | — | — | — | — | Below guideline |
| Bromoform Disinfection byproduct |
0.269 ppb | 0.5 | — | — | — | — | — | Below guideline |
| Radium, combined (-226 and -228) Radiological |
0.02 pCi/L | 0.05 | 5.0 | — | — | — | — | Below guideline |
| Barium Heavy metal |
31.1 ppb | 700.0 | 2000.0 | — | 1300 | 2000 | — | Below guideline |
| Aluminum Heavy metal |
10.2 ppb | 600.0 | — | 200 | — | 600 | — | Below guideline |
| Vanadium Other |
0.347 ppb | 21.0 | — | — | — | — | — | Below guideline |
| Monochloroacetic acid Disinfection byproduct |
0.324 ppb | 53.0 | — | — | — | — | — | Below guideline |
| Perfluoropentanoic Acid (PFPeA) PFAS |
2.88 ppt | 1000.0 | — | — | — | — | — | Below guideline |
| Molybdenum Other |
0.114 ppb | 40.0 | — | — | — | — | — | Below guideline |
| Perfluorohexanoic Acid (PFHxA) PFAS |
2.71 ppt | 1000.0 | — | — | — | — | — | Below guideline |
| Manganese Heavy metal |
0.0881 ppb | 100.0 | — | 50 | 80 | — | — | Below guideline |
| Perfluorobutanoic Acid (PFBA) PFAS |
0.8 ppt | 1000.0 | — | — | — | — | — | Below guideline |
| Perfluorobutane sulfonate (PFBS) PFAS |
0.725 ppt | 2000.0 | — | — | — | — | — | Below guideline |
| Perfluoroheptanoic acid (PFHPA) PFAS |
0.325 ppt | 1000.0 | — | — | — | — | — | Below guideline |
| Strontium Radiological |
0.127 ppb | 1500.0 | — | — | — | — | — | Below guideline |
| Fluoride Inorganic |
0.674 ppm | — | 4.0 | 1.5 | 1.5 | — | — | Below guideline |
| Nitrite Inorganic |
0.000957 ppm | — | 1.0 | — | — | — | — | Below guideline |
All values in the unit of the detected level. Red cells indicate the detected level exceeds that standard. Some contaminants have limits in some jurisdictions but not others (shown as —). The "Tested" column shows the year each contaminant sample was collected.
Sources: US EPA, EU Drinking Water Directive 2020/2184, WHO Guidelines, California OEHHA PHGs, EWG Tap Water Database.
Treatment plant contact info
For service issues, water quality concerns, or to request a Consumer Confidence Report from FAIRFAX COUNTY WATER AUTHORITY.