Well water in Guernsey County, Ohio
In Guernsey County, sodium was detected in 100% of 36 tested well samples from USGS Water Quality Portal.
The strongest signal is arsenic: 30% of 10 local samples were above the limit, too few samples to carry the headline but first on the test list below.
236 test results across 9 contaminants from at least 33 wells, 1976 to 2014; sodium has the most at 36. Data refreshed September 15, 2026.
Compiled by Nick at Well Water Nerd from public records. How these pages are built
An estimated 9,068 people in Guernsey County get their drinking water from a private well, per USGS 2015 county water use. That is about 23% of residents.
Separately, the USGS national arsenic model estimates that 1% of the 9,068 people on private wells in Guernsey County draw water above 10 ug/L (the model's range is <1% to 1%), from geology and well depth rather than local tests.
What individual samples found
Each row summarizes every public sample for that contaminant inside Guernsey 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 |
|---|---|---|---|---|---|---|
| Arsenic 1976 to 2014 | 10 | 90% | 3 | 90.3 | 10 ug/L EPA limit | |
| Fluoride 1976 to 2014 | 28 | 96% | 0.35 | 4.7 | 4 mg/L EPA limit | |
| Nitrate 1976 to 1983 | 29 | 45% | 0 | 0.62 | 10 mg/L EPA limit | |
| Lead 1977 to 2014 | 13 | 85% | 0 | 0 | 15 ug/L EPA limit | |
| Copper 1976 to 2014 | 12 | 50% | 0 | 0.06 | 1.3 mg/L EPA limit | |
| Sodium 1976 to 2014 | no limit | 36 | 100% | 110 | 64,000 | 20 mg/L health guideline |
| Manganese 1976 to 2014 | no limit | 36 | 97% | 150 | 62,000 | 300 ug/L health guideline |
| Chloride 1976 to 2014 | no limit | 36 | 100% | 33 | 240,000 | 250 mg/L nuisance level |
| Iron 1976 to 2014 | no limit | 36 | 100% | 1,650 | 520,000 | 300 ug/L nuisance level |
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 addressWhat this means
The contaminants most often above their limit here are arsenic (30% of 10 samples) and fluoride (4% of 28 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.
Manganese, Chloride, and Iron are widespread in local groundwater. They are mainly a staining and taste problem, but high manganese also carries a health advisory for infants.
What to test for in Guernsey County
- 1Arsenic30% of 10 local samples were above the limit.
- 2Fluoride4% of 28 local samples were above the limit.
- 3Coliform bacteriaRecommended for every private well, every year.
- 4NitrateRecommended for every private well, especially near farms or septic systems.
- 5ChlorideDetected in 100% of local samples.
- 6IronDetected in 100% of local samples.
- 7ManganeseDetected in 97% of local samples.
- 8Volatile organic compounds (VOCs)230 leaking underground storage tank sites on record locally.
- 9Metals panel7 hazardous waste sites on record locally.
Test your Guernsey County well for arsenic, fluoride 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 $209Already 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 Guernsey County numbers, $29. Every line explained, ranked by what matters, with the fix for each.
Wells in Guernsey County
1,788 domestic wells in Guernsey County are on record with the state since 1970. 95% are drilled into bedrock, and the typical well is 110 feet deep (one in ten goes past 186 feet).
In a typical Guernsey County well, bedrock starts about 12 feet down, the median yield is 3 gallons per minute, 38% 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.
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 Guernsey 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 Guernsey County
Ohio EPA records 230 leaking underground storage tank sites and 7 hazardous waste sites in Guernsey County, among 247 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.
- 230
- leaking underground storage tank sitesGasoline and heating oil that leaked from tanks move through groundwater as benzene, MTBE and other volatile organic compounds.
- 7
- hazardous waste sitesSolvents, degreasers and metals from industrial sites can travel far in fractured bedrock.
- 6
- lined landfills and transfer facilities
- 4
- other remediation projects
Treatment that fits the local profile
Arsenic
Point-of-use reverse osmosis; Adsorptive media (iron-based) whole-house; Anion exchange
Fluoride
Point-of-use reverse osmosis; Activated alumina; Distillation
Chloride
Point-of-use reverse osmosis; Distillation
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 arsenic
Under-sink reverse osmosis system
under-sink or countertop, about $300
Look for NSF/ANSI 58 certification listing the contaminant you need removed.
For arsenic
Whole-house arsenic and uranium filter
whole-house, at the point of entry, about $2,500
Adsorptive iron-based media; sized to your well yield.
For arsenic
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 manganese
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
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Common questions
How deep are wells in Guernsey County?
The typical domestic well in Guernsey County is 110 feet deep, based on 1,788 wells reported to the state since 1970. One in ten is deeper than 186 feet. 95% are drilled into bedrock.
Is there arsenic in well water in Guernsey County?
Arsenic was detected in 90% of 10 public well samples in Guernsey County, and 30% 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 Guernsey 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 Guernsey County
19 towns have fewer than 30 public samples and are included in the Guernsey County totals above rather than shown separately: Adams township, Cambridge township, Center township, Jackson township, Jefferson township, Knox township, Liberty township, Londonderry township, Madison township, Millwood township, Monroe township, Oxford township, Richland township, Spencer township, Valley township, Washington township, Westland township, Wheeling township, Wills township.
Counties near Guernsey 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
- USGS Water Quality Portal: 236 samples in Guernsey 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 9,068 people on private wells in Guernsey 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: 3,469 well records in Guernsey County, 1,788 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: 247 regulated sites located in Guernsey 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.