Well water in Washington County, Ohio

In Washington County, none of 33 tested well samples exceeded the EPA limit for fluoride, based on public data from Ohio EPA Washington County residential well PFAS sampling and USGS Water Quality Portal.

The strongest signal is PFOA: 67% of 444 local samples were above the limit, too few samples to carry the headline but first on the test list below.

910 test results across 17 contaminants from at least 341 wells, 1978 to 2025; PFOA has the most at 444. Data refreshed September 22, 2026.

Compiled by Nick at Well Water Nerd from public records. How these pages are built

Ohio EPA sampled residential wells around the Chemours Washington Works site in Washington County, and wells with a detection are resampled quarterly. PFAS shares describe wells near a known source, not every well in the county. In that targeted sampling, 67% of 444 PFOA results in Washington County were above the EPA limit of 4 ng/L. In that targeted sampling, 1% of 74 PFOS results in Washington County were above the EPA limit of 4 ng/L.

An estimated 598 people in Washington County get their drinking water from a private well, per USGS 2015 county water use. That is about <1% of residents.

Separately, the USGS national arsenic model estimates that 2% of the 598 people on private wells in Washington County draw water above 10 ug/L (the model's range is 1% to 2%), from geology and well depth rather than local tests.

What individual samples found

Each row summarizes every public sample for that contaminant inside Washington County. Above limit means above the EPA maximum contaminant level; where EPA has no enforceable limit, the row shows a health guideline or nuisance level instead.

Contaminant	Above limit	Samples	Detected	Median	Highest	Limit
PFOA 2002 to 2025	67%	444	72%	44.5	22,100	4 ng/L EPA limit
PFOS 2019 to 2025	1%	74	11%	0	7.4	4 ng/L EPA limit
PFNA 2022 to 2025	0%	73	1%	0	2	10 ng/L EPA limit
PFHxS 2022 to 2025	0%	73	8%	0	7	10 ng/L EPA limit
Fluoride 1978 to 2019	0%	33	61%	0.2	1.2	4 mg/L EPA limit
Copper 1997 to 2019	0%	20	70%	0.002	0.016	1.3 mg/L EPA limit
Lead 1997 to 2019	0%	20	15%	0	10	15 ug/L EPA limit
Arsenic 2012 to 2019	0%	19	5%	0	0.16	10 ug/L EPA limit
Nitrate 1978 to 2019	0%	17	65%	1.47	7.99	10 mg/L EPA limit
Iron 1978 to 2019	no limit	33	42%	0	28,000	300 ug/L nuisance level
Manganese 1978 to 2019	no limit	33	45%	0	4,400	300 ug/L health guideline
Sodium 1978 to 2019	no limit	33	100%	25.8	250	20 mg/L health guideline
Chloride 1978 to 2019	no limit	33	100%	48	68	250 mg/L nuisance level

Sampled fewer than 10 times, too few to summarize: Radium (226 + 228) (2), E. coli (1), Uranium (1), Radon (1).

Over time

Share of samples above the limit by period. A cell needs ten samples to show; a comparison needs twenty in each period. Later periods sample fewer wells, and often the ones already known to have a problem.

Contaminant	before 2000	2000s	2010s	2020s
PFOA	n/a	60%135 samples	74%148 samples	65%161 samples
Fluoride	0%13 samples	n/a	0%20 samples	n/a

PFOA above the limit in Washington County fell from 74% of 148 samples in the 2010s to 65% of 161 in the 2020s.

Closer than the county

See the sampled wells near your address

The same records, drawn around one point: which wells within a few miles were sampled and what they found, how deep the wells next to you were drilled, and any leaking tank or cleanup site within a mile.

Check my address

What this means

The contaminants most often above their limit here are pfoa (67% of 444 samples) and pfos (1% of 74 samples). A well next door can differ sharply from yours because bedrock fractures, well depth and plumbing all matter, so these rates describe the area, not your tap.

Chloride is widespread in local groundwater. It is mainly a staining and taste problem, but high manganese also carries a health advisory for infants.

What to test for in Washington County

1
PFOA
67% of 444 local samples were above the limit.
2
PFOS
1% of 74 local samples were above the limit.
3
Coliform bacteria
Recommended for every private well, every year.
4
Radon
Median local reading is 410 pCi/L.
5
Nitrate
Recommended for every private well, especially near farms or septic systems.
6
Chloride
Detected in 100% of local samples.
7
Copper
Detected in 70% of local samples.
8
Volatile organic compounds (VOCs)
328 leaking underground storage tank sites on record locally.
9
Metals panel
11 hazardous waste sites on record locally.

