Is Herndon, VA tap water safe?

Data: U.S. EPA · How we read the data · How we check it

Fairfax County Water Authority, the largest system here, had PFAS above the 2024 federal limits (PFOA) in EPA's 2023–2025 testing.

Is it an emergency? No: PFAS limits are about years of exposure, not a glass of water, and nothing in EPA's data calls for you to stop drinking the water today. If your utility issues a boil-water or do-not-drink notice, follow it.

3 public water systems serve parts of Herndon. The largest, Fairfax County Water Authority, serves 1.1 million people, and one system here had PFAS above a federal limit. Your water bill names your system.

Largest system

Fairfax County Water Authority

1.1 million people · Surface water · EPA ID VA6059501

Buys treated water from Washington Aqueduct Division..

PFAS	Highest average	Limit	Status
PFOA Above limit	4.63 ppt	4 ppt	Above limit
PFOS One sample above limit	2.6 ppt	4 ppt	One sample above limit
PFHxS Not detected	–	10 ppt	Not detected
PFNA Not detected	–	10 ppt	Not detected
HFPO-DA (GenX) Not detected	–	10 ppt	Not detected

ppt = parts per trillion. "Highest average" is the highest average at any of the system's entry points, the way EPA compares results with the limits.

For context: the PFOA average is higher than at 96% of the Virginia systems EPA tested.

Lead: 1.2 ppb at the 90th percentile (Dec 2023, and 9 in 10 homes sampled were at or below it) Below action level
Health-based violations since 2016: 0

Full Fairfax County Water Authority results

Across Virginia, 12 of 164 water systems EPA tested had PFAS above a 2024 federal limit, and 3 systems were above the lead action level in results from the last five years. Virginia results.

Herndon homes and lead pipes

43%

of homes built before 1980 (Virginia 44%, US 50%)

built before 1950 (Virginia 11%)

38%

of households rent (Virginia 33%)

Lead service lines and lead solder were allowed until 1986, so homes from before then are the ones to check. Renting? Ask your landlord what the service line is made of, because it's their pipe to replace. How to check your own line.

Housing: Census American Community Survey 2020–2024 5-year estimates for Herndon town (tables B25034, B25003). Estimates for small places have a margin of error.

Other water systems serving Herndon

Loudoun Water – Central System
334,808 people · Surface water · Virginia · reported ZIPs here
No PFAS above limits
Town of Herndon
24,601 people · Purchased surface water · Virginia · lists this city
No PFAS above limits

How nearby cities compare

City	Main water system	PFAS	Lead (90th pct.)
Leesburg 13 mi Town of Leesburg	Town of Leesburg	None above limits	0 ppb
Manassas 16 mi Prince William Water – West	Prince William Water – West	None above limits	0 ppb
Alexandria 19 mi Fairfax County Water Authority	Fairfax County Water Authority	Above limit	1.2 ppb
Winchester 45 mi City of Winchester	City of Winchester	None above limits	2.7 ppb
Fredericksburg 47 mi City of Fredericksburg	City of Fredericksburg	None above limits	0 ppb
Charlottesville 87 mi City of Charlottesville	City of Charlottesville	None above limits	0 ppb

Herndon ZIP codes (1)

20170

Questions

Is Herndon tap water safe to drink?

Fairfax County Water Authority has had no health-based violations since 2016, and EPA testing found PFAS above the 2024 federal limits, which it must meet by 2029. Utility data can't show lead from your own pipes: if your home was built before 1986, test your tap. Your utility's annual Consumer Confidence Report is the official summary.

Who supplies water in Herndon, VA?

3 public water systems serve parts of Herndon. The largest is Fairfax County Water Authority (1.1 million people). Your water bill names your system. The EPA ID is also on your utility's Consumer Confidence Report.

Does Herndon tap water have PFAS?

Yes. EPA's 2023–2025 testing found entry-point averages above the 2024 federal limits for PFOA at Fairfax County Water Authority. Systems have until 2029 to meet them.

Do Herndon homes have lead pipes?

Census estimates put 43% of Herndon homes as built before 1980 (Virginia: 44%). Lead service lines and lead solder were allowed until 1986, so older homes are more likely to have them. Fairfax County Water Authority's service line inventory says what your line is made of. The only way to know for your home is to check the line where it enters the house and test your tap.

Source: U.S. EPA drinking water records and PFAS testing (UCMR 5). How we read the data.