Well water in Smithtown, New York

In Smithtown, 2% of 588 tested well samples exceeded the EPA limit for copper (1.3 mg/L), based on public data from USGS Water Quality Portal.

4,327 test results across 14 contaminants from at least 73 wells, 1932 to 2022; iron has the most at 783. Data refreshed September 3, 2026.

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

What individual samples found

Each row summarizes every public sample for that contaminant inside Smithtown. 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
Copper 1971 to 2016	2%	588	68%	0.03	8	1.3 mg/L EPA limit
Fluoride 1966 to 2022	<1%	275	13%	0	48	4 mg/L EPA limit
Lead 1971 to 2016	0%	212	9%	0	0.43	15 ug/L EPA limit
Arsenic 1971 to 2016	0%	103	3%	0	1	10 ug/L EPA limit
Nitrate 1973 to 2021	0%	30	93%	1.06	6.8	10 mg/L EPA limit
Iron 1932 to 2022	no limit	783	42%	0	51,000	300 ug/L nuisance level
Chloride 1932 to 2022	no limit	780	100%	5.5	1,000	250 mg/L nuisance level
Manganese 1966 to 2022	no limit	778	37%	0	29,000	300 ug/L health guideline
Sodium 1966 to 2022	no limit	760	100%	4.85	600	20 mg/L health guideline

Sampled fewer than 10 times, too few to summarize: PFOS (5), PFOA (5), Radium (226 + 228) (4), Uranium (2), Radon (2).

Closer than the town

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 copper (2% of 588 samples) and fluoride (<1% of 275 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 Smithtown

1
Copper
2% of 588 local samples were above the limit.
2
Fluoride
<1% of 275 local samples were above the limit.
3
Coliform bacteria
Recommended for every private well, every year.
4
Radon
Median local reading is 166 pCi/L.
5
Nitrate
Recommended for every private well, especially near farms or septic systems.
6
PFOS
Above the limit in 5 of 5 local samples; too few to quote a rate.
7
PFOA
Above the limit in 5 of 5 local samples; too few to quote a rate.
8
Volatile organic compounds (VOCs)
27 hazardous waste sites on record locally.
9
Metals panel
27 hazardous waste sites on record locally.

Test your Smithtown well for copper, 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 $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 Smithtown numbers, $29. Every line explained, ranked by what matters, with the fix for each.

Wells in Smithtown

85 domestic wells in Smithtown are on record with the state. the typical well is 90 feet deep (one in ten goes past 189 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 Smithtown

Northern Atlantic Coastal Plain aquifer system

Semiconsolidated sand. Coastal plain sands like these give steady yields at moderate depth. Salt water and sodium are the usual issues near the coast, and nitrate where the water table is shallow; arsenic and radon from bedrock are less common.

Classification from the USGS Principal Aquifers of the United States (national map, 2003 edition, GIS release 2015), read at the town 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 Smithtown

NYSDEC remediation sites records 27 hazardous waste sites in Smithtown, among 32 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.

27: hazardous waste sitesSolvents, degreasers and metals from industrial sites can travel far in fractured bedrock.
5: other remediation projects

Treatment that fits the local profile

Copper

Neutralizing filter to raise pH; Point-of-use reverse osmosis

Fluoride

Point-of-use reverse osmosis; Activated alumina; 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

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For copper

Under-sink reverse osmosis system

under-sink or countertop, about $300

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

For copper

Acid neutralizing filter

whole-house, at the point of entry, about $1,200

Raises pH so plumbing stops leaching lead and copper.

For fluoride

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 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 Smithtown

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

Common questions

How deep are wells in Smithtown?

The typical domestic well in Smithtown is 90 feet deep, based on 85 wells reported to the state. One in ten is deeper than 189 feet.

Is there arsenic in well water in Smithtown?

Arsenic was detected in 3% of 103 public well samples in Smithtown, 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 Smithtown?

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 near Smithtown

Closest first. Groundwater does not stop at a line on a map, so the next town 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: 4,327 samples in Smithtown. Data from the Water Quality Portal, a service of USGS, EPA and USDA; groundwater samples collected by USGS and cooperators. Retrieved September 3, 2026.
NYSDEC water well completion reports: 241 well records in Smithtown, 85 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: 32 regulated sites located in Smithtown. 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.