Test your Washington County well for PFOA, PFOS and coliform bacteria

Certified lab analysis of your own tap water, bottles and prepaid return shipping included. The Essential well panel covers arsenic, uranium, nitrate, lead, copper, manganese, iron, sodium and bacteria; radon and PFAS are add-ons.

Order the Tap Score well water test kit, from $209 Already tested? Upload the report

Just want bacteria checked first? Tap Score coliform and E. coli test, $99. Coliform and E. coli are the tests every well needs every year.

Want a quick look before paying for a lab? Home well water test strips on Amazon check hardness, iron, pH and nitrate in minutes. They are a screen, not a result: arsenic, bacteria, uranium and PFAS need a certified lab.

Affiliate links: the merchant pays us a commission and the price is the same for you. It does not change what the data above says. As an Amazon Associate we earn from qualifying purchases.

Where to get a well tested in Ohio: certified labs, state programs and prices.

Already have results back? Get your lab report read against the Washington County numbers, $29. Every line explained, ranked by what matters, with the fix for each.

Wells in Washington County

1,100 domestic wells in Washington County are on record with the state since 1970. 91% are drilled into bedrock, and the typical well is 87 feet deep (one in ten goes past 160 feet).

In a typical Washington County well, bedrock starts about 20 feet down, the median yield is 3 gallons per minute, 49% of wells yield under 3 gallons per minute and usually need a storage tank.

Bedrock wells are where arsenic, uranium and radon come from: the water sits in fractures in granite and metamorphic rock and picks up whatever the rock carries. That is why testing for those three matters more here than in a dug or gravel well.

188

1970s

1980s

1990s

2000s

2010s

2020s

Find your own well's report

The state keeps the driller's report for most wells drilled since 1984. It tells you how deep your well is, where bedrock starts, and how much water it makes, which decides what treatment can work.

Open ODNR water well log search and choose Water Well.
The log lists depth, depth to bedrock, casing, static water level, the pump test and the driller.

Ohio has required well logs since 1948, so most drilled wells have one.

The rock under Washington County

Pennsylvanian aquifers

Sandstone. Sandstone wells draw from pore space in the rock and tend to be dependable. Iron, manganese and hardness are common, and some sandstones carry arsenic or radium, so a first test should include both.

Classification from the USGS Principal Aquifers of the United States (national map, 2003 edition, GIS release 2015), read at the county centroid. A single well can sit in a different unit, especially near a boundary.

Official help in Ohio

Two places to start that are not selling anything: the state program that answers private well questions, and its list of labs certified to run drinking water tests. A certified lab is the difference between a result you can act on and a number.

Private Water Systems Program, Ohio Department of Health
Laboratory Certification, Ohio EPA

Contamination sources on record in Washington County

Ohio EPA records 328 leaking underground storage tank sites and 11 hazardous waste sites in Washington County, among 365 regulated sites in total. Groundwater does not follow property lines, so a well within a few hundred feet of one of these is worth testing for what that site could release.

328: leaking underground storage tank sitesGasoline and heating oil that leaked from tanks move through groundwater as benzene, MTBE and other volatile organic compounds.
11: hazardous waste sitesSolvents, degreasers and metals from industrial sites can travel far in fractured bedrock.
11: lined landfills and transfer facilities
15: other remediation projects

Treatment that fits the local profile

PFOA

Granular activated carbon whole-house; Point-of-use reverse osmosis; Anion exchange

PFOS

Granular activated carbon whole-house; Point-of-use reverse osmosis; Anion exchange

Iron

Oxidizing filter whole-house; Water softener (low levels); Aeration plus filtration

Manganese

Oxidizing filter (greensand, birm) whole-house; Water softener (low levels); Point-of-use reverse osmosis

Systems we would look at first

Some links below are affiliate links. If you buy through one, the merchant pays us a commission at no extra cost to you. It does not change which products we list or what the data says.

For PFOA

Under-sink reverse osmosis system

under-sink or countertop, about $300

Look for NSF/ANSI 58 certification listing the contaminant you need removed.

