Manganese is widespread in Fairfax County wells.
1 widespread, 5 rare out of 6 health checks.
From 10 wells tested in Fairfax County since 2003; your own well needs its own test. How to read this
Rare: under 5%Worth checking: 5 to 15%Widespread: 15%+
Lab results: Water Quality Portal (USGS and EPA)
Who drinks from a well here
About 1 in 34 people 33,731 people
Nobody else tests these wells. Only you do.
People on wells: EPA researchers' 2020 estimate
How deep wells go here
Deep wells: fewer surface germs, more minerals from the rock.
Well depths: US Groundwater Well Database
Radon risk (a gas from rock)
Likely here. Test your home's air first.
Radon zones: EPA map
Here's how Fairfax County compares with Virginia and the counties around it.
Each result puts Fairfax County next to the 9 counties that border it, on the chart's 0 to 50% scale.
This one is widespread in Fairfax County wells.
Manganese2 of 10 wells over
* Likely overstated, so we don't rank it.
Too few tested to show: Alexandria city, Arlington, Fairfax city, Falls Church city, Loudoun, Prince George's, MD.
These 5 are rare in Fairfax County.
Nitrate0 of 10 wells over
Too few tested to show: Alexandria city, Arlington, Fairfax city, Falls Church city, Loudoun, Prince George's, MD.
Fluoride0 of 10 wells over
Too few tested to show: Alexandria city, Arlington, Fairfax city, Falls Church city, Loudoun, Prince George's, MD.
Arsenic0 of 10 wells over
Too few tested to show: Alexandria city, Arlington, Fairfax city, Falls Church city, Loudoun, Prince George's, MD.
Uranium0 of 10 wells over
Too few tested to show: Alexandria city, Arlington, Fairfax city, Falls Church city, Loudoun, Prince George's, MD.
Lead0 of 10 wells over
Too few tested to show: Alexandria city, Arlington, Fairfax city, Falls Church city, Loudoun, Prince George's, MD.
Coliform bacteria turned up in 2 of 4 tested Fairfax County wells, so test for it every year.
Coliform bacteria2 of 4 wells had it
E. coli0 of 4 wells had it
E. coli means human or animal waste is getting in, so if a test of your Fairfax County well finds it, boil drinking water until the well is fixed.
Iron reached staining levels in 3 of 10 tested wells, and it isn't a health risk.
Iron stains3 of 10 wells had it
Too few tested to show: Alexandria city, Arlington, Fairfax city, Falls Church city, Loudoun, Prince George's, MD.
Fairfax County has 10 tested wells, and the busiest decade for testing was the 2010s.
None of the 10 wells has a test from 2020 or later, so a fresh test of your own well tells you more than any of these.
Most Fairfax County wells in these records were tested for research or because someone suspected a problem, which can push the shares above what a typical home well would show (how we read the numbers).
One mail-in lab test covers the 4 things to check in Fairfax County.
- Bacteria
- Nitrate
- Manganese
- Arsenic
What Virginia offers well owners
- Free testingVirginia Cooperative Extension's Virginia Household Water Quality Program runs drinking water clinics in about 70 counties each year at $70 per kit, with financial help available through SERCAP. See the program
- Certified labsVirginia's list of certified labs
- Well recordsWe didn't find an online search.
- New wellsVirginia's Private Well Regulations (12VAC5-630) require newly constructed wells to be tested for coliform bacteria as a condition for use; testing at home purchase is not required by VDH.
Half the wells on record here are shallower than 205 feet.
That comes from 2,042 wells in Virginia's drilling records. Most wells of every kind here are 150 to 312 feet deep. Wells as deep as Fairfax County's are usually better protected from fertilizer and bacteria at the surface, but they can pick up more of what's in the rock, like arsenic and uranium. Typical wells on record here are shallower than in 66 of the 102 other Virginia counties with enough drilling records.
How to find your own well's depth
Well depths: US Groundwater Well Database
Here's what we know about radon and PFAS in Fairfax County.
Fairfax County is in the EPA's highest radon zone. Radon from well water adds to the radon in your indoor air, so test your air first, and your water too if the air is high. Radon guide
Between 2023 and 2025 the EPA had 6 town water systems in Fairfax County test for PFAS. 3 of them had at least one test above 4 ng/L, the new EPA limit for PFOA and PFOS. The highest single result was 7.7 ng/L of PFOA. No well in Fairfax County has public PFAS results, so the town systems are the best clue to what's in the groundwater nearby. PFAS guide
Radon zones: EPA Map of Radon Zones. PFAS: EPA tests of town water systems, 2023 to 2025
Questions people ask about well water in Fairfax County
Is well water in Fairfax County safe to drink?
2 of 10 wells tested in Fairfax County had manganese over the limit, about 2 in 10. Across Virginia it's about 1 in 10. That's a bigger share than in 10 of the 11 other Virginia counties with 10 or more tested wells, leaving out 1 county whose results are likely overstated. So test your own well for manganese before you count on it.
Can I get my well tested for free in Fairfax County?
Virginia Cooperative Extension's Virginia Household Water Quality Program runs drinking water clinics in about 70 counties each year at $70 per kit, with financial help available through SERCAP. If not, use a lab Virginia has certified for drinking water. Ask for bacteria, nitrate, manganese and arsenic, the tests that matter most in Fairfax County.
How deep are wells in Fairfax County?
Half the wells on record here are shallower than 205 feet. Typical wells on record here are shallower than in 66 of the 102 other Virginia counties with enough drilling records.
How does Fairfax County compare with the counties around it?
For manganese, the share of tested wells over the limit: 1 of the 3 neighboring counties with data had a higher share than Fairfax County, at 20%. Prince William had the most, at 54%. Groundwater doesn't stop at county lines, so Prince William's 54% is worth knowing about if you live near it.
How often should I test my well in Fairfax County?
In Fairfax County, 2 of 4 tested wells had coliform bacteria, so the CDC's advice matters here: test for bacteria and nitrate every year, and right away after a flood, a repair, or any change in taste or smell.
If you buy something through our links, we may earn a commission. We'd recommend the same thing either way, and we'll tell you when a free option exists. How we make money
Where the Fairfax County numbers come from
- People on wells: 33,731 in Fairfax County, from EPA estimates built on the 2020 Census (Murray et al.).
- Lab tests: 178 well water samples from 10 wells in the Water Quality Portal, run by the USGS and EPA, 2003 to 2015.
- Well depths: 2,042 Virginia drilling records for Fairfax County, gathered in the US Groundwater Well Database (Lin and others, 2024).
- Neighboring counties: the 9 counties that share a border with Fairfax County, from the Census Bureau's county adjacency file.
- PFAS: EPA tests of 6 town water systems in Fairfax County under the Fifth Unregulated Contaminant Monitoring Rule, 2023 to 2025.
- Radon: Fairfax County is zone 1 on the EPA Map of Radon Zones.
- State programs and links: Department of Health (VDH), Office of Environmental Health Services, checked November 1, 2026.