Well water in Delaware County, New York

In Delaware County, none of 47 tested well samples exceeded the EPA limit for fluoride, based on public data from USGS Water Quality Portal.

The strongest signal is E. coli: 6% of 17 local samples were above the limit, too few samples to carry the headline but first on the test list below.

324 test results across 9 contaminants from at least 47 wells, 1949 to 2020; fluoride has the most at 47. Data refreshed September 15, 2026.

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

An estimated 14,891 people in Delaware County get their drinking water from a private well, per USGS 2015 county water use. That is about 32% of residents.

Separately, the USGS national arsenic model estimates that 3% of the 14,891 people on private wells in Delaware County draw water above 10 ug/L (the model's range is 2% to 4%), from geology and well depth rather than local tests.

What individual samples found

Each row summarizes every public sample for that contaminant inside Delaware 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
E. coli 2001 to 2020	6%	17	6%	0	6	0 MPN/100mL EPA limit
Fluoride 1949 to 2020	0%	47	85%	0.07	0.5	4 mg/L EPA limit
Lead 1971 to 2020	0%	37	78%	0.21	6.97	15 ug/L EPA limit
Arsenic 1971 to 2020	0%	37	81%	0.2	8	10 ug/L EPA limit
Copper 1971 to 2020	0%	37	81%	0.01	0.62	1.3 mg/L EPA limit
Uranium 2001 to 2020	0%	29	66%	0.02	4.25	30 ug/L EPA limit
Manganese 1949 to 2020	no limit	46	89%	12.3	570	300 ug/L health guideline
Sodium 1957 to 2020	no limit	45	100%	9.39	136	20 mg/L health guideline
Radon 2001 to 2020	no limit	29	100%	1,120	1,980	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%18 samples	0%14 samples	0%10 samples	n/a
Lead	n/a	0%14 samples	0%10 samples	n/a
Arsenic	n/a	0%14 samples	0%10 samples	n/a
Copper	n/a	0%14 samples	0%10 samples	n/a
Uranium	n/a	0%14 samples	0%10 samples	n/a

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 e. coli (6% of 17 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 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 Delaware County

1
E. coli
6% of 17 local samples were above the limit.
2
Radon
Median local reading is 1,120 pCi/L.
3
Nitrate
Recommended for every private well, especially near farms or septic systems.
4
Manganese
Detected in 89% of local samples.
5
Fluoride
Detected in 85% of local samples.
6
Copper
Detected in 81% of local samples.
7
Volatile organic compounds (VOCs)
17 hazardous waste sites on record locally.
8
Metals panel
17 hazardous waste sites on record locally.

Test your Delaware County well for E. coli, radon and nitrate

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 New York: certified labs, state programs and prices.

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

Wells in Delaware County

2,589 domestic wells in Delaware County are on record with the state. the typical well is 273 feet deep (one in ten goes past 507 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 Delaware County

Not a principal aquifer

The USGS map places this area outside any principal aquifer, which usually means wells here draw from fractured bedrock or thin local deposits rather than a large regional aquifer. Bedrock wells of that kind are where arsenic, radon and uranium turn up, and yields vary from well to well.

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 Delaware County

NYSDEC remediation sites records 17 hazardous waste sites in Delaware County, among 18 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.

17: hazardous waste sitesSolvents, degreasers and metals from industrial sites can travel far in fractured bedrock.
1: other remediation project

Treatment that fits the local profile

E. coli

Shock chlorination and fix the well cap or casing; UV disinfection whole-house; Chlorination system

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 E. coli

UV disinfection system

whole-house, at the point of entry, about $900

Fix the well cap and casing first; UV keeps bacteria from returning.

For E. coli

Aquasana Rhino Well Water with UV

whole-house, at the point of entry, about $2,871

Whole-house system built for wells: sediment pre-filter, KDF and carbon, and a UV lamp rated to kill 99.99% of bacteria and viruses. It does not remove arsenic, nitrate, uranium or radon.

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

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

No water treatment company serves Delaware 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 Delaware County, and you get an email naming it first.

Common questions

How deep are wells in Delaware County?

The typical domestic well in Delaware County is 273 feet deep, based on 2,589 wells reported to the state. One in ten is deeper than 507 feet.

Is there arsenic in well water in Delaware County?

Arsenic was detected in 81% of 37 public well samples in Delaware 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 high is radon in well water in Delaware County?

The median radon level across 29 public samples in Delaware County was 1,120 pCi/L, with a high of 1,980 pCi/L. New Hampshire recommends treatment above 2,000 pCi/L.

How often should I test a private well in Delaware 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 Delaware County

19 towns have fewer than 30 public samples and are included in the Delaware County totals above rather than shown separately: Andes, Bovina, Colchester, Davenport, Delhi, Deposit, Franklin, Hamden, Hancock, Harpersfield, Kortright, Masonville, Meredith, Middletown, Roxbury, Sidney, Stamford, Tompkins, Walton.

Counties near Delaware 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: 324 samples in Delaware 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 14,891 people on private wells in Delaware 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: 2,634 well records in Delaware County, 2,589 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: 18 regulated sites located in Delaware 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.