Well water in Southold, New York
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Testing strongly recommended
tested well samples in Southold exceeded the EPA limit for nitrate (10 mg/L), based on public data from USGS Water Quality Portal.
1,198 test results across 15 contaminants from at least 79 wells, 1932 to 2025; chloride has the most at 281. 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 Southold. 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 |
|---|---|---|---|---|---|---|
| Nitrate 1973 to 2024 | 51 | 96% | 6.81 | 23 | 10 mg/L EPA limit | |
| Copper 1971 to 2018 | 70 | 31% | 0 | 1.33 | 1.3 mg/L EPA limit | |
| Fluoride 1971 to 2025 | 70 | 59% | 0.1 | 4.4 | 4 mg/L EPA limit | |
| Arsenic 1971 to 2016 | 27 | 22% | 0 | 10 | 10 ug/L EPA limit | |
| Lead 1971 to 2016 | 26 | 69% | 0 | 7 | 15 ug/L EPA limit | |
| Chloride 1932 to 2025 | no limit | 281 | 100% | 29 | 18,000 | 250 mg/L nuisance level |
| Iron 1932 to 2025 | no limit | 227 | 94% | 250 | 19,000 | 300 ug/L nuisance level |
| Manganese 1971 to 2025 | no limit | 224 | 71% | 30 | 9,000 | 300 ug/L health guideline |
| Sodium 1971 to 2025 | no limit | 215 | 100% | 15 | 8,000 | 20 mg/L health guideline |
Sampled fewer than 10 times, too few to summarize: PFOA (1), Radium (226 + 228) (2), Uranium (1), PFOS (1), E. coli (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 |
|---|---|---|---|---|
| Nitrate | 31%29 samples | n/a | n/a | 0%13 samples |
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 addressWhat this means
The contaminants most often above their limit here are nitrate (25% of 51 samples), copper (1% of 70 samples), and fluoride (1% of 70 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, Iron, and Manganese 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 Southold
- 1Nitrate25% of 51 local samples were above the limit.
- 2Copper1% of 70 local samples were above the limit.
- 3Fluoride1% of 70 local samples were above the limit.
- 4Coliform bacteriaRecommended for every private well, every year.
- 5RadonMedian local reading is 72 pCi/L.
- 6PFOAAbove the limit in 1 of 1 local samples; too few to quote a rate.
- 7ChlorideDetected in 100% of local samples.
- 8Volatile organic compounds (VOCs)8 hazardous waste sites on record locally.
- 9Metals panel8 hazardous waste sites on record locally.
Test your Southold well for nitrate, copper and fluoride
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 Southold numbers, $29. Every line explained, ranked by what matters, with the fix for each.
Wells in Southold
1,589 domestic wells in Southold are on record with the state. the typical well is 56 feet deep (one in ten goes past 90 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.
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 Southold
NYSDEC remediation sites records 8 hazardous waste sites in Southold, among 9 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.
- 8
- 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
Nitrate
Point-of-use reverse osmosis; Anion exchange; Distillation
Copper
Neutralizing filter to raise pH; Point-of-use reverse osmosis
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
Systems we would look at first
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For nitrate
Under-sink reverse osmosis system
under-sink or countertop, about $300
Look for NSF/ANSI 58 certification listing the contaminant you need removed.
For nitrate
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 copper
Acid neutralizing filter
whole-house, at the point of entry, about $1,200
Raises pH so plumbing stops leaching lead and copper.
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 Southold
No water treatment company serves Southold 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 Southold, and you get an email naming it first.
Common questions
How deep are wells in Southold?
The typical domestic well in Southold is 56 feet deep, based on 1,589 wells reported to the state. One in ten is deeper than 90 feet.
Is there arsenic in well water in Southold?
Arsenic was detected in 22% of 27 public well samples in Southold, 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 Southold?
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 Southold
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: 1,198 samples in Southold. 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: 2,303 well records in Southold, 1,589 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: 9 regulated sites located in Southold. 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.