Nitrate is worth checking in Washington County wells.
1 worth checking, 4 rare out of 5 health checks.
From 16 wells tested in Washington County since 2000; your own well needs its own test. How to read this
Not charted, because fewer than 10 wells were tested: uranium (6), radon (2).
Rare: under 5%Worth checking: 5 to 15%Widespread: 15%+
Lab results: Water Quality Portal (USGS and EPA)
Who drinks from a well here
1 in 3 people 47,710 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 Washington County compares with Maryland and the counties around it.
Each result puts Washington County next to the 8 counties that border it, on the chart's 0 to 50% scale.
This one is worth checking in Washington County.
Nitrate2 of 16 wells over
Too few tested to show: Allegany, Berkeley, WV, Fulton, PA, Loudoun, VA.
These 4 are rare in Washington County.
Manganese0 of 15 wells over
* Likely overstated, so we don't rank it.
Too few tested to show: Allegany, Berkeley, WV, Fulton, PA, Loudoun, VA.
Arsenic0 of 15 wells over
Too few tested to show: Allegany, Berkeley, WV, Fulton, PA, Loudoun, VA.
Lead0 of 15 wells over
Too few tested to show: Allegany, Berkeley, WV, Fulton, PA, Loudoun, VA.
Fluoride0 of 15 wells over
Too few tested to show: Allegany, Berkeley, WV, Fulton, PA, Loudoun, VA.
Too few Washington County wells were tested for these 2.
Uranium6 wells tested
Radon in water2 wells tested
Coliform bacteria turned up in 1 of 1 tested Washington County wells, so test for it every year.
Coliform bacteria1 of 1 wells had it
E. coli0 of 1 wells had it
E. coli means human or animal waste is getting in, so if a test of your Washington County well finds it, boil drinking water until the well is fixed.
Iron reached staining levels in 1 of 15 tested wells, and it isn't a health risk.
Iron stains1 of 15 wells had it
Too few tested to show: Allegany, Berkeley, WV, Fulton, PA, Loudoun, VA.
Most of the 16 wells tested in Washington County were last tested before 2010.
An old result shows the water as it was then, so treat these 16 wells as a starting point and test your own.
Most Washington 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 3 things to check in Washington County.
- Bacteria
- Nitrate
- Arsenic
What Maryland offers well owners
- Free testingWe didn't find a free program for all of Maryland. Maryland's private well page
- Certified labsMaryland's list of certified labs
- Well recordsWe didn't find an online search.
- New wellsSince October 1, 2024, Md. Code, Real Property 10-713 requires a contract for sale of property with a private well to make well water quality testing a condition of sale, with both parties certifying they reviewed the results.
Half the household wells here are shallower than 200 feet.
That comes from 14,867 household wells in Maryland's drilling records. Most wells of every kind here are 125 to 305 feet deep. Wells as deep as Washington 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 household wells here go deeper than in 12 of the 23 other Maryland 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 Washington County.
Washington 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 3 town water systems in Washington County test for PFAS. 1 of them had at least one test above 4 ng/L, the new EPA limit for PFOA and PFOS. The highest single result was 6.7 ng/L of PFOA. No well in Washington 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 Washington County
Is well water in Washington County safe to drink?
2 of 16 wells tested in Washington County had nitrate over the limit, about 1 in 8. Across Maryland it's about 1 in 10. That's a bigger share than in 13 of the 17 other Maryland counties with 10 or more tested wells, leaving out 1 county whose results are likely overstated. So test your own well for nitrate before you count on it.
Where can I get my well tested in Washington County?
Use a lab Maryland has certified for drinking water. Maryland's list is linked above, in the box about testing. Ask for bacteria, nitrate and arsenic, the tests that matter most in Washington County.
How deep are wells in Washington County?
Half the household wells here are shallower than 200 feet. Typical household wells here go deeper than in 12 of the 23 other Maryland counties with enough drilling records.
How does Washington County compare with the counties around it?
For nitrate, the share of tested wells over the limit: Washington County, at 12%, had a higher share than all 4 neighboring counties with data. Groundwater doesn't stop at county lines, so Jefferson, WV's 8% is worth knowing about if you live near it.
How often should I test my well in Washington County?
In Washington County, 1 of 1 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.
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Where the Washington County numbers come from
- People on wells: 47,710 in Washington County, from EPA estimates built on the 2020 Census (Murray et al.).
- Lab tests: 194 well water samples from 16 wells in the Water Quality Portal, run by the USGS and EPA, 2000 to 2022.
- Well depths: 14,867 Maryland drilling records for Washington County, gathered in the US Groundwater Well Database (Lin and others, 2024).
- Neighboring counties: the 8 counties that share a border with Washington County, from the Census Bureau's county adjacency file.
- PFAS: EPA tests of 3 town water systems in Washington County under the Fifth Unregulated Contaminant Monitoring Rule, 2023 to 2025.
- Radon: Washington County is zone 1 on the EPA Map of Radon Zones.
- State programs and links: Maryland Department of the Environment, checked November 1, 2026.