Well water in Southeastern Connecticut Planning Region, Connecticut
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Testing strongly recommended
tested well samples in Southeastern Connecticut Planning Region exceeded the EPA limit for nitrate (10 mg/L), based on public data from USGS Water Quality Portal and Connecticut DPH and USGS arsenic and uranium survey.
2,551 test results across 13 contaminants from at least 244 wells, 1954 to 2025; nitrate has the most at 1,024. 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 Southeastern Connecticut Planning Region. 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 1954 to 2025 | 1,024 | 99% | 4 | 113 | 10 mg/L EPA limit | |
| Arsenic 1972 to 2017 | 66 | 27% | 0 | 160 | 10 ug/L EPA limit | |
| Fluoride 1954 to 2025 | 170 | 56% | 0 | 9.1 | 4 mg/L EPA limit | |
| Uranium 1988 to 2017 | 44 | 27% | 0 | 17 | 30 ug/L EPA limit | |
| Copper 1954 to 2017 | 21 | 76% | 0 | 0.25 | 1.3 mg/L EPA limit | |
| Lead 1972 to 2017 | 19 | 58% | 0 | 0.863 | 15 ug/L EPA limit | |
| Radium (226 + 228) 1988 to 2017 | 11 | 27% | 0 | 1 | 5 pCi/L EPA limit | |
| Iron 1954 to 2025 | no limit | 358 | 83% | 50 | 31,000 | 300 ug/L nuisance level |
| Manganese 1954 to 2025 | no limit | 324 | 100% | 20 | 9,280 | 300 ug/L health guideline |
| Chloride 1954 to 2025 | no limit | 276 | 100% | 19 | 3,620 | 250 mg/L nuisance level |
| Sodium 1954 to 2025 | no limit | 229 | 100% | 14 | 1,590 | 20 mg/L health guideline |
Sampled fewer than 10 times, too few to summarize: E. coli (2), Radon (7).
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 | 21%150 samples | 33%446 samples | 25%288 samples | 17%140 samples |
| Fluoride | 1%73 samples | 0%20 samples | n/a | 0%70 samples |
| Arsenic | 0%18 samples | 0%14 samples | 6%34 samples | n/a |
| Uranium | 0%19 samples | n/a | 0%24 samples | n/a |
Nitrate above the limit in Southeastern Connecticut Planning Region fell from 25% of 288 samples in the 2010s to 17% of 140 in the 2020s.
Fluoride has 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 nitrate (27% of 1,024 samples), arsenic (3% of 66 samples), and fluoride (<1% of 170 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.
The median radon reading (3,200 pCi/L) is above the 2,000 pCi/L level at which treatment is recommended. Radon in water raises indoor air radon when it is used for showers and laundry.
What to test for in Southeastern Connecticut Planning Region
- 1Nitrate27% of 1,024 local samples were above the limit.
- 2Arsenic3% of 66 local samples were above the limit.
- 3Fluoride<1% of 170 local samples were above the limit.
- 4Coliform bacteriaRecommended for every private well, every year.
- 5RadonMedian local reading is 3,200 pCi/L.
- 6ManganeseDetected in 100% of local samples.
- 7ChlorideDetected in 100% of local samples.
- 8Volatile organic compounds (VOCs)724 leaking underground storage tank sites on record locally.
- 9Metals panel6 hazardous waste sites on record locally.
Test your Southeastern Connecticut Planning Region well for nitrate, arsenic 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 Connecticut: certified labs, state programs and prices.
Already have results back? Get your lab report read against the Southeastern Connecticut Planning Region numbers, $29. Every line explained, ranked by what matters, with the fix for each.
Wells in Southeastern Connecticut Planning Region
703 domestic wells in Southeastern Connecticut Planning Region are on record with the state since 1925. the typical well is 340 feet deep (one in ten goes past 600 feet).
In a typical Southeastern Connecticut Planning Region well, the median yield is 8 gallons per minute, 17% 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 Southeastern Connecticut Planning Region
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 planning region 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 Southeastern Connecticut Planning Region
CT DEEP contaminated sites and landfills records 724 leaking underground storage tank sites, 6 hazardous waste sites, and 47 reported spills and releases in Southeastern Connecticut Planning Region, among 1,424 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.
- 724
- leaking underground storage tank sitesGasoline and heating oil that leaked from tanks move through groundwater as benzene, MTBE and other volatile organic compounds.
- 6
- hazardous waste sitesSolvents, degreasers and metals from industrial sites can travel far in fractured bedrock.
- 47
- reported spills and releasesMost spills are fuel; a few are solvents or chemicals that reach the water table.
- 39
- lined landfills and transfer facilities
- 608
- other remediation projects
Treatment that fits the local profile
Nitrate
Point-of-use reverse osmosis; Anion exchange; Distillation
Arsenic
Point-of-use reverse osmosis; Adsorptive media (iron-based) whole-house; Anion exchange
Fluoride
Point-of-use reverse osmosis; Activated alumina; Distillation
Radon
Aeration (bubble-up or diffused) whole-house; Granular activated carbon whole-house (lower levels only)
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 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 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 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.
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Common questions
How deep are wells in Southeastern Connecticut Planning Region?
The typical domestic well in Southeastern Connecticut Planning Region is 340 feet deep, based on 703 wells reported to the state since 1925. One in ten is deeper than 600 feet.
Is there arsenic in well water in Southeastern Connecticut Planning Region?
Arsenic was detected in 27% of 66 public well samples in Southeastern Connecticut Planning Region, 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 often should I test a private well in Southeastern Connecticut Planning Region?
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 Southeastern Connecticut Planning Region
15 towns have fewer than 30 public samples and are included in the Southeastern Connecticut Planning Region totals above rather than shown separately: Bozrah, Colchester, Franklin, Groton, Lebanon, Ledyard, Lisbon, Montville, New London, North Stonington, Norwich, Preston, Salem, Sprague, Windham.
Planning regions near Southeastern Connecticut Planning Region
Closest first. Groundwater does not stop at a line on a map, so the next planning region 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: 2,499 samples in Southeastern Connecticut Planning Region. 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 DPH and USGS arsenic and uranium survey: 52 samples in Southeastern Connecticut Planning Region. Arsenic and uranium in 674 private bedrock wells sampled by the Connecticut Department of Public Health with the U.S. Geological Survey, 2013 to 2015. Retrieved .
- Connecticut well completion reports: 1,087 well records in Southeastern Connecticut Planning Region, 703 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: 1,424 regulated sites located in Southeastern Connecticut Planning Region. 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.