Well water in Oswego County, New York
In Oswego County, 3% of 31 tested well samples exceeded the EPA limit for arsenic (10 ug/L), based on public data from USGS Water Quality Portal.
584 test results across 11 contaminants from at least 63 wells, 1964 to 2022; fluoride has the most at 89. Data refreshed September 15, 2026.
Compiled by Nick at Well Water Nerd from public records. How these pages are built
An estimated 37,821 people in Oswego County get their drinking water from a private well, per USGS 2015 county water use. That is about 31% of residents.
Separately, the USGS national arsenic model estimates that 1% of the 37,821 people on private wells in Oswego 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 Oswego 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 1985 to 2022 | 31 | 61% | 0.3 | 17.8 | 10 ug/L EPA limit | |
| Nitrate 1985 to 2022 | 82 | 66% | 0.222 | 22 | 10 mg/L EPA limit | |
| Fluoride 1964 to 2022 | 89 | 73% | 0.1 | 0.92 | 4 mg/L EPA limit | |
| Copper 1985 to 2022 | 31 | 77% | 0.002 | 0.016 | 1.3 mg/L EPA limit | |
| Lead 1985 to 2022 | 31 | 65% | 0.1 | 3.5 | 15 ug/L EPA limit | |
| Uranium 2007 to 2022 | 26 | 77% | 0.116 | 4.51 | 30 ug/L EPA limit | |
| E. coli 2007 to 2022 | 10 | 0% | 0 | 0 | 0 MPN/100mL EPA limit | |
| Sodium 1964 to 2022 | no limit | 89 | 100% | 5.4 | 340 | 20 mg/L health guideline |
| Manganese 1964 to 2022 | no limit | 89 | 90% | 14 | 1,600 | 300 ug/L health guideline |
| Iron 1964 to 2022 | no limit | 89 | 88% | 18.1 | 1,040 | 300 ug/L nuisance level |
| Radon 2007 to 2022 | no limit | 17 | 100% | 580 | 2,400 | 2,000 pCi/L health guideline |
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 |
|---|---|---|---|---|
| Fluoride | 0%63 samples | n/a | 0%20 samples | n/a |
| Nitrate | 2%56 samples | n/a | 0%20 samples | n/a |
Fluoride, nitrate have held within a few points between the two most recent periods with enough samples.
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 (3% of 31 samples) and nitrate (1% of 82 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 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 Oswego County
- 1Arsenic3% of 31 local samples were above the limit.
- 2Nitrate1% of 82 local samples were above the limit.
- 3Coliform bacteriaRecommended for every private well, every year.
- 4RadonMedian local reading is 580 pCi/L.
- 5ManganeseDetected in 90% of local samples.
- 6IronDetected in 88% of local samples.
- 7CopperDetected in 77% of local samples.
- 8Volatile organic compounds (VOCs)47 hazardous waste sites on record locally.
- 9Metals panel47 hazardous waste sites on record locally.
Test your Oswego County well for arsenic, nitrate 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 New York: certified labs, state programs and prices.
Already have results back? Get your lab report read against the Oswego County numbers, $29. Every line explained, ranked by what matters, with the fix for each.
Wells in Oswego County
2,062 domestic wells in Oswego County are on record with the state. the typical well is 75 feet deep (one in ten goes past 138 feet).
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 NYSDEC water well completion reports and choose Water Well.
- The report lists depth, depth to bedrock, cased depth, yield and the driller.
Drillers have filed reports with the state since April 2000; a well drilled before then usually has no record.
The rock under Oswego County
New York sandstone 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 New York
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 Wells, NYSDOH
- Environmental Laboratory Approval Program, NYSDOH
Contamination sources on record in Oswego County
NYSDEC remediation sites records 47 hazardous waste sites in Oswego County, among 77 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.
- 47
- hazardous waste sitesSolvents, degreasers and metals from industrial sites can travel far in fractured bedrock.
- 30
- other remediation projects
Treatment that fits the local profile
Arsenic
Point-of-use reverse osmosis; Adsorptive media (iron-based) whole-house; Anion exchange
Nitrate
Point-of-use reverse osmosis; Anion exchange; Distillation
Manganese
Oxidizing filter (greensand, birm) whole-house; Water softener (low levels); Point-of-use reverse osmosis
Iron
Oxidizing filter whole-house; Water softener (low levels); Aeration plus filtration
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 Oswego County?
The typical domestic well in Oswego County is 75 feet deep, based on 2,062 wells reported to the state. One in ten is deeper than 138 feet.
Is there arsenic in well water in Oswego County?
Arsenic was detected in 61% of 31 public well samples in Oswego County, and 3% 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 high is radon in well water in Oswego County?
The median radon level across 17 public samples in Oswego County was 580 pCi/L, with a high of 2,400 pCi/L. New Hampshire recommends treatment above 2,000 pCi/L.
How often should I test a private well in Oswego 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 Oswego County
23 towns have fewer than 30 public samples and are included in the Oswego County totals above rather than shown separately: Albion, Amboy, Boylston, Constantia, Fulton, Granby, Hannibal, Hastings, Mexico, Minetto, New Haven, Orwell, Oswego, Oswego, Palermo, Parish, Redfield, Richland, Sandy Creek, Scriba, Volney, West Monroe, Williamstown.
Counties near Oswego 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 New York dataset as CSV, every county and town, with the sources named.
Sources
- USGS Water Quality Portal: 584 samples in Oswego 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 37,821 people on private wells in Oswego 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.
- NYSDEC water well completion reports: 2,082 well records in Oswego County, 2,062 domestic. Water well completion reports filed with the New York State Department of Environmental Conservation Water Well Contractor Program since 2000. Only aggregates are shown; owner names and addresses are never stored. Retrieved September 16, 2026.
- NYSDEC remediation sites: 77 regulated sites located in Oswego County. State Superfund, brownfield, voluntary cleanup, RCRA and spill remediation sites from the New York State Department of Environmental Conservation Environmental Remediation Sites database. Retrieved September 16, 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.