Well water in Stonington, Connecticut
In Stonington, iron was detected in 97% of 31 tested well samples from USGS Water Quality Portal.
The strongest signal is nitrate: 14% of 22 local samples were above the limit, too few samples to carry the headline but first on the test list below.
175 test results across 10 contaminants from at least 25 wells, 1963 to 1989; iron has the most at 31. 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 Stonington. 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 1965 to 1989 | 22 | 100% | 0.796 | 25 | 10 mg/L EPA limit | |
| Fluoride 1965 to 1982 | 13 | 54% | 0.1 | 0.3 | 4 mg/L EPA limit | |
| Copper 1982 | 12 | 67% | 0 | 0.02 | 1.3 mg/L EPA limit | |
| Lead 1982 | 12 | 58% | 0 | 0 | 15 ug/L EPA limit | |
| Arsenic 1982 | 12 | 50% | 0.5 | 1 | 10 ug/L EPA limit | |
| Iron 1963 to 1982 | no limit | 31 | 97% | 70 | 8,200 | 300 ug/L nuisance level |
| Manganese 1965 to 1982 | no limit | 30 | 100% | 20 | 1,800 | 300 ug/L health guideline |
| Chloride 1965 to 1989 | no limit | 29 | 100% | 8.4 | 324 | 250 mg/L nuisance level |
| Sodium 1965 to 1982 | no limit | 13 | 100% | 6.1 | 71 | 20 mg/L health guideline |
Sampled fewer than 10 times, too few to summarize: Uranium (1).
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 (14% of 22 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.
Iron, Manganese, and Chloride 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 Stonington
- 1Nitrate14% of 22 local samples were above the limit.
- 2Coliform bacteriaRecommended for every private well, every year.
- 3ManganeseDetected in 100% of local samples.
- 4ChlorideDetected in 100% of local samples.
- 5IronDetected in 97% of local samples.
- 6CopperDetected in 67% of local samples.
- 7FluorideDetected in 54% of local samples.
- 8Volatile organic compounds (VOCs)76 leaking underground storage tank sites on record locally.
Test your Stonington well for nitrate, coliform bacteria and manganese
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 Connecticut: certified labs, state programs and prices.
Already have results back? Get your lab report read against the Stonington numbers, $29. Every line explained, ranked by what matters, with the fix for each.
Wells in Stonington
44 domestic wells in Stonington are on record with the state since 2021. the typical well is 310 feet deep (one in ten goes past 600 feet).
In a typical Stonington well, the median yield is 9 gallons per minute, 14% of wells yield under 3 gallons per minute and usually need a storage tank.
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 Connecticut well completion reports and choose Water Well.
- The report lists depth, depth to rock, casing, static water level and yield.
Only reports filed online since January 2021 are here; older paper reports are held by the Department of Consumer Protection.
The rock under Stonington
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 town centroid. A single well can sit in a different unit, especially near a boundary.
Official help in Connecticut
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, CT DPH
- Environmental Laboratory Certification, CT DPH
Contamination sources on record in Stonington
CT DEEP contaminated sites and landfills records 76 leaking underground storage tank sites and 2 reported spills and releases in Stonington, among 133 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.
- 76
- leaking underground storage tank sitesGasoline and heating oil that leaked from tanks move through groundwater as benzene, MTBE and other volatile organic compounds.
- 2
- reported spills and releasesMost spills are fuel; a few are solvents or chemicals that reach the water table.
- 3
- lined landfills and transfer facilities
- 52
- other remediation projects
Treatment that fits the local profile
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 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 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 Stonington
No water treatment company serves Stonington 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 Stonington, and you get an email naming it first.
Common questions
How deep are wells in Stonington?
The typical domestic well in Stonington is 310 feet deep, based on 44 wells reported to the state since 2021. One in ten is deeper than 600 feet.
Is there arsenic in well water in Stonington?
Arsenic was detected in 50% of 12 public well samples in Stonington, 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 Stonington?
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 Stonington
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 Connecticut dataset as CSV, every county and town, with the sources named.
Sources
- USGS Water Quality Portal: 175 samples in Stonington. Data from the Water Quality Portal, a service of USGS, EPA and USDA; groundwater samples collected by USGS and cooperators. Retrieved September 3, 2026.
- Connecticut well completion reports: 94 well records in Stonington, 44 domestic. Well completion reports filed online with the Connecticut Department of Consumer Protection since January 2021. Only aggregates are shown; owner names and addresses are never stored. Retrieved September 16, 2026.
- CT DEEP contaminated sites and landfills: 133 regulated sites located in Stonington. Contaminated or potentially contaminated sites and solid waste landfills from the Connecticut Department of Energy and Environmental Protection. 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.