Manganese and nitrate are widespread in New London County wells.
2 widespread, 2 rare out of 4 health checks.
From 40 wells tested in New London County since 2000; your own well needs its own test. How to read this
Not charted, because fewer than 10 wells were tested: uranium (4), radon (2), lead (4).
Rare: under 5%Worth checking: 5 to 15%Widespread: 15%+
Lab results: Water Quality Portal (USGS and EPA)
Who drinks from a well here
1 in 4 people 61,168 people
Nobody else tests these wells. Only you do.
People on wells: EPA researchers' 2020 estimate
Radon risk (a gas from rock)
Likely here. Test your home's air first.
Radon zones: EPA map
Here's how New London County compares with Connecticut and the counties around it.
Each result puts New London County next to the 7 counties that border it, on the chart's 0 to 50% scale.
These 2 are widespread in New London County wells.
Manganese8 of 26 wells over
Too few tested to show: Kent, RI, Middlesex, Tolland, Washington, RI, Windham.
Nitrate7 of 27 wells over
Too few tested to show: Kent, RI, Middlesex, Windham.
These 2 are rare in New London County.
Arsenic0 of 18 wells over
Too few tested to show: Kent, RI, Middlesex, Tolland, Washington, RI.
Fluoride0 of 25 wells over
Too few tested to show: Kent, RI, Middlesex, Tolland, Washington, RI, Windham.
Too few New London County wells were tested for these 3.
Uranium4 wells tested
Radon in water2 wells tested
Lead4 wells tested
Coliform bacteria turned up in 1 of 2 tested New London County wells, so test for it every year.
Coliform bacteria1 of 2 wells had it
E. coli0 of 2 wells had it
E. coli means human or animal waste is getting in, so if a test of your New London County well finds it, boil drinking water until the well is fixed.
Iron reached staining levels in 8 of 39 tested wells, and it isn't a health risk.
Iron stains8 of 39 wells had it
Too few tested to show: Kent, RI, Middlesex, Tolland, Washington, RI.
New London County has 40 tested wells, and the busiest decade for testing was the 2000s.
None of the 40 wells has a test from 2020 or later, so a fresh test of your own well tells you more than any of these.
Most New London County wells in these records were tested for research or because someone suspected a problem, which can push the shares above what a typical home well would show (how we read the numbers).
One mail-in lab test covers the 4 things to check in New London County.
- Bacteria
- Nitrate
- Manganese
- Arsenic
What Connecticut offers well owners
- Free testingWe didn't find a free program for all of Connecticut. Connecticut's private well page
- Certified labsConnecticut's list of certified labs
- Well recordsWe didn't find an online search.
- New wellsUnder Section 19a-37 of the Connecticut General Statutes, water testing is required for all new private wells, but testing at home sale is not required by law.
Here's what we know about radon and PFAS in New London County.
New London County is in the EPA's highest radon zone. Radon from well water adds to the radon in your indoor air, so test your air first, and your water too if the air is high. Radon guide
Between 2023 and 2025 the EPA had 8 town water systems in New London County test for PFAS. 3 of them had at least one test above 4 ng/L, the new EPA limit for PFOA and PFOS. The highest single result was 16 ng/L of PFOS. No well in New London County has public PFAS results, so the town systems are the best clue to what's in the groundwater nearby. PFAS guide
Radon zones: EPA Map of Radon Zones. PFAS: EPA tests of town water systems, 2023 to 2025
Questions people ask about well water in New London County
Is well water in New London County safe to drink?
8 of 26 wells tested in New London County had manganese over the limit, about 3 in 10. Across Connecticut it's about 2 in 10. So test your own well for manganese before you count on it.
Where can I get my well tested in New London County?
Use a lab Connecticut has certified for drinking water. Connecticut's list is linked above, in the box about testing. Ask for bacteria, nitrate, manganese and arsenic, the tests that matter most in New London County.
How does New London County compare with the counties around it?
For manganese, the share of tested wells over the limit: New London County, at 31%, had a higher share than all 2 neighboring counties with data. Groundwater doesn't stop at county lines, so Hartford's 13% is worth knowing about if you live near it.
How often should I test my well in New London County?
In New London County, 1 of 2 tested wells had coliform bacteria, so the CDC's advice matters here: test for bacteria and nitrate every year, and right away after a flood, a repair, or any change in taste or smell.
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Where the New London County numbers come from
- People on wells: 61,168 in New London County, from EPA estimates built on the 2020 Census (Murray et al.).
- Lab tests: 517 well water samples from 40 wells in the Water Quality Portal, run by the USGS and EPA, 2000 to 2017.
- Neighboring counties: the 7 counties that share a border with New London County, from the Census Bureau's county adjacency file.
- PFAS: EPA tests of 8 town water systems in New London County under the Fifth Unregulated Contaminant Monitoring Rule, 2023 to 2025.
- Radon: New London County is zone 1 on the EPA Map of Radon Zones.
- State programs and links: Department of Public Health, checked November 1, 2026.