For PFOA

Whole-house PFAS carbon system

whole-house, at the point of entry, about $3,000

Granular activated carbon certified to NSF/ANSI 53 for PFOA and PFOS; replace media on schedule.

For PFOA

Aquasana SmartFlow reverse osmosis

under-sink or countertop, about $225

Certified to NSF/ANSI 58 and 53 to reduce arsenic (96%, pentavalent), fluoride (90%), lead (99%), nitrate, nitrite and PFOA/PFOS at the kitchen tap, with a remineralizer.

For PFOS

Aquasana Claryum 3-Stage under-sink filter

under-sink or countertop, about $175

Certified to NSF/ANSI 53 to reduce 99% of lead and 99.7% of PFOA and PFOS at the tap. Not a fix for arsenic, nitrate or bacteria.

For PFOS

Aquasana HealthShield whole-house filter

whole-house, at the point of entry, about $2,099

Whole-house carbon system the maker certifies to reduce PFAS (PFOA and PFOS) and VOCs at every tap; a UV option adds bacteria protection.

For iron

Iron and manganese oxidizing filter

whole-house, at the point of entry, about $1,800

Air-injection or greensand media; fixes staining at the source.

Free, no obligation

Get on the list for a free in-home water test in Washington County

No water treatment company serves Washington County through Well Water Nerd yet. We are signing licensed companies on county by county: they test at your tap for free, walk you through the numbers, and quote treatment only if something needs fixing. Leave your details and you are first in line. Nothing is shared until a company joins for Washington County, and you get an email naming it first.

Common questions

How deep are wells in Washington County?

The typical domestic well in Washington County is 87 feet deep, based on 1,100 wells reported to the state since 1970. One in ten is deeper than 160 feet. 91% are drilled into bedrock.

Is there arsenic in well water in Washington County?

Arsenic was detected in 5% of 19 public well samples in Washington County, and 0% were above the EPA limit of 10 ug/L. Arsenic has no taste or smell; a lab test is the only way to know your level.

How often should I test a private well in Washington County?

Test for bacteria and nitrate every year. Test once for arsenic, uranium, radon, fluoride, manganese and PFAS, then again every three to five years or after any change in taste, color, or plumbing.

Towns in Washington County

19 towns have fewer than 30 public samples and are included in the Washington County totals above rather than shown separately: Adams township, Aurelius township, Barlow township, Belpre, Dunham township, Fairfield township, Fearing township, Grandview township, Independence township, Lawrence township, Liberty township, Ludlow township, Marietta, Marietta township, Newport township, Palmer township, Salem township, Waterford township, Watertown township.

Counties near Washington County

Closest first. Groundwater does not stop at a line on a map, so the next county over is a fair second opinion.

Want the numbers themselves? Download the Ohio dataset as CSV, every county and town, with the sources named.

Sources

Ohio EPA Washington County residential well PFAS sampling: 662 samples in Washington County. Residential well PFAS results from Ohio EPA's Washington County drinking water investigation (sampling by AECOM), published on the Ohio EPA GIS server. Retrieved September 22, 2026.
USGS Water Quality Portal: 248 samples in Washington County. Data from the Water Quality Portal, a service of USGS, EPA and USDA; groundwater samples collected by USGS and cooperators. Retrieved September 3, 2026.
USGS national arsenic model (Ayotte 2017): estimated share of 598 people on private wells in Washington County above 10 ug/L of arsenic, from geology, well depth and land use. County estimates of domestic well users with arsenic above 10 ug/L from the USGS national logistic regression model (Ayotte, Medalie and Qi, 2017), with private well population from the USGS 2015 county water-use compilation (Dieter and others, 2018). Retrieved September 15, 2026.
Ohio DNR water well logs: 2,154 well records in Washington County, 1,100 domestic. Water well logs filed with the Ohio Department of Natural Resources Division of Water Resources since 1948. Only aggregates are shown; owner names and addresses are never stored. Retrieved September 17, 2026.
Ohio EPA regulated sites: 365 regulated sites located in Washington County. Remediation sites, leaking underground storage tank releases (BUSTR) and landfills from the Ohio Environmental Protection Agency and the Division of State Fire Marshal. Retrieved September 17, 2026.

Non-detects count as samples and are treated as zero when computing medians. Exactly at the limit counts as not above it. A sample belongs to the town containing the well's reported coordinates.